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Biomedical subjects

M Krishnan

Publications and source records attributed to M Krishnan.

At least 19 recordsLinked to original sources
PubMed2002

Knowledge and practice of breast cancer screening amongst public health nurses in Singapore.

AIM OF STUDY: The study aimed to examine the knowledge and practice of breast cancer screening amongst Public Health nurses who are patient educators. METHOD: A self-administered questionnaire was sent to all 447 nurses in the Public Health Service to assess their knowledge and practice of breast cancer screening. Response rate was 96.4%. Knowledge scores ranged from 0-17 with one point given to a correct knowledge question, zero for wrong answer. RESULTS: Median knowledge score was nine and 58.3% of nurses scored > or = 9. Statistically significant factors influencing knowledge scores were related to the nursing profession, namely nursing qualifications, current nursing post and current workplace. 76.2% of Nursing Officers/Higher Nursing Officers and 74.5% of midwives had knowledge scores > or = 9 compared with 57.3% of staff nurses and 40.8% of assistant nurses (p < 0.01). 60.1% of nurses who were taught breast-self examination scored > or = 9 (p < 0.05). As for practice, 93.7% of nurses did breast-self-examination, 54.1% had clinical breast examination in the past one year and 50.2% had mammogram done. On multivariate analysis, significant factors affecting practice of clinical breast examination were marital status (Prevalence Rate Ratio 1.94, 95% Confidence Interval 1.20-3.15), doctor's gender (PRR 1.35, CI 1.04-1.75) and those affecting mammogram were age group (PRR 1.78, CI 1.27-2.48), marital status (PRR 1.63, CI 1.03-2.59), history of breast disease (PRR 1.51, CI 1.06-2.16). CONCLUSIONS: The majority of nurses had certain misconceptions in the knowledge of breast cancer and breast cancer screening. A higher proportion of nurses in the Family Health Service had higher knowledge scores than other nurses in the Public Health Service. Most of the nurses did breast-self-examination. Having ever married and the availability of a female doctor influenced the nurses attending clinical breast examination. Nurses who were > or = 50 years old, ever married and those with a positive history of breast disease were more likely to have mammography done.

Adult↗
PubMed2001

Microfabricated reaction and separation systems.

Over the past year there have been a number of recent advances in the fields of miniaturized reaction and separation systems, including the construction of fully integrated 'lab-on-a-chip' systems. Microreactors, which initially targeted DNA-based reactions such as the polymerase chain reaction, are now used in several other chemical and biochemical assays. Miniaturized separation columns are currently employed for analyzing a wide variety of samples including DNA, RNA, proteins and cells. Although significant advances have been made at the component level, the realization of an integrated analysis system still remains at the early stages of development.

Automation↗
PubMed2001

Evolution and characterization of tetraonine endogenous retrovirus: a new virus related to avian sarcoma and leukosis viruses.

In a previous study, we found avian sarcoma and leukosis virus (ASLV) gag genes in 19 species of birds in the order Galliformes including all grouse and ptarmigan (Tetraoninae) surveyed. Our data suggested that retroviruses had been transmitted horizontally among some host species. To further investigate these elements, we sequenced a replication-defective retrovirus, here named tetraonine endogenous retrovirus (TERV), from Bonasa umbellus (ruffed grouse). This is the first report of a complete, replication-defective ASLV provirus sequence from any bird other than the domestic chicken. We found a replication-defective proviral sequence consisting of putative Gag and Env proteins flanked by long terminal repeats. Reverse transcription-PCR analysis showed that retroviral gag sequences closely related to TERV are transcribed, supporting the hypothesis that TERV is an active endogenous retrovirus. Phylogenetic analyses suggest that TERV may have arisen via recombination between different retroviral lineages infecting birds. Southern blotting using gag probes showed that TERV occurs in tetraonines but not in chickens or ducks, suggesting that integration occurred after the earliest phasianid divergences but prior to the radiation of tetraonine birds.

Amino Acid Sequence↗
PubMed2001

Abdominal thrombotic and ischemic manifestations of the antiphospholipid antibody syndrome: CT findings in 42 patients.

