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Biomedical subjects

N Singh

Publications and source records attributed to N Singh.

At least 73 records · Page 4Linked to original sources
PubMed2002

Pyomyositis associated with bacillary angiomatosis in a patient with HIV infection.

Bacillary angiomatosis is an opportunistic infection occurring predominantly in patients with HIV infection. The manifestations of this vasculoproliferative disorder vary markedly. Virtually any organ site may be involved, singly or multiply. However cutaneous involvement can be a valuable clue to its diagnosis. We report a case of bacillary angiomatosis in an HIV-infected patient presenting as isolated pyomyositis of the right leg. The rarity of such a presentation and paucity of cutaneous lesions, as in our case, may render timely diagnosis elusive and difficult. Its recognition however, is important since bacillary angiomatosis, if untreated, is potentially fatal.

AIDS-Related Opportunistic Infections↗
PubMed2002

Usefulness of an inexpensive, Paracheck test in detecting asymptomatic infectious reservoir of plasmodium falciparum during dry season in an inaccessible terrain in central India.

OBJECTIVES: The performance of a new indigenous rapid diagnostic test, Paracheck Pf was evaluated in detection of Plasmodium falciparum in asymptomatic children in remote forest villages of Mandla district, central India to determine the lower limits of sensitivity and specificity of rapid test. METHODS: A finger prick blood sample was collected to prepare blood smear and for testing with the Paracheck test. The blood smears were read by an experienced technician blinded to the Paracheck results. The figures for specificity, sensitivity, accuracy and predictive values were calculated using microscopy as gold standard. RESULTS: The new diagnostic test had a sensitivity of 94% and a specificity of 89%. The positive and negative predictive values were 71% and 98%, respectively. The J -index was 0.83%. CONCLUSION: The rapid test was found to be very easy to perform and the result could be read reliably by field workers. The field evaluation with this new inexpensive test, ($0.65/test) indicates that it could be used as an epidemiological tool in the management of malaria particularly in areas where microscopy is not operationally feasible to attain the goal of the roll back malaria initiative.

Adolescent↗
PubMed2002

Effect of prenatal auditory enrichment on developmental expression of synaptophysin and syntaxin 1 in chick brainstem auditory nuclei.

Neural activity plays an important role in shaping the developing brain. We have determined the consequence of increased auditory stimulation on the developmental profile of synaptic proteins, synaptophysin and syntaxin 1, in the chick brainstem auditory nuclei, nucleus magnocellularis and nucleus laminaris, by immunohistochemistry and western blotting techniques. The chick embryos were provided with patterned sounds of species-specific calls or musical notes of a sitar, a stringed instrument, in a graded manner from embryonic day 10 (E10) through hatching, for 15 min every hour. During normal synaptogenesis of nucleus magnocellularis and nucleus laminaris, synaptophysin immunoreactivity increased significantly from E8 to E20, in parallel with synapse formation, and reduced at hatching. The embryos receiving species-specific sound stimuli exhibited a similar pattern with higher levels of immunoreactivity, though the difference between the study groups was not statistically significant. The music stimulated embryos showed an earlier peak at E16, followed by a gradual decline until hatching. In all three groups studied, syntaxin immunoreactivity showed a surge at E12, followed by a decline at E16 and subsequent stabilization. The stimulated groups continually expressed higher amounts of syntaxin immunoreactivity. The results suggest that prenatal sound stimulation enhances the normal pattern of synaptic protein expression in these auditory nuclei.

Acoustic Stimulation↗
PubMed2002

Chronic epididymitis (epididymal nodule) mimicking an adenomatoid tumor--case report with review of literature.

AIM: To describe and review the differential diagnosis of epididymal nodules and chronic epididymitis so as to have a broad view of this pathology. We have suggested a possible diagnostic algorithm for the workup of an epididymal nodule. METHODS/RESULTS: We have reported a case of a 35-year-old patient with a symptomatic palpable nodular mass in the tail of the left epididymis. Fine needle aspiration suggested an adenomatoid tumor while the surgical excision histology was reported as chronic epididymitis. CONCLUSIONS: Epididymal nodules are frequently encountered in the epididymis. Their differential diagnosis includes chronic granulomatous epididymitis, adenomatoid tumor and benign paratesticular neoplasms. We consider that it is important to distinguish epididymal nodules from benign inflammatory lesions and the threshold for a surgical excision should be low as it is therapeutic and provides a definite diagnosis. Whilst the FNAC alone may not be always adequate to confirm diagnosis, an epididymectomy may be curative as well as diagnostic in selected cases.

