Scientists build computer from DNA molecules

S cientists at the Weizmann Institute, Israel have built a DNA computer  that is so small that a trillion of them  could fit in a test tube and perform a  billion operations per second with 99.8 per cent accuracy. Instead of using  figures and formulas to solve a  problem, the microscopic computer's  input, output and softwares are made up of DNA molecules, which store and  process encoded information in living  organisms. It is the first programmable  autonomous computing machine in  which the input, output, software and  hardware are all made up of  biomolecules. Scientists see such DNA  computers as future competitors for  their more conventional counterparts  because miniaturization is reaching its  limits and DNA has the potential to be  much faster than conventional  computers.
            The new model could form the  basis of a DNA computer in the near  future that could potentially operate  within human cells and act as a  monitoring device to detect potentially  disease-causing changes and  synthesize drugs to fix them. It could even form the basis of computers for  screening DNA libraries in parallel  without sequencing each molecule.  This would speed up the acquisition of  knowledge about DNA, which can  hold more information in a cubic  centimetre than a trillion CDs. The  double helix molecule that contains  human genes stores data on four  chemical bases – known by the letters A, T, C and  G – giving it massive  memory capability that scientists are  only just beginning to tap into.


Jan- Feb, 2002 Vatis Update:


New family ties to asthma

I n addition  to environment factors, asthma has a strong genetic components,  and several chromosomal regions are  linked with susceptibility to asthma and  allergy. By taking advantage of the  similarities between mouse and human  genomes, Jennifer McIntire and co- workers have identified a new family of  candidate asthma-susceptibility genes.             Asthma is a chronic debilitating  disease that is characterized by airway  hyper reactivity and inflammation.  Allergic asthma is the most common form  of the disease and is thought to result from immune responses to normally harmless inhaled antigens. This leads to the accumulation of effector cells, such as 
mast cells and eosinophils, and the release 
of inflammatory mediators. T-helper type 
2 (TH2) responses underpin the development of allergic responses. In this respect, it is intriguing that a region of  human chromosomes 5 associated with  susceptibility to asthma (5q23-35)  contains many genes that regulate TH2-cell development – including the interleukins  ILA, IL5, IL13, IL9 and IL12p40 – but  none of these has yet been proven to be an 
asthma-suscepatibility gene.
            Allergen – induced airway 
hyperreactivity (AHR) in mice is an 
experimental model of asthma. Cogenic  mice strains were generated in which  AHR-susceptible BALB/c mice carry  small segments of chromosomes from  
resistant DBA/2 mice. The congenic  mouse strains were then screened for  reduced IL-4 production and resistance to  AHR. This approach identified a  susceptibility locus which is homologous  with human 5q33, and has been named  Tapr (T cell and airway phenotype  regulator).
            Fine mapping of the locus shows
Tapr is distinct from the IL4 gene cluster, IL12p40, and other candidate genes found in the syntenic region of human  chromosomes 5. Positional cloning of  Tapr uncovered a new family of three  genes that are named Tim. Tim1, Tim2  and Tim3 are transmembrane proteins with extracellular immunoglobulin-like and  mucin-like domains, and an intracellular  tail with tyrosine phosposphorylation sites.  The human homologue of Tim1 is the  hepatitis A virus receptor (HAVR), which  might explain the inverse relationship between HAV infection and allergic  diseases.
            Sequencing of Tim1 and Tim3 showed major polymorphisms between the  susceptible and resistant mouse strains.  But how might Tim variants influence TH
development? The mechanism  is not  clear, but it seems that Tim expression by  activated T cells early in activation might  be crucial in controlling the polarization of  T cells for TH2-cytokine secretion. 