PURPOSE: To determine the abdominal computed tomographic (CT) findings in patients with antiphospholipid antibody syndrome (APS). MATERIALS AND METHODS: Retrospective review of medical records from two university medical centers from 1994 through 1997 revealed 215 patients who had a hypercoagulable state attributed to primary or secondary APS. Abdominal CT findings in these patients were reviewed for evidence of large-vessel occlusion or visceral ischemia. RESULTS: In 42 (19.5%) of 215 patients with APS (age range, 32-65 years; mean age, 42 years), abdominal thromboses or ischemic events were detected at CT. Twenty-two (52%) had major vascular thromboses, including those in the inferior vena cava (n = 10), portal and superior mesenteric veins (n = 7), splenic vein (n = 4), and aorta (n = 1). Thirty-six (86%) patients had abdominal visceral ischemia resulting in renal infarction (n = 22), bowel ischemia (n = 13), splenic infarction (n = 6), pancreatitis (n = 3), hepatic infarction (n = 1), and/or hepatic dysfunction with portal hypertension (n = 1). In some patients, more than one abdominal organ and/or vessel was involved. CONCLUSION: Patients who have circulating antiphospholipid antibodies are at risk for major abdominal vascular thromboses and organ infarction. Radiologists must be familiar with this syndrome; they may be the first physicians to suggest the diagnosis on the basis of findings of unusual or recurrent sites of thrombosis, especially in young patients.

Abdomen↗
PubMed2000

FTIR-ATR spectroscopy for monitoring polyanhydride/anhydride-amine reactions.

The reactivity of 1,3-bis(p-carboxyphenoxy) propane:sebacic acid anhydride copolymer (CPPSA1:6), myristic and benzoic anhydrides with amine nucleophiles were investigated in non-polar solvents. FTIR-ATR (attenuated total reflectance) spectroscopy was used to monitor the polyanhydride/anhydride reaction rates in dichloromethane, dichloroethane, chloroform, and 1,4-dioxane solutions at room temperature. The reaction kinetics was determined by measuring the anhydride peak loss with time. Aminolysis resulted from nucleophilic attack of the added amine on the carbonyl group of the anhydride moiety. Primary and secondary amines reacted to form amides and the reaction followed second-order kinetics. Second-order rate constants and reaction half-life (t(1/2)) were calculated from the semilog plots of [anhydride]/[amine] in 1,4-dioxane at room temperature. The aminolysis rate decreased with pK(a) of the amine reactant, and half-life (t(1/2)) decreased with increasing amine concentration, as expected. With trifluoroethylamine (pK(a) 5.8), myristic anhydride reacted about 6-fold faster than benzoic anhydride. The lower reaction rate of benzoic anhydride was due to the higher stability of the aromatic anhydride compared to aliphatic. The overall CPPSA1:6 copolymer reactivity was the sum of aliphatic-aliphatic (SA-SA), aliphatic-aromatic (SA-CPP), and aromatic-aromatic (CPP-CPP) anhydride linkage reactivities. Based on the monomer ratio, the probability of SA-SA, SA-CPP, and CPP-CPP dyads were calculated to be 0.74, 0.24, and 0.02, respectively. This indicated that CPPSA1:6 reactivity will mainly result from SA-SA and SA-CPP linkages. The second-order rate constants and t(1/2) obtained for CPPSA1:6 with TFEA were closer to those for myristic anhydride than benzoic anhydride with TFEA.

Algorithms↗
PubMed2000

Electron acceleration and the propagation of ultrashort high-intensity laser pulses in plasmas

Reported are interactions of high-intensity laser pulses ( lambda = 810 nm and I</=3x10(18) W/cm(2)) with plasmas in a new parameter regime, in which the pulse duration ( tau = 29 fs) corresponds to 0. 6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degrees is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results.

Journal Article↗
PubMed2000

Cospeciation and horizontal transmission of avian sarcoma and leukosis virus gag genes in galliform birds.

