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Biomedical subjects

M Kumar

Publications and source records attributed to M Kumar.

At least 73 records · Page 4Linked to original sources
PubMed1998

Acute cholecystitis in AIDS patients: correlation of Tc-99m hepatobiliary scintigraphy with histopathologic laboratory findings and CD4 counts.

BACKGROUND: AIDS patients are susceptible to opportunistic gastrointestinal infections including ascending cholangitis and cholecystitis, especially if CD4 count is < 200. Incidence of acalculous cholecystitis has not been reported previously. PURPOSE: We aim to evaluate the incidence of acalculous cholecystitis in AIDS patients and to identify causative organisms and mortality rate following cholecystectomy. MATERIALS AND METHODS: We reviewed the files of 46 patients in order to meet the objectives of this study. RESULTS: CD4 counts were < 200 in 31 patients and > 200 in 15 patients. HIDA imaging was performed in 31 patients; in 8, the CD4 count was > 200 and all had calculous cholecystitis. The gallbladder was visualized in 3 patients for a sensitivity of 63% and no organisms were found in the gallbladder specimens. In 23 patients, the CD4 count was < 200; the gallbladder was visualized in 5 patients for a HIDA sensitivity of 78%; 16 (52%) had acalculous cholecystitis; and 15 had calculous cholecystitis. In acalculous cholecystitis, Cryptosporidium was found in six cases, cytomegalovirus (CMV) in six cases, and fungus, yeast, tuberculosis, and mycobacterium avium intracellular each in one case. The thirty day mortality rate was 18%; 5 of 28 who underwent open cholecystectomy died within 30 days, 4 of them with a CD4 count < 200. There was no mortality in the 26 patients who underwent laparoscopic cholecystectomy. CONCLUSION AND RECOMMENDATIONS: (1) Because of the high incidence of 52% of acalculous cholecystitis in AIDS patients with a CD4 count < 200, we recommend using intravenous cholecystokinin if the gallbladder is visualized on hepatobiliary scintigraphy in order to determine gallbladder ejection fraction and exclude acalculous cholecystitis. (2) Laparoscopic rather than open cholecystectomy should be the surgical procedure of choice in AIDS patients especially if the CD4 count is < 200.

AIDS-Related Opportunistic Infections↗
PubMed1998

SPECT brain perfusion abnormalities in mild or moderate traumatic brain injury.

The purpose of this atlas is to present a review of the literature showing the advantages of SPECT brain perfusion imaging (BPI) in mild or moderate traumatic brain injury (TBI) over other morphologic imaging modalities such as x-ray CT or MRI. The authors also present the technical recommendations for SPECT brain perfusion currently practiced at their center. For the radiopharmaceutical of choice, a comparison between early and delayed images using Tc-99m HMPAO and Tc-99m ECD showed that Tc-99m HMPAO is more stable in the brain with no washout over time. Therefore, the authors feel that Tc-99m HMPAO is preferable to Tc-99m ECD. Recommendations regarding standardizing intravenous injection, the acquisition, processing parameters, and interpretation of scans using a ten grade color scale, and use of the cerebellum as the reference organ are presented. SPECT images of 228 patients (age range, 11 to 88; mean, 40.8 years) with mild or moderate TBI and no significant medical history that interfered with the results of the SPECT BP were reviewed. The etiology of the trauma was in the following order of frequency: motor vehicle accidents (45%) followed by blow to the head (36%) and a fall (19%). Frequency of the symptoms was headache (60.9%), memory problems (27.6%), dizziness (26.7%), and sleep disorders (8.7%). Comparison between patients imaged early (<3 months) versus those imaged delayed (>3 months) from the time of the accident, showed that early imaging detected more lesions (4.2 abnormal lesions per study compared to 2.7 in those imaged more than 3 months after the accident). Of 41 patients who had mild traumatic injury without loss of consciousness and had normal CT, 28 studies were abnormal. Focal areas of hypoperfusion were seen in 77% (176 patients, 612 lesions) of the group of 228 patients. The sites of abnormalities were in the following order: basal ganglia and thalami, 55.2%, frontal lobes, 23.8%, temporal lobes, 13%, parietal, 3.7%, insular and occipital lobes together, 4.6%.

Adolescent↗
PubMed1998

No difference exists in the alteration of circadian rhythm between patients with and without intensive care unit psychosis.

OBJECTIVE: To determine if a difference exists in the circadian rhythm entrainment between patients with and without intensive care unit (ICU) psychosis. DESIGN: Retrospective chart reviews from 149 consecutive patients admitted to our ICU during the period of January 1993 to August 1993. Twelve patients with a history of mental illness or alcohol or substance abuse were excluded from the study. SETTING: A 20-bed surgical ICU at a large teaching hospital. PATIENTS: Patients who remained in the ICU for a minimum of 2 days after undergoing thoracic or vascular operations. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Hourly temperature and urine output were ascertained from the patient records. The time of temperature and urine output nadir was used as a marker of circadian rhythm. Of the 137 patients included in the study, 17 (12.4%) developed ICU psychosis as defined by standard criteria. The time of temperature nadir was randomly distributed around the clock for each group. Cosinar rhythmometry analysis of temperature data showed a lack of circadian rhythm entrainment in most patients up to the third postoperative day. No statistically significant difference exists in the deviation of such impairment between the groups. CONCLUSION: Either patients who develop ICU psychosis have an increased sensitivity to an alteration of their circadian rhythm, or ICU psychosis develops independent of circadian rhythm abnormalities.