Adenomatoid Tumor↗
PubMed2002

Amylase hyperproduction by deregulated mutants of the thermophilic fungus Thermomyces lanuginosus.

Thermomyces lanuginosus was subjected to three cycles of mutagenesis (UV/NTG) and a selection procedure to develop amylase-hyperproducing, catabolite-repression-resistant and partially constitutive strains. One of the selected derepressed mutant strain III(51), produced approximately 7- and 3-fold higher specific activity of alpha-amylase (190 U/mg protein) and glucoamylase (105 U/mg protein), respectively, compared to a wild-type parental strain. Further, the effect of production parameters on mutant strain III(51) was studied using a Box-Behnken design. The regression models computed showed significantly high R(2) values of 96 and 97% for alpha-amylase and glucoamylase activities, respectively, indicating that they are appropriate for predicting relationships between corn flour, soybean meal and pH with alpha-amylase and glucoamylase production.

Amylases↗
PubMed2002

Serum sialic acid, a possible cardiovascular risk factor is not increased in Fijian Melanesians with impaired glucose tolerance or impaired fasting glucose.

BACKGROUND: Serum total sialic acid (TSA) has been shown to be a strong cardiovascular risk factor with increased concentrations being associated with increased mortality. Serum TSA is also elevated in patients with type 2 diabetes including those with micro- and macrovascular complications. We wished, therefore, to test the hypothesis that serum TSA may be abnormal in individuals with impaired glucose tolerance (IGT) and impaired fasting glucose (IFG), in Fijian Melanesians. METHOD: Twenty-one subjects with IGT (17 women and four men) were recruited along with 20 subjects with IFG (14 women and six men) and 22 normal subjects (12 women and 10 men). Serum TSA was 2.18 +/- 0.027 mmol//L, 2.19 +/- 0.033 mmol/L and 2.24 +/- 0-042 mmol/L in the three groups, respectively, which was not statistically different. Both systolic and diastolic blood pressure were, however, higher in the IGT group compared with the IFG and normal groups (P<0.04). CONCLUSION: Serum TSA is not elevated in Fijian Melanesians with IGT and IFG although it is reported to be elevated in type 2 diabetes mellitus in other populations. Further research is needed to establish why serum TSA is a potent independent cardiovascular risk factor and is elevated in type 2 diabetes mellitus in some populations.

Adult↗
PubMed2002

Patterns of rainfall and malaria in Madhya Pradesh, central India.

Some recent outbreaks of Plasmodium falciparum malaria have been attributed, at least in part, to increases in the intensity and duration of rainfall caused by the El Niño southern oscillation (ENSO), a periodic climatic phenomenon. Since it takes time for unusually heavy rainfall to translate into unusually high densities of the vector mosquitoes, it has been suggested that data on recent rainfall might be used to predict climate-related epidemics of malaria. This possibility was explored by comparing the patterns in the incidence of malaria in (1) Dungaria, a highly malarious village in the central-Indian district of Mandla, and (2) Mandla district as a whole, for the periods 1986-2000 and 1967-2000, respectively, with data on rainfall for the same areas and periods. Unfortunately, no clear relationship was observed between rainfall and malaria incidence, although a major development project to improve water resources in the study area (which resulted in local villages being partially or completely submerged in water) may have masked any significant association. A useful method for predicting which years are going to be high- or low-risk years for malaria epidemics, in the present and other epidemiological settings, remains a future goal.

Climate↗
PubMed2002

Hepatorenal syndrome: pathophysiology and treatment.

The hepatorenal syndrome (HRS) is a unique form of acute renal failure with entirely normal renal histology in advanced liver disease. Its diagnosis is made by exclusion of all causes of renal failure and by all the five major criteria as set by the International Ascites Club. The presence of hepatomegaly, poor nutritional status, and oesophageal varices at endoscopy are associated with a high risk of HRS. The liver tests, the Child-Pugh score, are of no value in prediction of its occurrence. Contraction of the effective blood volume, which may lead to renal hypoperfusion with preferential renal cortical ischaemia, is proposed pathogenesis of the condition. Because understanding of the pathogenesis of HRS is incomplete, therapy is supportive only. Optimal fluid management is vital as there is almost invariably a reduction in effective arterial blood volume. Dopamine, frusemide and haemofiltration may be helpful in management of fluid overload but do not affect renal function. TIPS has been used successfully in small series of patients. The vasopressin analog also has been used with early excellent response. The treatment of HRS has been discouraging and the only proven cure for HRS is liver transplantation at this point of time.