January 2002, Nature Reviews 
Immunology. Vol. 2


Novel antibiotic found in human sweat  

R esearchers in Germany have discovered an antimicrobial  peptide produced by human sweat  glands. They believe that this  molecule, called dermcidin, could play  an important part in the first line of  defence against pathogenic  microorganisms that affect the skin. Its  activity might help to explain  observations that link frequent washing   with increased susceptibility to skin  infections. Other mammalian  antimicrobial peptides, called  cathelicidins and B-defensins, are  expressed in human keratincytes in  response to inflammatory stimuli or  injury, “but this peptide is the first one  to be expressed constitutively”, says  Garbe. He suggests that the peptide  might account for the scarcity of skin  infections compared with infection in  other organs. Dermicidin was shown to  have antimicrobial activity against  Escherichia coli, Enterococcus  faecalis, Staphylococcus aureus, and  Candida albicans at pH values and salt  concentrations resembling those in  human sweat.  Asked about the possible  application of these findings, Garbe  says: “The obvious thing would be to  synthesise the peptide and use it in  creams… there are illness of the  skin which are directly linked  colonisation by bacteria, such as  Pseudomonas aeruginosa”. He adds  that using  a naturally produced  compound should have the advantage  of not inducing resistance or allergies.  “If we are to produce it by means of  gene technology, we cannot do it in  bacteria because the peptide kills them,  so we are planning to try using plants”,  he concludes.

February 2002, The Lancet Vol. 2

Hand-held device detects fake drugs

A  simple device that is normally  used to examine urine specimens  can also be used to detect counterfeit  drugs, says Michael Green, who  reported his findings at the American  Society of Tropical medicine and  Hygiene’s 50th  Annual Meeting  (Atlanta, USA; Nov 11-15). If  someone takes a drug and it doesn’t  work, you’re suspicious. Or, if you’re  very observant, you’ll see that the labelling  may be slightly different or  the drug doesn’t took quite right.  Mainly, if the price is a lot lower than  the normal price, then that raises our  suspicions and we’d check it out” adds  Green.  But it is not possible to do  detailed investigations of suspect drugs  in less-developed countries that lack  resources and technical expertise. And  so Green and co-workers developed a  simple test using a hand-held  refractometer,  a “low-tech” device  that measures the specific gravity of  urine samples and costs less than  US$100. They realised that by  measuring the specific gravity of  certain dissolved drugs, a drug tester  could  ascertain the amount of active  ingredient in a tablet, and thus detect a  bogus medication. Although the  method cannot identify an unknown  drug,  and may not work for all drugs (excipients,  buffers, and flavouring   could interfere), it “could be used as a  first  line of defense against counterfeit  drugs”. 
            The tester simply takes a  sample of the medication, pulverises it,  dissolves it in alcohol, and filters out any remaining solids. A drop of the  clear solution is placed on the  refractometer, which gives the  refractive index. That index can be  converted to specific gravity and  compared with a standard already  established for that particular drug.

January  2002, The Lancet Vol. 2


Never ceasing wonder

A lready hailed as a wonder drug, the  humble aspirin can also combat  common viruses, reveals research  carried out by Thomas Shenk and his  team at Princeton University in New  Jersey, USA. The researchers have  found that close relatives  of aspirin can  block common viruses known as the  human cytomegaloviruses (CMV),  which are members of the family that  causes cold sores and herpes  infections. CMV, present in one tenth  of the population, can cause hearing  problems in babies born to infected  mothers and kill patients with reduced  immunity, such as those suffering from  AIDS. Shenk and his colleagues have  shown that aspirin-like drugs can stop  CMV from replicating in infected  cells. The drugs do this by blocking  production of cyclooxygenase 2, an  enzyme better known as COX-2. The  enzyme helps in the making of  prostaglandin E2, a chemical that  triggers fever and inflammation. But  prostaglandin E2 can be   commandeered by viruses to help them  multiply. Shenk showed that  fibroblasts (taken from human  foreskins) infected with CMV made 50  times more prostaglandin E2 than  normal. But the cells stopped making  E2 as soon as they were exposed to the  aspirin-like drugs. At   the same time,  virus production by the cells dropped  100-fold.