In a study of the evolution and distribution of avian retroviruses, we found avian sarcoma and leukosis virus (ASLV) gag genes in 26 species of galliform birds from North America, Central America, eastern Europe, Asia, and Africa. Nineteen of the 26 host species from whom ASLVs were sequenced were not previously known to contain ASLVs. We assessed congruence between ASLV phylogenies based on a total of 110 gag gene sequences and ASLV-host phylogenies based on mitochondrial 12S ribosomal DNA and ND2 sequences to infer coevolutionary history for ASLVs and their hosts. Widespread distribution of ASLVs among diverse, endemic galliform host species suggests an ancient association. Congruent ASLV and host phylogenies for two species of Perdix, two species of Gallus, and Lagopus lagopus and L. mutus also indicate an old association with vertical transmission and cospeciation for these ASLVs and hosts. An inference of horizontal transmission of ASLVs among some members of the Tetraoninae subfamily (grouse and ptarmigan) is supported by ASLV monophyletic groups reflecting geographic distribution and proximity of hosts rather than host species phylogeny. We provide a preliminary phylogenetic taxonomy for the new ASLVs, in which named taxa denote monophyletic groups.

Animals↗
PubMed2000

RH-5992--an ecdysone agonist on model system of the silkworm Bombyx mori.

RH-5992 is a novel synthetic non-steroidal ecdysteroid agonist with a high selectivity towards Lepidopteran species. The effect of ecdysone agonist RH-5992 on larval period, larval weight, silk gland weight and haemolymph protein profile were examined in the model organism, the larvae of silkworm, Bombyx mori. The LD50 values were found to be 16.21 and 12.01 micrograms/larva for 72 and 96 hr respectively. In the present study, three sublethal concentrations of 1/5th, 1/10th and 1/20th of LD50 at 72 hr were selected and applied on the mid-dorsal line of the silkworm B. mori. The maximum mortality of 35% was observed in the group which received the highest (3.2 micrograms/larva) concentration of RH-5992. The mortality rate was found to be dose dependent as well as time dependent. Interesting results were observed in haemolymph profile of the RH-5992 treated larvae as staining intensity of 30 kDa protein decreased significantly whereas the effect was not marked on other major proteins like storage proteins and vitellogenin polypeptides. From the results, it is confirmed that RH-5992 causes changes in larval characters and protein profile of silkworm B. mori. It is proposed that RH-5992 may cause negative effect specifically on reproductive characters like development of ovary and egg production due to decrease in 30 kDa protein.

Animals↗
PubMed1999

The murine clan V(H) III related 7183, J606 and S107 and DNA4 families commonly encode for binding to a bacterial B cell superantigen.

Superantigens, by virtue of their unconventional binding interactions with Ag receptors, can simulate a large subset of mature lymphocytes in the repertoire. Recent studies have documented that in vivo exposure to the model bacterial B cell superantigen, Staphylococcal protein A (SpA), induces large scale effects on murine B-cell clonal selection by mechanism(s) that include deletion of supra-clonal sets. While the structural bases for the immunomodulatory properties of several T-cell superantigens have been well characterized, the requirements for murine Fab-binding of SpA remain incompletely defined. To investigate these structural requirements, a series of direct binding and inhibition studies were performed with a large panel of Moabs of diverse variable region gene usage. These studies confirm previous reports that superantigen binding is completely restricted to the products of clan V(H) III-related families, that include the small S107 and J606 families, and we also demonstrated that usage of the related small DNA4 family commonly correlates with weaker binding activity. Furthermore, our results document that genes from the largest clan V(H) III family, 7183, commonly encode for Fab-mediated binding of SpA, while antibodies from five other VH families, J558, Q52, Sm7, VH11 and VH12, did not display Fab-mediated SpA binding activity. By contributing to the essential foundation for understanding of the structural basis for binding interactions, these findings will aid interpretation of evolving observations regarding the clonal fates induced by in vivo B-cell superantigen exposure.

Amino Acid Sequence↗
PubMed1999

Post traumatic rupture of the right main bronchus: a rare clinical entity?

Tracheobronchial disruption is an uncommon injury usually associated with severe blunt thoracic trauma and rarely occurs in isolation. We report a case of isolated rupture of the right main bronchus occurring after a crush injury without an associated pneumothorax. Difficulties in the diagnosis of this condition are briefly discussed and an algorithm of management presented.

Bronchi↗
PubMed1999

Changes in embryonic protein profile and economic characters of Bombyx mori (Lepidoptera:Bombycidae) following UV irradiation.