Hepatorenal Syndrome↗
PubMed2001

Lactoferrin-melanin interaction and its possible implications in melanin polymerization: crystal structure of the complex formed between mare lactoferrin and melanin monomers at 2.7-A resolution.

The concentration of melanin determines the intensity of colors of the skin and hair of animals. Melanin pigments are tyrosine-based polymers formed in melanocytes within specialized organelles called melanosomes. In order to understand the mechanism of melanin polymerization, lactoferrin, a basic protein with a pI value of 9.0, has been used to produce melanin. Lactoferrin is a monomeric iron-binding protein with a molecular weight of 80 kDa. The crystals of lactoferrin were soaked in a solution containing dihydroxyphenylalanine (DOPA) and tyrosinase enzyme. These crystals were used for X-ray intensity data collection. The intensity data were collected to 2.7-A resolution to an overall completeness of 91% with an R(sym) of 0.071. The crystals belong to orthorhombic space group P2(1)2(1)2(1) with cell dimensions: a = 85.0 A, b = 99.8 A, c = 103.4 A. The structure was determined by molecular replacement method, using the model of diferric mare lactoferrin, and refined to an R-factor 0.215 (R(free) = 0.287) for all the data to 2.7-A resolution. The final model comprises 5,281 protein atoms from 689 amino acids, 2Fe(3+), 2CO(2-)(3) ions, 2 indole-5,6-quinone molecules (IQ), and 73 water molecules. Two IQ molecules, one in each lobe, bind to lactoferrin. In the C-lobe, the IQ binds in the iron-binding cleft, whereas in the N-lobe, it is located in the side pocket between two alpha-helices, filled with solvent molecules in the native iron-saturated mare lactoferrin. The IQ molecules interact with protein molecule mainly through glutamic acid in both lobes, without significant perturbation to the protein structure. The orientation of N- and C-lobes in the present structure is similar to that observed in the native iron-saturated protein. However, as a result of the binding of IQ molecules, the orientations of the domains N1, N2 and C1, C2 in the two cases differ slightly.

Animals↗
PubMed2001

Asynchronous replication and allelic exclusion in the immune system.

The development of mature B cells involves a series of molecular decisions which culminate in the expression of a single light-chain and heavy-chain antigen receptor on the cell surface. There are two alleles for each receptor locus, so the ultimate choice of one receptor type must involve a process of allelic exclusion. One way to do this is with a feedback mechanism that downregulates rearrangement after the generation of a productive receptor molecule, but recent work suggests that monoallelic epigenetic changes may also take place even before rearrangement. To better understand the basis for distinguishing between alleles, we have analysed DNA replication timing. Here we show that all of the B-cell-receptor loci (mu, kappa and lambda) and the TCRbeta locus replicate asynchronously. This pattern, which is established randomly in each cell early in development and maintained by cloning, represents an epigenetic mark for allelic exclusion, because it is almost always the early-replicating allele which is initially selected to undergo rearrangement in B cells. These results indicate that allelic exclusion in the immune system may be very similar to the process of X chromosome inactivation.

Alleles↗
PubMed2001

Trends in the epidemiology of opportunistic fungal infections: predisposing factors and the impact of antimicrobial use practices.

In the past decade, the frequency of opportunistic fungal infections has increased, and the spectrum of fungal pathogens has changed. The increasing number of susceptible hosts, the introduction of newer modalities for hematopoietic stem cell transplantation, the evolution of organ transplantation practices, the use of novel immunosuppressive agents, and current antimicrobial prophylactic strategies have likely contributed to the changing epidemiology of invasive mycoses. The introduction of azoles more than a decade ago has had a profound impact on curtailing candidal infections. However, a dramatic increase in azole-resistant Candida species and mold infections has been documented. The trends in time of onset, spectrum, and frequency of infections due to invasive molds and opportunistic yeasts are unique for different fungi and vary between subsets of immunocompromised hosts. This review discusses the implications of these trends for guiding judicious use of antimicrobial prophylactics and for unraveling the pathophysiological basis of fungal infections.

Antifungal Agents↗