March 31, 2002 Down To Earth 


Trials on Alzheimer’s vaccine drug suspended      

T rials of a vaccine against  Alzheimer;s disease, which was  being used on 360 people with mild to  moderate disease, have been suspended  after 12 volunteers became seriously  ill. The vaccine, known as AN1792, is  being developed by the Irish based  pharmaceutical company Elan, in  partnership with Wyeth-Ayerst  Laboratories.   

March 2, 2002  BMJ Vol.  324


Minimum standard of care defined for HIV patients with cancer

An international panel convened by WHO has drawn up draft  guidelines for  a minimum standard of  care for patients with the most  common HIV- associated cancers in  Africa. These are Kaposi’s sarcoma,  non-Hodgkin’s lymphoma and  squamous cell carcinoma of the  conjunctiva. Kaposi’s sarcoma and  non-Hodgkin’s lymphoma are  responsive to treatment but they are  not curable. The only realistic public  health approach to them is palliative  care. The guidelines for this include  advice on human resources, infrastructure, clinical management,  quality of life, and anti retroviral  therapy. 

Bulletin of the World Health 
Organization 2002 


New research needed for polio 

WHO has prepared a research agenda to investigate how and  when immunization against polio can be discontinued after polio eradication  is achieved. The WHO Department of  Vaccines and Biologicals is  establishing a steering committee for  this work; its task is to ensure that the  Technical Consultative Group for  Polio Eradication will have the  relevant scientific data on the post- eradication vaccination policy options. These will be submitted to the World  Health Assembly for a decision. The  budget for the research agenda is US$ 1 million a year for the next five years. The following five areas of  research will be covered: Surveillance for vaccine-derived  polioviruses Effectiveness of inactivated polio vaccine in stopping transmission  of polioviruses. How to discontinue oral polio vaccination safely if no alternative  vaccine is used Long-term poliovirus excretors Type of vaccine to use for an  outbreak response in the post immunization era.

World Health Organization 2002  


Some plants can reduce pollution

Plants are magic wands that can do wonders to us. Some of them can  even act as “bioremediators” – they  can either absorb or break down  pollution particles into harmless  components. Research about this is  being conducted in many places. The  Hong Kong Baptist University claims  that trees like Leucaena leucocephala  and Acacia confusa  can be used for  restoring landfills. A study conducted  by Lucknow-based National Botanical  Research Institute (NBRI) shows that  mycorhizal fungi present in plant roots  can absorb copper and zinc. The  institute is even attempting to show in  field conditions that chromium can be  removed from soil using plants such as  Scripus lacustris and Typha latifolia.  Another study carried out by NBRI in  collaboration with the University of  Munchen, Germany, shows that  aquatic  plants like Hydrilla verticillata  and Vallisneria spiralis have enzymes  to detoxify heavy metals like  cadmium, lead and mercury.    However, despite its economic  viability, the technique has failed to  take off. “People are unwilling to grow  bioremediators as they do not give a  cash return,” says Sarita Sinha, a  scientist at NBRI.         


March 15, 2002, Down To Earth


Better surveillance needed for second colorectal cancers

Despite intensive surveillance after  treatment of an initial cancer, the  incidence of second primary colorectal  cancer remains high in patients with a  history of the disease. Green and co-workers analysed  data from 3278 patients with resected  stage II or stage III colorectal cancer  who participated in a multicentre   adjuvant chemotherapy trial that  included surveillance based on current,  but unproven guidelines: colonoscopy  1 year after treatment and every 3-5  years if results are normal.   During 15 245 patient–years of  follow-up, 42 cases of second primary  colorectal cancers developed. The  standardized incidence ratio was 1.6  compared with the Surveillance,  Epidemiology, and End results (SEER)  programme and 6.8 compared with the  National Polyp Study.  Paul Limburg (Mayo Clinic,  Rochester, MN, USA) warns that the  high rate of second cancers reflects “a  failure in patient management”, and  stresses that both physicians and  patients  “need to do a better job of  adhering to existing guidelines” for the  detection of synchronous and second  cancers. Colonoscopy is the preferred  method, he notes, but computed  tomography colonography is an option  if colonoscopy can’t be completed  because of an obstructing tumour.              The researchers note that their   study does not prove that more frequent colonoscopy would have  improved patients’ outcomes, and that  any recommendations for changes in  surveillance strategies must take into  account the complications and cost of  the technique.   