Adaptation, Physiological↗
PubMed1998

Comparison of SPET brain perfusion and 18F-FDG brain metabolism in patients with chronic fatigue syndrome.

Chronic fatigue syndrome is a clinically defined condition of uncertain aetiology. We compared 99Tcm-HMPAO single photon emission tomography (SPET) brain perfusion with dual-head 18F-FDG brain metabolism in patients with chronic fatigue syndrome. Eighteen patients (14 females, 4 males), who fulfilled the diagnostic criteria of the Centers for Disease Control for chronic fatigue syndrome, were investigated. Thirteen patients had abnormal SPET brain perfusion scans and five had normal scans. Fifteen patients had normal glucose brain metabolism scans and three had abnormal scans. We conclude that, in chronic fatigue syndrome patients, there is discordance between SPET brain perfusion and 18F-FDG brain uptake. It is possible to have brain perfusion abnormalities without corresponding changes in glucose uptake.

Brain↗
PubMed1998

Hematopoietic growth factors for the treatment of aplastic anemia.

The use of hematopoietic growth factors, although well established for the management of chemotherapy-induced neutropenia, remains controversial for the treatment of aplastic anemia and inherited bone marrow failure syndromes. The most commonly used factors are granulocyte colony-stimulating factor, granulocyte macrophage colony-stimulating factor, and erythropoietin. Newer growth factors such as stem cell factor, thrombopoietin, Flt3 ligand, and interleukins have shown promising results in the laboratory, and some have been used in clinical trials. This article reviews the clinical use of old and new hematopoietic growth factors in acquired and inherited bone marrow failure, and discusses emerging concerns about long term toxicity of these factors.

Anemia, Aplastic↗
PubMed1998

A bereavement support group intervention is longitudinally associated with salutary effects on the CD4 cell count and number of physician visits.

A randomized, controlled, clinical trial was conducted to examine the impact of a semistructured, 10-week, once weekly, 90-min/session bereavement support group intervention on immunological, neuroendocrine, and clinical health status in human immunodeficiency virus type 1-seropositive (HIV-1+) and HIV-1-seronegative (HIV-1-) homosexual men, compared to a standard of care control condition. A total of 119 homosexual men (74 HIV-1+ and 45 HIV-1-) were assessed at baseline, 10 weeks, and 6 months follow-up. At the 6-month follow-up assessment, the intervention groups exhibited significant beneficial effects compared to controls on changes in CD4 cell, total T-lymphocyte, and total lymphocyte counts, when baseline levels, antiretroviral medication use, CDC stage of disease, and other potentially confounding factors were accounted for. There was no statistically significant effect on the CD4/CD8 ratio or on the CD8 cell count. The effect on CD4 cell count was associated with group attendance and with changes in plasma cortisol level. Plasma cortisol levels decreased significantly among intervention subjects, compared to controls. A significantly reduced number of health care visits over the 6-month follow-up period among the intervention subjects supported the clinical relevance of the immunological changes observed for both HIV-1+ and HIV-1- individuals. These results indicate that behavioral interventions may have salutary immunological and clinical health effects following bereavement among HIV-1-infected individuals. The effect in HIV-1- individuals suggests that this bereavement support group intervention might have similar salutary effects in the general population. Potential effects of such interventions on clinical HIV disease progression are of interest and should be studied.

Adult↗
PubMed1998

Antisense RNA: function and fate of duplex RNA in cells of higher eukaryotes.

There is ample evidence that cells of higher eukaryotes express double-stranded RNA molecules (dsRNAs) either naturally or as the result of viral infection or aberrant, bidirectional transcriptional readthrough. These duplex molecules can exist in either the cytoplasmic or nuclear compartments. Cells have evolved distinct ways of responding to dsRNAs, depending on the nature and location of the duplexes. Since dsRNA molecules are not thought to exist naturally within the cytoplasm, dsRNA in this compartment is most often associated with viral infections. Cells have evolved defensive strategies against such molecules, primarily involving the interferon response pathway. Nuclear dsRNA, however, does not induce interferons and may play an important posttranscriptional regulatory role. Nuclear dsRNA appears to be the substrate for enzymes which deaminate adenosine residues to inosine residues within the polynucleotide structure, resulting in partial or full unwinding. Extensively modified RNAs are either rapidly degraded or retained within the nucleus, whereas transcripts with few modifications may be transported to the cytoplasm, where they serve to produce altered proteins. This review summarizes our current knowledge about the function and fate of dsRNA in cells of higher eukaryotes and its potential manipulation as a research and therapeutic tool.

