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Biomedical subjects

Mamta Sharma

Publications and source records attributed to Mamta Sharma.

17 recordsLinked to original sources
PubMed2006

Erythrophagocytosis in sickle cell anemia: statistical evidence for a biological phenomenon.

The precise role of erythrophagocytosis in sickle cell disease is not known. Using hematological data from three studies and 791 subjects comprising of eight epidemiological groups, we found a strong statistical support for the hypothesis that erythrophagocytosis is increased in sickle cell trait, that neutrophils and lymphocytes are the most likely cells involved in erythrophagocytosis in these subjects and that increased erythrophagocytosis may for a mechanistic explanation for an increased risk of vaso-occlusive crisis in sickle cell trait. Statistically, erythrophagocytosis was not increased in subjects with homozygous sickle cell disease. Our findings offer an interesting mechanistic implication about the presence of a strong autoimmune component of sickle cell trait that can be explained by the well recognized interplay between the receptor molecule signal regulatory protein-alpha (SIRP-alpha) on the phagocyte and its ligand, CD47, on the red blood cell. Our findings also support further and closer evaluation of the other hypothesized mechanisms by which neutrophils and lymphocytes partake in differential degree of erythrophagocytosis in subjects heterozygous for the sickle hemoglobin. Finally, translation of these findings into a clinical realm suggests that the extent of erythrophagocytosis, as measured by peripheral blood hematological indicators, can serve as an important indicator of the likelihood of future vaso-occlusive crisis events in subjects of sickle cell trait.

Anemia, Sickle Cell↗
PubMed2006

Insights into age- and sickle-cell-disease-interaction using principal components analysis.

BACKGROUND: In the context of sickle cell anemia, peripheral blood indexes provide key information that is also potentially influenced by age. Therefore, it is necessary to understand the extent and nature of interactions between sickle cell anemia and age, especially in situations where there is a high prevalence of sickle cell anemia. METHODS: In a cross-sectional study of 374 subjects with varying hemoglobin S (HbS) status, we characterized the interaction between age and sickle hemoglobin using principal components analysis. RESULTS: Factor analysis in subjects with hemoglobin AA identified three orthogonal factors--normal erythropoiesis, presence of thalassemia and the aggregability potential of the blood. These three factors were differentially associated with hemoglobin status. Age influenced the association of factors #2 and #3 with hemoglobin status. CONCLUSION: Our findings suggest that the interaction between age and hemoglobin status needs to be considered in both clinical and public health settings.

Journal Article↗
PubMed2006

Persistence in Staphylococcus aureus bacteremia: incidence, characteristics of patients and outcome.

Staphylococcus aureus bacteremia often persists. The reasons for persistence and its outcome are poorly defined. We conducted a prospective-observational study among 245 consecutive S. aureus (MRSA: n=125; MSSA: n=120) bacteremias (>or=1 positive blood cultures (BC)) among 234 adults (18-103-y-old; median=59 y) hospitalized during 1 January 2002-31 December 2002 at a 600-bed teaching hospital. Measurements included bacteremia duration, complication-rate (metastatic infection, relapse or attributable mortality) and outcome. Bacteremia duration was measured based on follow-up BC among 193 patients and estimated based on symptoms resolution in the rest. Measured (1-59 d; median=2) and estimated (median=1 d) duration correlated (r=0.885) though positive follow-up BC was often detected without fever (57/105 patients, 54.3%). Persistence (defined as bacteremia for >or=3 d) was noted in 84 cases (38.4%). Complication-rate increased steadily with bacteremia duration (6.6%, 24.0% and 37.7% in bacteremia for 1-2, 3 and >or=4 d, respectively; p=0.05). Cox regression analysis revealed that bacteremia duration correlated positively with endovascular sources (p=0.006), vancomycin treatment (p=0.016), cardiovascular prosthesis (p=0.025), metastatic infections (p=0.025) and diabetes (p=0.038). It is concluded that persistent bacteremia is a feature of S. aureus infection, irrespective of oxacillin susceptibility, associated with worse outcome. Risk factors include endovascular sources, cardiovascular prosthesis, metastatic infections, vancomycin treatment and diabetes. Patients at risk may benefit from novel treatment strategies.

Adolescent↗
PubMed2005

In-situ degradation of sulphur mustard and its simulants on the surface of impregnated carbon systems.