February 23, 2024 The Lancet  
Vol. 359

Cardiovascular risk of diabetes

Two thirds of people with diabetes are unaware that they have an  increased risk of cardiovascular  disease and stroke, according to a poll of 2008 diabetic individuals released on Feb 19 by the American Diabetes Association. Many knew little about steps they could take to decrease their cardiovascular risk, such as taking aspirin, reducing their cholesterol concentrations, and stopping smoking.  

February 23, 2024 The Lancet  
Vol. 359


Vaccine news from the different worlds    


t  seems that vaccine development has never had such a high profile.  With vaccines available against smallpox and anthrax, how exactly  they should be used to combat the  threat of bioterrorism has been a  subject of  debate in the US press. A  feature in The Washington Post  pointed out that  existing vaccines to  potential bioterrorism agents were                       
“developed decades ago and can cause  severe side effects or even death” and  advised its readers against investing in  vaccine development.              Although acknowledging the risks, Warren Leary, writing in The New York Times, advocated voluntary  |vaccination against smallpox – “even if  only part of the population were  vaccinated, the bang for the terrorist’s  buck could be drastically curtailed”.             Meanwhile, ongoing efforts to  develop vaccines for the big killers –  HIV, malaria and tuberculosis – have  not hit the headlines. Although the  BBC World Service did report on a  “promising” new malaria vaccine  undergoing clinical trial in the Gambia.  The low-key tone was perhaps  appropriate given that the vaccine only  protected 47% of individuals. Another  report from the BBC News provided a  timely warning that “Weak vaccines  strengthen disease”. This story covered  
the predictions of Edinburgh based  epidemiologists that, in the case of  chronic diseases, such as malaria,  vaccines that are less than 100%  effective have the potential to do more  harm than good. Specifically, vaccines  that only protect a proportion of the  population could lead to outbreaks of  more virulent forms of disease and the  news article claims that this “could kill  more people that any vaccination  programme would save”.  

January 2002, Nature Reviews 
Immunology. Vol. 2  


Manufacturing snRNPs

Spinal muscular atrophy is genetic disease in which motor neurons in  the spinal cord degenerate. The protein  encoded by this gene is called survival  of motor neurons (SMN) and is one  component of the large multiprotein  SMN complex. Diverse cellular  processes rely on RNA-protein  assemblies, and the SMN complex  is  involved in the orderly construction of  the small nuclear ribonucleoprotein  particles (snRNPs) involved in pre- messenger RNA splicing.  
      Yong et al.  show that the SMN complex recognizes one of  the  four stem loops (SL1) of the U1 snRNA and that this region is necessary and sufficient for SMN complex interaction. A distinct region is responsible for gathering the Sm proteins, which form a heteroheptameric ring encircling the snRNA; together they comprise the core of the U1 snRNP. Some Sm proteins contain an Arg-Gly motif, and a separate complex, called  the methylosome, uses the protein methyltransferase PRMT5 to N-methylate the arginine symmetrically, as shown by Freisen et al. and Meister et al. The resulting dimethylarginine is recognized  by SMN, facilitating the supply of Sm proteins to the SMN complex.  

March 15,2002, Science Vol. 295


Mapping the fission yeast

Scientist have mapped all the genes of the fission yeast (Schizosaccharomyces pombe), which they hope will provide new insights into basic cell biology. An international team led by Paul Nurse of Cancer  Research Centre, the UK, has done the sequencing,  S. pombe is the sixth organism to have its genome sequenced. The others include humans, the nematode worm, the fruit fly and mustard weed. The sequencing is being considered significant as 50 of the 4,824 genes in the yeast are linked to human diseases such as cystic fibrosis, hereditary deafness, diabetes and cancer.

