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Biomedical subjects

A Tiwari

Publications and source records attributed to A Tiwari.

At least 37 records · Page 2Linked to original sources
PubMed2002

Acute compartment syndromes.

BACKGROUND: Acute compartment syndrome is both a limb- and life-threatening emergency that requires prompt treatment. To avoid a delay in diagnosis requires vigilance and, if necessary, intracompartmental pressure measurement. This review encompasses both limb and abdominal compartment syndrome, including aetiology, diagnosis, treatment and outcome. METHODS: A Pubmed and Cochrane database search was performed. Other articles were cross-referenced. RESULTS AND CONCLUSION: Diagnosis of limb compartment syndrome is based on clinical vigilance and repeated examination. Many techniques exist for tissue pressure measurement but they are indicated only in doubtful cases, the unconscious or obtunded patient, and children. However, monitoring of pressure has no harmful effect and may allow early fasciotomy, although the intracompartmental pressure threshold for such an undertaking is still unclear. Abdominal compartment syndrome requires measurement of intra-abdominal pressure because clinical diagnosis is difficult. Treatment is by abdominal decompression and secondary closure. Both types of compartment syndrome require prompt treatment to avoid significant sequelae.

Abdomen↗
PubMed2002

Compartment syndrome.

Explore the source record for details and available documents.

Arteriovenous Shunt, Surgical↗
PubMed2001

Trends in the utilization of androgen-deprivation therapy for patients with prostate carcinoma suggest an effect on mortality.

BACKGROUND: After a surge in the incidence of prostate carcinoma in the early 1990s, diminishing rates of mortality became apparent in 1993. This decrease in mortality is unlikely to be explained entirely by treatment with curative intent alone following screen-detected cases, because the time frame between detection and mortality remains relatively brief. METHODS: This study used incidence and initial treatment data from the Detroit area SEER registry between 1973 and 1998 in addition to mortality data covering the Metropolitan Detroit area obtained from the Michigan Department of Community Health. Data for Caucasian and African-American men were analyzed. The use of androgen-deprivation therapy, which evolved during the study period, was evaluated in conjunction with mortality and incidence trend data for consideration of etiologic contributions. RESULTS: The incidence of prostate carcinoma, as noted previously in national data, increased sharply in 1988, peaking in 1992 in Southeast Michigan, whereas mortality rates began to decrease in approximately 1993, with a sustained decrease to the latest recorded data in 1998. These trends were identical in Caucasians and African Americans. A sharp increase in the use of androgen-deprivation therapy began in 1990. This use of androgen-deprivation therapy is high and sustained for patients with early-stage disease, increases for several years, and then diminishes for patients with regional disease. The use also diminished through the 1990s for patients with late-stage disease, paralleling the decrease in the incidence rate for late-stage disease. CONCLUSIONS: The pattern of androgen-deprivation therapy usage was consistent with that for hormonal monotherapy and adjuvant and neoadjuvant therapy. These findings suggest that androgen-deprivation therapy may contribute, along with advances in diagnostic techniques and curative therapy with radiation or surgery, toward decreasing prostate carcinoma mortality rates in Southeast Michigan.

Adult↗
PubMed2001

Effect of pH on stability of anthrax lethal factor: correlation between denaturation and activity.

Anthrax is caused by Gram positive bacterium Bacillus anthracis. Pathogenesis is result of production of three protein components, protective antigen (PA), lethal factor (LF), and edema factor (EF). PA in combination with LF (lethal toxin) is lethal to animals, while PA in combination with EF (edema toxin), causes edema. PA, LF, and EF are very thermolabile. Differential scanning calorimetry (DSC) was used to unravel the energetics of LF denaturation as a function of pH ranging from 7.8 to 5.5. Transition temperature (T(m)) of LF was found to be approximately equal to 42 degrees C and onset of denaturation occurs at approximately equal to 30 degrees C. The ratio of calorimetric to van't Hoff's enthalpy was nearly equal to unity at pH 7.0, indicative of presence of single structural domain in LF at pH 7.0, unlike PA which has been structurally observed to consist of 4 domains. It was found by cytotoxicity studies using J774A.1 macrophage like cells that LF was most stable at pH approximately 6.5. This paper reports for the first time the denaturation of LF at different pH values at 37 degrees C and tries to establish a correlation between denaturation and loss of LF activity at different pH values.

Animals↗
PubMed2001

Cellular engineering of vascular bypass grafts: role of chemical coatings for enhancing endothelial cell attachment.

Surgical treatment of vascular disease has become common. The use of synthetic materials is limited to grafts larger than 5-6mm, because of the frequency of occlusion observed with small-diameter prosthetics. An alternative would be a hybrid or tissue-engineered graft with the surface coated with a monolayer of the patient's own cells. Currently, to be effective, high-density seeding regimens have to be undertaken. This is because endothelial cells (ECs) are washed off the graft lumen once exposed to physiological blood flow. EC attachment has been shown to be significantly improved by pre-coating with substances known to attach ECs selectively. The review examines the various types of coating and bonding technology used to date to enhance endothelial cell attachment onto the surface of prosthetic vascular bypass grafts.

Biocompatible Materials↗
PubMed2001

Acyl derivatives of demethylpenclomedine, an antitumor-active, non-neurotoxic metabolites of penclomedine.