Bis-2-chloroethyl sulphide (sulphur mustard or HD) is an extremely toxic and persistent chemical warfare agent. For in situ degradation of HD and its analogues (simulants), i.e., dibutyl sulphide (DBS) and ethyl 2-hydroxyethyl sulphide (HEES), different carbon systems such as 11-molybdo-1-vanadophosphoric acid impregnated carbon (V(1)/C), ruthenium chloride impregnated carbon (Ru/C) and combination of these two (V(1)/Ru/C) were prepared. These carbons were characterized for cumulative micropore volume and surface area by N(2) BET. The kinetics of the in situ degradation of HD and its simulants were studied and found to be following the first order kinetics. Kinetic rate constants and t(1/2) values were determined. Products were characterized using NMR, IR and GC-MS. Reaction products were found to be sulphoxide and sulphone. The combined system, i.e., 11-molybdo-1-vanadophosphoric acid plus ruthenium chloride (V(1)/Ru/C) was found to be best for in-situ degradation of HD and its simulants. In-situ degradation by polyoxometalate based system was found to be stoichiometry based while Ru/C oxidized HD in presence of chemisorbed oxygen. In combined system of V(1)/Ru/C ruthenium worked as a catalyst and polyoxometalate acted as a source of oxygen. Effect of moisture was also studied in combined system. Rate of degradation of HD was found to be increasing with increased percentage of moisture content.

Carbon↗
PubMed2005

Time to positivity in Staphylococcus aureus bacteremia: possible correlation with the source and outcome of infection.

BACKGROUND: Staphylococcus aureus bacteremia often persists and causes metastatic infections. It is unknown whether the time between blood culture incubation and growth detection (i.e., the time to positivity) in a continuously monitored system--a probable surrogate marker of bacteremia severity--correlates with outcome. METHODS: We performed a prospective, observational study involving adult inpatients who had S. aureus bacteremia between 1 January 2002 and 30 June 2003 at a 600-bed teaching hospital. Measurements included time to positivity in initial blood culture series, duration of bacteremia, rate of metastatic infection, and outcome. RESULTS: A total of 376 S. aureus bacteremias (> or = 1 positive blood culture result) were reported for 357 patients aged 18-103 years (median age, 59 years); 64 bacteremias were excluded because blood was drawn after antibiotic therapy was started (n = 59) or through an intravascular catheter (n = 5). The source of infection was identified in 244 series (78.2%). Metastatic infection was detected in 25 bacteremias (8.0%). The mortality rate was 25.6%. The duration of bacteremia (determined in 251 series) was 1-59 days (median duration, 1 day; 70th percentile, 3 days). The time to positivity ranged from 4.2 to 98.2 h (median time to positivity, 15.5 h) and was significantly shorter for patients with an endovascular source of infection (14.9+/-5.4 vs. 19.5+/-10.6 h; P < .0005), extended duration (i.e., > or = 3 days) of bacteremia (14.1+/-4.2 vs. 18.6+/-9.2 h; P < .0005), and metastatic infection (12.9+/-5.9 vs 18.0+/-9.3 h; P = .007). Analysis of a range of cutoff values demonstrated that a time to positivity of < or = 14 h yielded the best sensitivity and specificity for predicting the source and outcome of infection. Logistic regression analyses revealed that a time to positivity of < or = 14 h was an independent predictor of an endovascular source of infection (P < .0005), extended bacteremia (P < .0005), metastatic infection (P < .0005), and attributable mortality (P = .017). CONCLUSIONS: Time to positivity in S. aureus bacteremia may provide useful diagnostic and prognostic information. Growth of S. aureus within 14 h after the initiation of incubation may identify patients with a high likelihood of endovascular infection sources, delayed clearance, and complications.

Adolescent↗
PubMed2005

Favorable prognosis of Staphylococcus aureus bacteremia originating from soft tissues: a prospective study of fifty cases.

Staphylococcus aureus bacteremia often causes metastatic infection and endocarditis. The incidence of these complications in soft tissue-associated bacteremia is not well defined. We conducted a prospective observational study of all adult in patients with S. aureus bacteremia originating from soft tissues from 1 January 2002 to 30 June 2003, in a 600-bed teaching hospital. 376 patients with > or =1 positive blood cultures for S. aureus were encountered; 50 (13.3%) had a soft tissue source, and 46% were nosocomial. Age was 21-103 y (median 60 y). The majority (96%) had comorbid conditions. Predisposing factors such as surgery, trauma and miscellaneous skin conditions were common (88%). Oxacillin-resistant isolates accounted for 26 cases (52%). Metastatic infections were uncommon (6%). Duration of bacteremia was 1-13 d (median 1 d). Bacteremia persisted for 2-13 d in 11 (28.9%) patients; only 2 had apparent complications. Duration of treatment was 5-42 d (median 14 d); it was < or =15 d in 23/41 (56.1%) patients. Therapy was all intravenous (68%) or intravenous/oral (32%). Attributable mortality rate was 6% and relapse was encountered in 1/25 survivors (4%) with follow-up. These findings suggest that soft tissue-associated S. aureus bacteremia has a favorable prognosis with rapid clearance and infrequent metastatic infections. It may persist without an obvious complication. Oral therapy after a brief intravenous treatment appears safe and warrants further assessment.