March 31, 2024 Down To Earth

Predicting  cancer  

A simple blood test might be used 
successfully to predict the chances of a person contracting lung cancer. Researchers at Columbia University, New York, USA, used blood samples that had been collected 13 years ago and found that people whose white blood cells were damaged were at a higher risk of getting cancer. According to the group of researchers, this damage is mainly due to exposure to polycyclic aromatic hydrocarbons (PAH), which binds to the genetic material. The group measured this bound PAH. While tobacco smoking releases PAH, they are also emitted from cars, power plants and during the process of cooking certain food. 

February  15, 2002 Down To Earth  


Were you born intelligent?

Recent research claims that the 
intellectual ability is influenced 
greatly by environment and may not be hereditary. Psychologist Dennis Garlick, of the University of Sydney in Australia, suggests that intelligence is created when neural connections in the  brain are changed in response to environmental cues. According to Garlick, recent advances in neuroscience and cognitive science have suggested that different intellectual abilities require different neural connections in the brain. Thus,  environmental conditions that allow  favourable connections to be developed lead to a better intellect.

February  15, 2002 Down To Earth


Lens solution is no solution  

Common types of contact lens solutions may leave behind remnants of a micro-organism that can cause a potentially serious eye infection, say Austrian researchers. They suggest that contact lens wearers doubly protect themselves by not only  disinfecting their lenses, but also ensuring that their contacts’ storage  cases are very clean. A multi-purpose solution and a one-step hydrogen  peroxide solution fails to expunge the tiny organism Acanthamoeba, that can  cause an inflammatory condition in the  cornea called keratitis. Infrequently, the infection can lead to blindness. 

April, 2002 Health Action     


Pressure tactics

Nearly nine out of 10 people who had acupuncture for physical ailments say the treatment relieved their pain, according to preliminary results of a large German study. The study, involving some 40,000 patients,  is the largest acupuncture study ever undertaken, according to the  researchers. Study coordinator Dr.  Hans-Joachim Trampisch from the  Ruhr-University of Bochum said that  in his opinion, previous studies on acupuncture did not involve enough  patients or were not conducted scientifically. “I am a medical  statistician,” he said. “I am not an  advocate of acupuncture.” Of the  patients in the study, almost 90 per  cent claimed that acupuncture  treatments had resulted in relief from  pain, according to a press release. Of  those patients, around half suffered  from back pain, and the rest from  headaches and a degenerative disease  of the joint. The average age of study  participants was around 58 years.

April, 2002 Health Action  

New rabies vaccine for India

The development of an indigenous cell culture vaccine for rabies at the Pasteur Institute of India at Coonoor, south India, promises to deliver a safe vaccine for the local population. Of the approximately 60,000 people who die of rabies annually worldwide, 3000 are from India alone.  The vaccine will be similar to the one called “Abhayrab” which was developed last year in Ootacamund  (also in south India) by the Human Biological Institute, a unit of the National Dairy Development Board. It is produced with the vero-cell lines as a substrate. These are cell lines derived from kidney cells of the vervet monkey. “Vero vaccines are considered to be safe by the WHO, with the recommendation that the DNA content of the vaccine be less than 300/pg/dose,” says S N Madhusudan, Associate Professor of Neurovirology at the National Institute of Mental Health and Neurosciences, Bangalore. Although there are no data  on the actual potency of the vaccine, Madhusudan is optimistic that it will be more than 2.5 IU/mL (the required potency).  “About half the rabies vaccines  used in India currently are the simple sheep-brain rabies vaccine” he adds. These vaccines are cheap, but are painful (ten subcutaneous injections of  5 ml each), and carry the rare but serious potential risk of demyelinaton. The imported vero cell line vaccines are commonly used in the cities but are more expensive at around  US$33 for the whole course. The new tissue culture vaccine on the other hand, should be available for about $ 15 since the Pasteur is a government institute that operates on a not-for- profit basis.