Eggs of B. mori were irradiated with UV (254.4 nm wavelength) for different durations. Increase in the time of exposure to UV decreased the percentage hatchability of the eggs, cocoon and pupal weights. The shell weight remained unaltered proving the stability of silk gland DNA. Irradiation of eggs also delayed the degradation/utilization of the embryonic proteins, viz. vitellin (heavy and light subunits), egg-specific protein and 30K protein.

Animals↗
PubMed1998

An integrated nanoliter DNA analysis device.

A device was developed that uses microfabricated fluidic channels, heaters, temperature sensors, and fluorescence detectors to analyze nanoliter-size DNA samples. The device is capable of measuring aqueous reagent and DNA-containing solutions, mixing the solutions together, amplifying or digesting the DNA to form discrete products, and separating and detecting those products. No external lenses, heaters, or mechanical pumps are necessary for complete sample processing and analysis. Because all of the components are made using conventional photolithographic production techniques, they operate as a single closed system. The components have the potential for assembly into complex, low-power, integrated analysis systems at low unit cost. The availability of portable, reliable instruments may facilitate the use of DNA analysis in applications such as rapid medical diagnostics and point-of-use agricultural testing.

Costs and Cost Analysis↗
PubMed1998

Immunodominant peptide epitopes of allergen, Asp f 1 from the fungus Aspergillus fumigatus.

Aspergillus fumigatus ribotoxin Asp f 1 is a major allergen with IgE binding activity to serum of a majority of patients with allergic bronchopulmonary aspergillosis (ABPA). The IgE binding epitopes or the T-cell stimulatory peptides of this molecule have not been studied. In the present investigation, we have synthesized linear decapeptides spanning the whole molecule of Asp f 1 and analyzed their IgE binding properties. We have also synthesized peptides based on their possible T-cell stimulatory properties and studied the stimulation of peripheral blood mononuclear cells from ABPA patients and normal controls. Several peptides demonstrated distinct IgE antibody binding response against sera from ABPA patients and proliferative response against peripheral blood mononuclear cells from the patients. From the results, it can be concluded that the carboxy-terminal region of Asp f 1 representing amino acid residues 115-149 involved in both humoral and cell mediated immunoresponses in ABPA.

Allergens↗
PubMed1997

Effect of mifepristone on folliculogenesis in women treated with recombinant FSH.

OBJECTIVE: To study the mechanism through which mifepristone interrupts folliculogenesis. DESIGN: Normally ovulating women undergoing donor intrauterine insemination (IUI) treatment were investigated during two menstrual cycles treated with gonadotrophins. In the first cycle (FSH cycle), the women were given 150 IU recombinant FSH (rFSH) s.c. on days 2, 4, 6, 8 and daily thereafter until the administration of hCG. During the second cycle (FSH + mifepristone cycle), the women received rFSH as above plus mifepristone tablets at a dose of 50 mg/day from cycle day 2 until the hCG injection. IUI was performed only in the FSH cycles. PATIENTS: Eleven normally ovulating women were studied. The women were used as their own controls during the cycle treated with rFSH only. RESULTS: Two women became pregnant during the FSH cycle and, therefore, data for comparison between the two cycles were available in nine women. In both cycles, only one follicle reached the preovulatory stage. However, during treatment with FSH + mifepristone the growth of the dominant follicle was temporarily arrested after day 8 of the cycle and ovulation was postponed by 2 days on average. Serum FSH values increased significantly in both cycles only during the daily administration of rFSH, i.e. towards the end of the experimental period when a normal growth of the follicle was re-established. On the day of hCG injection, an endogenous LH surge had already started in six of the nine cycles treated with FSH (67%) but in none of the FSH + mifepristone cycles despite the preovulatory oestradiol (E2) levels. Endometrial thickness during the follicular phase and serum E2 and progesterone concentrations during the luteal phase, although in the normal limits, were significantly lower in the FSH + mifepristone than in the FSH cycles. CONCLUSIONS: These results suggest that mifepristone arrests follicular development at a stage beyond the recruitment-selection point by delaying the growth of the dominant follicle. This is probably achieved through an effect of mifepristone on the ovary where it reduces the sensitivity of the selected follicle to FSH. Mifepristone may have a potential application for the inhibition of the LH surge in superovulation induction programmes.

Adult↗