Adult↗
PubMed2004

Suggestive evidence of association of C-159T functional polymorphism of the CD14 gene with atopic asthma in northern and northwestern Indian populations.

CD14 is a lipopolysaccharide receptor known to be an important modulator of Th1-Th2 response during early childhood. Genetic association studies of the CD14 gene with asthma and atopic disorders have shown positive as well as negative results in different ethnic populations. The aim of this study was to test for association of C-159T functional promoter polymorphism with atopic asthma and serum IgE levels in northern and northwestern Indian populations. DNA was assayed for the CD14 C-159T polymorphism in a case-control study involving atopic asthmatics (n=187) and healthy normal controls (n=227), and in a family-based association study of 106 trios. The case-control study showed an association at the genotypic (P=0.0146) as well as the allelic level (P=0.0048). Moreover, we observed a deviation of allelic transmission from random proportions (P=0.024) in the transmission disequilibrium test analysis. When we analyzed our results for serum total IgE levels, against this polymorphism, we observed a difference at the genotypic (P=0.0026) as well as at the allelic level (P=0.0016) in a case-control study, whereas no association in the quantitative transmission disequilibrium test analysis was obtained. These findings provide suggestive evidence of association of the CD14 gene locus with atopic asthma in northern and northwestern Indian populations.

Adult↗
PubMed2004

Frequency of reduced vancomycin susceptibility and heterogeneous subpopulation in persistent or recurrent methicillin-resistant Staphylococcus aureus bacteremia.

Vancomycin susceptibility was checked in isolates from initial and final blood samples obtained from 22 patients with persistent or recurrent methicillin-resistant Staphylococcus aureus bacteremia. The minimum inhibitory concentration of vancomycin was determined using Etest and found to have increased in 2 pairs of isolates, and results of screening in 4 mu g vancomycin and a modified population analysis profile suggested heteroresistance in 3 isolates (13.6%). Heteroresistance is not a common cause of persistent or recurrent bacteremia.

Anti-Bacterial Agents↗
PubMed2004

Sternal surgical-site infection following coronary artery bypass graft: prevalence, microbiology, and complications during a 42-month period.

OBJECTIVE: Surgical-site infection (SSI) is a serious and costly complication following coronary artery bypass graft (CABG). We analyzed surgical factors, microbiology, and complications at a 608-bed community teaching hospital to identify opportunities for prevention. METHODS: All patients undergoing CABG procedures from June 1997 through December 2000 were analyzed. Hospital records and postdischarge surveillance data were reviewed for demographics, surgical information, timing and classification of infection, microbiology, and bacteremic events. RESULTS: Of 3,443 patients undergoing CABG, sternal SSI developed in 122 (3.5%); 71 (58.2%) were classified as superficial SSI and 51 (41.8%) as deep SSI. Surgical antimicrobial prophylaxis was employed in all cases. On average, infection occurred 21.5 days (range, 4 to 315) after CABG. Most cases were diagnosed on readmission (59%); 20 cases (16%) were identified by postdischarge surveillance. Microbiological data were positive in 109 (89.3%), with a single pathogen implicated in most (86.2%). Gram-positive cocci were most frequently recovered (81%); gram-negative bacilli (17%), gram-positive bacilli (1%), and yeast (1%) were less common. Staphylococcus aureus was the most frequently isolated pathogen (49%). Bacteremia was noted in 22 instances (18%). It was significantly associated with deep SSI (P =. 002) and identified only in S. aureus cases. CONCLUSIONS: SSI complicated 3.5% of the procedures. S. aureus was implicated in most of the cases and was significantly associated with deep SSI. It was the only pathogen associated with secondary bacteremia. In addition to standard guidelines, targeted methods against S. aureus should help reduce the overall rate of SSI.

Aged↗
PubMed2003

Osteogenesis imperfecta with bleeding diathesis.

Osteogenesis imperfecta (OI) is a disorder of type 1 collagen synthesis with varied complications in form of brittle bones, hearing loss, dental, skin, and ocular changes. Osteogenesis imperfecta may have bleeding diathesis rarely due to defective vascular integrity for the same reason. Here we come across a rare case of Sillence type IB Osteogenesis imperfecta with bleeding in the form of repeated epistaxis and petechial rash, which seem to have a collagenous link.