            September 2001, The Lancet


Warning on Serzone

The FDA has issued a warning that cases of life- threatening hepatic failure have been reported in patients using nefazodone hydrochloride   (Serzone, Bristol-Myers Squibb, Princeton, NJ), a treatment for depression. Patients taking Serzone should be advised to report signs and symptoms of liver dysfunction such as   jaundice, anorexia, or gastrointestinal   complaints to their physician  immediately. If they  develop evidence  of hepatocellular injury, such as increased serum aspartate aminotransferase or serum alanine at levels three times or higher than the upper limit of normal, they should be withdrawn from the drug and should not be considered for re-treatment.

March 6, 2024 JAMA  Vol. 287


Drug for pediatric liver disease

T he FDA has approved nitisinone capsules for use as an adjunct to dietary restriction of tyrosine and phenylalanine in the treatment of hereditary tyrosinemia type 1 (HT-1).             Nitisinone was studied in more   than 200 patients whose median age   was 9 months when therapy started.   The drug’s effectiveness was inferred   by its effect on reduction of   concentration of succinylacetone in  plasma and urine to a level below the   reference limit, and by normalization  of erythrocyte porphobilinogen   synthase activity. Resulting   improvements in these indices were   statistically significant (P<.001).              When the drug was combined with a restricted dietary intake of  tyrosine  and phenylalanine, the 4-year survival   rate of children under 2 months of age   at the time of diagnosis was 88%  compared with a survival rate of 29%   for children treated with dietary   restrictions alone. The most common adverse effects of nitisinone (such as corneal opacity, keratitis, and   photophobia, 2% each) were related to high tyrosine levels caused by dietary   indiscretion.

March 6, 2024 JAMA Vol. 287


Mango a valuable food medicine

The Mango is used as food in all stages of its development. Green or   unripe mango is a rich source of starch   and pectin and a fair source of vitamin   B1, B2  and niacin. It is sour in taste because of the presence of oxalic,  citric, malic and succiniac acids. The ripe fruit is very wholesome   and nourishing . The chief food  ingredient of mango is sugar. An  analysis of the ripe mango shows it to consist of moisture 81.10 %, Protein 0.6%, fat  0.4%, , fiber 0.7% and  carbohydrate 16.9% per 100 grams of   edible portion. Its mineral and vitamin   contents are calcium 14mg. %  phosphorus 16mg. %, iron 1.3mg.%,  carotene 2743mcg, thiamine 0.08mg,   riboflavin 0.09mg, niacin 0.9 mg. And   vitamin C 16.0 mg.% / 100 grams. The   average energy value of mango is  about 74 calories. The unripe fruit is acidic,   astringent and antiscorbutic. The ripe mango is antiscorbutic, diuretic,   laxative, invigorating, fattening and   astringent. It gives tone to the heart, improve complexion and stimulate appetite. The unripe mango protect from the adverse effects of hot, scorching winds. A drink prepared from the unripe mango by cooking it in hot ashes and mixing the pith with sugar and water, is an effective remedy for heat exhaution and heat stroke. Unripe green mangoes are   beneficial in the treatment of gastro- intestinal disorders. Eating one or two   mangoes in which seeds are not fully  formed with salt and honey is found to   be very effective medicine for summer   diarrhoea, dysentery, piles, morning sickness, chronic dyspepsia,  indigestion and constipation.   Ripe mangoes are beneficial in the   treatment of night blindness. Liberal use of mangoes during the season will   be very effective and will prevent   development of refractive errors, dryness of the eyes, softening of the   cornea, itching and burning in the eyes.  All bacterial invasions are due to  poor epithelium. Liberal use of   mangoes during the season contributes   towards formation of healthy  epithelium, there by preventing   frequent attacks of common infections   such as cold, rhinitis and sinusitis.   The tender leaves of the mango  tree are considered useful in diabetes.   An infusion is prepared for fresh leaves by soaking them overnight and   squeezing them well in water in the   morning. This filtrates should be taken   every morning to control early diabetes.

April 2000, Nisargopchar  Varta
Vol. 4