Animals↗
PubMed1998

Cerebral perfusion imaging in asymptomatic carotid artery occlusion following gun shot.

Recognition of brain injury in asymptomatic carotid artery injuries with conventional methods can be difficult. We present a case of angiographically proven asymptomatic left internal carotid artery occlusion with normal CT after a gunshot wound. The SPECT brain perfusion imaging showed mild generalized supratentorial hypoperfusion of the bilateral cerebral cortices on the left side and severe left temporal lobe hypoperfusion.

Adult↗
PubMed1998

An alternative approach to bandage contact lenses.

PURPOSE: Therapeutic bandage contact lenses have been used in the management of a variety of corneal and anterior segment disorders. However, clinical experience with the therapeutic use of disposable contact lenses is limited. The present study was designed to evaluate the efficacy of disposable contact lenses as bandage lenses in anterior segment disorders. METHODS: We fit 45 patients who had various corneal and anterior segment disorders with disposable contact lenses (42% etafilcon A and 58% water content). We used this lens as a healing and surgical adjunct and for structural support and symptomatic relief. Patients were followed for a minimum period of 3 months. Therapeutic efficacy and complications were evaluated. RESULTS: Eighty-two percent of patients were fit successfully. Ninety-one percent of the successfully fit patients were therapeutic successes. Disposable lenses were found to be very useful in the management of epithelial abnormalities and as surgical adjuncts. Dry eye was the most frequent cause of contact lens associated therapeutic failure. Complications included contact lens deposits, lens loss, and corneal neovascularization. CONCLUSIONS: The use of disposable lenses was most effective in conditions requiring short-term lens use where one to two lens applications were sufficient to allow healing, making disposable lenses a very convenient and cost-effective alternative to conventional therapeutic bandage contact lenses. For reasons of cost, disposable lenses were not a viable alternative in conditions requiring therapeutic lens use for long periods of time.

Adult↗
PubMed1998

Infective and traumatic aneurysms.

Traumatic intracranial aneurysms are rare lesions but should be considered in penetrating head injury, particularly in cases of low-velocity gunshot wounds or stab wounds to the head. Because most of these aneurysms are false aneurysms, treatment may require excision or trapping procedures.

Anti-Bacterial Agents↗
PubMed1997

Mechanism of carbon monoxide oxidation by the carbon monoxide dehydrogenase/acetyl-CoA synthase from Clostridium thermoaceticum: kinetic characterization of the intermediates.

Carbon monoxide dehydrogenase/acetyl-CoA synthase (CODH/ACS) from Clostridium thermoaceticum catalyzes (i) the synthesis of acetyl-CoA from a methylated corrinoid protein, CO, and coenzyme A and (ii) the oxidation of CO to CO2. CO oxidation occurs at a Ni- and FeS-containing center known as cluster C. Electrons are transferred from cluster C to a separate metal center, cluster B, to external acceptors like ferredoxin. In the work described here, we performed reductive titrations of CODH/ACS with CO and sodium dithionite and monitored the reaction by electron paramagnetic resonance (EPR) spectroscopy. We also performed pre-steady-state kinetic studies by rapid freeze-quench EPR spectroscopy (FQ-EPR) and stopped-flow kinetics. Redox titrations of CODH/ACS revealed the existence of a UV-visible and EPR-silent electron acceptor denoted center S that does not appear to be associated with any of the other metal centers in the protein. Our results support the previous proposals [Anderson, M. E., & Lindahl, P. A. (1994) Biochemistry 33, 8702-8711; Anderson, M. E., & Lindahl, P. A. (1996) Biochemistry 35, 8371-8380] that the Cred2 form of cluster C is two electrons more reduced than the Cred1 form. The combined results from titrations and pre-steady-state studies were used to formulate a mechanism for CO oxidation, composed of the following steps: (i) CO binding to the [Cred1,Box, Xox] state to yield a Cred1-CO complex; (ii) two-electron reduction of Cred1 to Cred2 concerted with CO2 release; (iii) binding of a second CO molecule to the [Cred2,Box,Xox] state to form a Cred2-CO complex; (iv) electron transfer from Cred2-CO to cluster B to form [Cred2,Bred,Xred] with concerted release of the second CO2. Step iii competes with internal electron transfer from Cred2 to Box and Xox. At high CO concentrations, step iii is favored, whereas at low concentrations, only one CO molecule per turnover binds and undergoes oxidation. Closure of the catalytic cycle involves electron transfer from reduced enzyme to an electron acceptor protein, like ferredoxin. Xox is a yet-uncharacterized electron acceptor that may be an intermediate in the reduction of center S. The Cred2 state appears to be the predominant state of cluster C during steady-state turnover. The rate-determining step for the first half-reaction is step iv, while during steady-state turnover, it appears to be electron transfer to external electron acceptors.

Aldehyde Oxidoreductases↗