Child↗
PubMed2003

Molecular analysis of Staphylococcus aureus blood isolates shows lack of polyclonal bacteremia.

Molecular analysis of the first blood culture from 41 patients with Staphylococcus aureus bacteremia and 20 bacteremia-associated catheter tip isolates revealed indistinguishable blood colonies in 39 patients (95.1%) and two related variants in two patients (4.9%). Polyclonal bacteremia was not observed in any patient, including four with genetic diversity in the catheter tip isolate.

Adolescent↗
PubMed2002

Cyanotic child--can it be methaemoglobinemia?

Methaemoglobinemia is a rare condition and can give surprise in emergency setup. We have encountered one such case in emergency recently that presented with both peripheral and central cyanosis without cardio-respiratory compromise. The patient was confirmed to be suffering from methaemoglobinemia due to antimalarials that he had received before coming to the hospital. Cyanosis due to methaemoglobinemia in our patient was precipitated by concomitant glucose 6-phosphate dehydrogenase (G6PD) deficiency. The patient was managed with conservative management and vitamin C administration.

Child↗
PubMed2002

Hepatic actinomycosis: an overview of salient features and outcome of therapy.

A 34-y-old African-American male developed Actinomyces liver abscess 8 months after appendectomy. Review of the English language literature revealed 56 additional cases of hepatic actinomycosis. Affected patients were typically immunocompetent, had a wide age range (4-86 y) and were predominantly male (70.2%). Infection was frequently (80.7%) cryptogenic, presenting with fever (83.3%), abdominal pain (74.5%) and weight loss (50.9%) over a 3.7 +/- 5.1 month period. The most common radiographic finding was a single hypodense mass/abscess (68.4%). Extension to surrounding tissues was evident in 19 cases (33.3%). Diagnosis was usually accomplished microscopically and culture was often (33.3%) negative. Infection was often (35.2%) mixed, usually with anaerobic bacteria. A surgical or percutaneous approach was diagnostic in 29/35 (82.9%) and 24/33 (72.7%) cases, respectively. The overall mortality rate was 8.8%; it was 10.7% with medical therapy alone and 4.0% using a combined medical/intervention approach (p = 0.6). In conclusion, hepatic actinomycosis is a rare subacute infection that may mimic neoplasm. It is usually cryptogenic, is more common among immunocompetent individuals and male subjects and is highly responsive to medical therapy.

Actinomyces↗
PubMed2002

Cryptococcus neoformans myositis without dissemination.

We report a case of isolated cryptococcal myositis involving the paraspinal muscle without evidence of disseminated disease in a patient with a large B-cell lymphoma diagnosed at the time of presentation. Biopsy of the muscle involved grew a pure culture of Cryptococcus neoformans and periodic acid-Schiff staining showed numerous budding yeast consistent with Cryptococcus spp. The patient responded to systemic antifungal therapy with complete resolution of his infection. We also present a review of 5 previously published cases of cryptococcal myositis.

Adult↗
PubMed2002

Clinical characteristics of necrotizing fasciitis caused by group G Streptococcus: case report and review of the literature.

A 52-y-old diabetic male developed severe necrotizing fasciitis due to group G Streptococcus. A review of the English language literature revealed 8 additional cases. The mean age of the total of 9 cases was 65.5 y (range: 49-80 y) and the majority (n = 5; 55.6%) had no comorbid conditions. The duration of symptoms prior to presentation was 1-5 d (mean +/- SD = 2.5 +/- 1.5 d). Presenting manifestations were swelling with redness (6/6 cases; 100%), severe pain (5/6 cases; 83.3%) and blister formation (3/6 cases; 50%); blisters developed eventually in 5/6 (88.3%) patients. Muscle involvement was noted in 2 patients (22.2%). Progression to toxic shock-like syndrome occurred in 3 cases (33.3%). The organism was isolated from the involved sites in all cases. Bacteremia was documented in 1/3 patients. Treatment included antibiotics (n = 9) and varying degrees of surgical debridement (n = 8). The mortality rate was 33.3%; all patients who died developed toxic shock-like syndrome. These findings illustrate that, similar to Streptococcus pyogenes-induced fasciitis, necrotizing fasciitis due to group G Streptococcus can be severe and life-threatening. Early diagnosis, immediate surgical debridement and antibiotic therapy are essential in order to improve the outcome.

Aged↗