PURPOSE: The purpose of this investigation was to compare the antitumor activities of a series of acyl derivatives of 4-demethylpenclomedine (DM-PEN), the major plasma metabolite of penclomedine (PEN) observed to be an active antitumor agent in vivo and non-neurotoxic in a rat model with that of DM-PEN. METHODS: Acyl derivatives were prepared from DM-PEN and evaluated in vivo against human MX-1 breast tumor xenografts implanted subcutaneously (s.c.) or intracerebrally (i.c.). Several derivatives were also evaluated against other human tumor xenografts and murine P388 leukemia cell lines. RESULTS: Several of the acyl derivatives were found to be superior to DM-PEN against MX-1, human ZR-75-1 breast tumor, human U251 CNS tumor and the P388 leukemia parent cell line and lines resistant to cyclophosphamide and carmustine. 4-Demethyl-4-methoxyacetylpenclomedine showed inferior activity to current clinical brain tumor drugs against a glioma cell line, superior activity to temozolomide and procarbazine against the derived mismatch repair-deficient cell line, and superior activity to cyclophosphamide and carmustine but inferior activity to temozolomide against two ependymoma cell lines, all of which were implanted s.c. CONCLUSION: Proposed mechanisms of activation and action of DM-PEN and the acyl derivatives support the potential clinical superiority of the acyl derivatives.

Animals↗
PubMed2001

Tissue engineering of vascular bypass grafts: role of endothelial cell extraction.

Surgical treatment of vascular disease has become common. The use of synthetic materials is limited to grafts larger than 5-6 mm, because of the frequency of occlusion observed with small-diameter prosthetics. An alternative would be a hybrid or tissue-engineered graft with the surface coated with a monolayer of the patients' own endothelial cells. This review examines the various techniques and technologies used to date in order to extract endothelial cells for such graft engineering.

Biomedical Engineering↗
PubMed2001

Ren and Yuan: a cultural interpretation of Chinese women's responses to battering.

The purpose of the study was to examine women's responses to battering within the context of Chinese culture. The stories of 11 Chinese women living in Hong Kong formed the basis of the inquiry. Analysis of the women's accounts revealed Chinese values in their responses to battering: they adopted ren, or endurance, as a coping mechanism and used Yuan, or predestination, as an explanation for their failed relationship. The resilience and resourcefulness of the women are clearly demonstrated in the strategies they employed to cope with the abuse. Their responses to battering were purposeful and varied according to the status of their relationship.

Adaptation, Psychological↗
PubMed2000

Synthesis and evaluation of several new (2-chloroethyl)nitrosocarbamates as potential anticancer agents.

Seven new (2-chloroethyl)nitrosocarbamates have been synthesized as potential anticancer alkylating agents. These compounds were designed with carrier moieties that would either act as prodrugs or confer water solubility. All compounds were screened in an in vitro panel of five human tumor cell lines: CAKI-1 (renal), DLD-1 (colon), NCI-H23 (lung), SK-MEL-28 (melanoma), and SNB-7 (CNS). Several agents showed good activity with IC(50) values in the range of 1-10 microg/mL against at least two of the cell lines. One compound, carbamic acid, (2-chloroethyl)nitroso-4-acetoxybenzyl ester (3), was selected for further study in vivo against intraperitoneally implanted P388 murine leukemia. In addition to the aforementioned compound, both carbamic acid, (2-chloroethyl)nitroso-4-nitrobenzyl ester (9) and carbamic acid, (2-chloroethyl)nitroso-2,3,4, 6-tetra-O-acetyl-1-alpha,beta-D-glucopyranose ester (24) were evaluated against subcutaneously implanted M5076 murine sarcoma in mice. None of these compounds were active in vivo.

Animals↗
PubMed2000

Necrotizing fasciitis: a rare complication of total hip replacement.

Necrotizing fasciitis is a rare, but life-threatening emergency. We report a case history of necrotizing fasciitis in a previously healthy woman. A review of the literature suggests that this is the first report of necrotizing fasciitis complicating total hip replacement surgery.

Aged↗
PubMed2000

Hydroxamate siderophores of Histoplasma capsulatum.

The zoopathogenic fungus Histoplasma capsulatum, like other eukaryotic aerobic microorganisms, requires iron for growth. Under conditions of low iron availability, the fungus secretes hydroxamates that function as siderophores (iron chelators). The experiments to be reported were designed to gather further information on the hydroxamate siderophores of H. capsulatum. The fungus was grown in a synthetic medium deferrated with the cationic exchange resin Chelex 100. Siderophores were detected after 4 days of incubation at 37 degrees C in media containing 0.3 to 1.0 microM iron. The secretion was suppressed by 10 microM iron. The hydroxamates were purified by reverse-phase and size-exclusion chromatography. On the basis of ions observed during electrospray mass spectroscopy, five hydroxamate siderophores were tentatively identified: dimerum acid, acetyl dimerum acid, coprogen B, methyl coprogen B, and fusarinine (monomeric). A polyclonal antibody to dimerum acid was generated. This reagent cross-reacted with coprogen B and fusarinine. Thus, the antibody detects hydroxamates in all three families of siderophores excreted by H. capsulatum.

Antibodies↗
PubMed1998

The OxyS regulatory RNA represses rpoS translation and binds the Hfq (HF-I) protein.

The OxyS regulatory RNA integrates the adaptive response to hydrogen peroxide with other cellular stress responses and protects against DNA damage. Among the OxyS targets is the rpoS-encoded sigma(s) subunit of RNA polymerase. Sigma(s) is a central regulator of genes induced by osmotic stress, starvation and entry into stationary phase. We examined the mechanism whereby OxyS represses rpoS expression and found that the OxyS RNA inhibits translation of the rpoS message. This repression is dependent on the hfq-encoded RNA-binding protein (also denoted host factor I, HF-I). Co-immunoprecipitation and gel mobility shift experiments revealed that the OxyS RNA binds Hfq, suggesting that OxyS represses rpoS translation by altering Hfq activity.

Bacterial Proteins↗