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Biomedical subjects

A K Haque

Publications and source records attributed to A K Haque.

At least 37 records · Page 2Linked to original sources
PubMed1995

Massive hepatic steatosis and lactic acidosis in a patient with AIDS who was receiving zidovudine.

Massive steatosis has recently been described among a few human immunodeficiency virus-seropositive patients who were receiving antiretroviral therapy. Although clinical and light-microscopic pathological findings were carefully described, no ultrastructural studies of the liver were performed in these cases. We report the light-microscopic and ultrastructural findings at autopsy of a 35-year-old woman with AIDS who developed severe lactic acidosis and hepatic failure. The patient had been receiving standard doses of zidovudine for 5 months when she was hospitalized because of the rapid onset of abdominal pain, nausea, and vomiting. The most significant findings at autopsy were massive hepatomegaly and steatosis. Ultrastructural examination of the liver and skeletal muscle showed slightly enlarged mitochondria in the liver but no mitochondrial changes in the skeletal muscle. The pathogenesis of mitochondrial toxicity associated with antiviral therapies is briefly discussed.

Acidosis, Lactic↗
PubMed1995

Comparison of pulmonary neutrophils in the adult and neonatal rat after hyperoxia.

The mechanisms of the increased tolerance to hyperoxia of neonatal animals of many species is incompletely understood. To investigate the etiology of this difference we compared neutrophil entry into the lungs of neonatal and adult rats after hyperoxic exposure. Adult rats were studied after exposure to > or = 98% O2 for 60 h and neonatal rats after 3 and 7 d. Neonatal survival was prolonged compared with that reported for adult rats (77% after 7 d of exposure). In adult rats, there were significant increases in pulmonary neutrophils after 60 h of O2 exposure. In neonatal rats, these changes were not evident after 72 h of exposure, but pulmonary neutrophils increased after 7 d of hyperoxia. Before mortality, pulmonary neutrophils were distributed differently in the age groups. After 7 d of O2 exposure in the neonates, total neutrophil counts in lung tissue (21.92 +/- 7.29 per cm2 grid) and lung myeloperoxidase (0.085 +/- 0.02 U/mg protein) remained significantly lower than in adults after 60 h of O2 exposure (41.44 +/- 9.08 per cm2 grid and 0.411 +/- 0.085 U/mg protein, respectively). However, in histologic specimens, O2-exposed neonates had higher percentages of neutrophils free in the alveolar air space than did adults, corresponding to a trend toward higher neutrophil counts in bronchoalveolar lavage fluid in the neonates. It appears that, in addition to delay in neutrophil influx into the lung, neonatal rats have lowered retention of neutrophils to the alveolar tissue.

Aging↗
PubMed1994

Oxygen-induced lung injury in the guinea pig proceeds through CD18-independent mechanisms.

The pathogenesis of pulmonary oxygen toxicity is postulated to be related in part to neutrophil-mediated injury. This study examined the effect of a monoclonal antibody directed against the CD11a,b,c/CD18 glycoprotein complex (beta 2 leukocyte integrins) on oxygen-induced lung injury. M8, a monoclonal antibody that binds to the beta chain of the guinea pig leukocyte integrins that facilitate neutrophil adherence to vascular endothelium, was injected into adult guinea pigs prior to and during exposure to > 98% oxygen. Control oxygen-exposed animals were injected with a noninhibitory antibody to the CD18 complex or with saline. Survival in oxygen was similar for animals treated with M8 when compared with those treated with saline (102 versus 105 h, respectively, NS). Pulmonary edema as assessed by protein in the supernatant of bronchoalveolar lavage fluid (BALF) was higher in the three groups of oxygen-exposed animals than in the air-exposed groups (p < 0.01), but it did not differ between the M8 antibody treatment group and the other oxygen-exposed groups. M8 antibody treatment did not decrease hyperoxia-induced neutrophil accumulation into the lung as assessed by myeloperoxidase activity (MPO) in lung homogenates or by neutrophil counts in histologic specimens. M8 antibody also did not decrease neutrophil counts or MPO in alveolar lavage fluid, both of which were significantly elevated in all oxygen-exposed groups. These results suggest that hyperoxia-induced neutrophil migration into the lung and acute lung injury occurs by CD18-independent processes in the guinea pig model of pulmonary oxygen toxicity.

Animals↗
PubMed1994

Pathogenesis of human strongyloidiasis: autopsy and quantitative parasitological analysis.

The distribution of pathologic lesions and the parasite burden of major organs were studied in seven patients with disseminated strongyloidiasis who were autopsied at the University of Texas Medical Branch (Galveston, TX). All patients were immunosuppressed and had additional bacterial, viral, and fungal infections; six patients had received cortisone therapy and one patient had AIDS. High Strongyloides burdens were noted in untreated patients or in those with a short period of treatment. The proximal small intestine and the lungs showed the heaviest parasite burden, with large numbers of filariform larvae found in both locations. The lungs showed persistence of larvae in all patients, in the absence of intestinal or extraintestinal infection; this suggests that the respiratory cycle may be more resistant to therapy than the intestinal cycle. In the intestines, filariform larvae were seen at all levels, but higher burdens were seen in the upper as compared to lower small intestine, and larvae were more concentrated in the proximal jejunum than in the duodenum. Autoinfection (i.e., filariform larval penetration) occurred more prominently in the distal small and proximal large intestine than in the distal colon. Most filariform larvae were found in the intestinal lymphatics and were highly concentrated in mesenteric and retroperitoneal lymph nodes; conversely, larvae were not found in the spleen and were found in very low density in the liver. These findings, in concert, suggest that during autoinfection in humans, the Stronglyloides larvae transverse lymphatics to the thoracic duct, then pursue a lymphohematogenous dissemination to the lungs where they penetrate the air spaces and ascend through the airways to reach the gut.

AIDS-Related Opportunistic Infections↗
PubMed1993

Total parenteral nutrition-associated alterations in hepatobiliary function and histology in rats: is light exposure a clue?

Light exposure of amino acids, especially in the presence of photosensitizers such as riboflavin, has been shown to result in photoproducts that are toxic both in vivo and in vitro. Provision of photooxidized single amino acids has been shown to result in hepatic dysfunction in both gerbils and rats. However, studies of the effects of light exposure of complete nutrient mixtures (glucose-amino acid-vitamins) on hepatobiliary responses are limited. These are important because, in clinical practice, total parenteral nutrition (TPN) solutions are continually exposed to light and because hepatic dysfunction is the most common metabolic aberration associated with TPN. Studies were conducted to compare the effects of TPN that had been exposed to light (+L) or protected from light (-L) on hepatobiliary function of rats. TPN solutions were either exposed to light or protected from light for 24 h and then infused into rats for 10 d. Data for enterally fed rats are also shown for comparison with parenterally fed animals. +L animals lost more weight and had lower bile flow, higher taurocholate output in bile, higher biliary osmolarity, and higher inorganic phosphate in bile. Hepatic histology demonstrated scattered foci of necrosis in eight of the eight +L animals and in only one of eight -L animals. These data demonstrate that protection of TPN solutions from light minimizes TPN-associated alterations in hepatobiliary function and histology. These histologic changes observed in the +L animals are in contrast to previous reports of TPN-induced histologic changes, suggesting a different mechanism. Our observations suggest that consideration be given to the implications of exposing TPN solutions to light.

Animals↗
PubMed1993

Proliferation of dendritic cells in the bronchioles of sudden infant death syndrome victims.

Sudden Infant Death Syndrome (SIDS) victims have significantly thickened bronchiolar walls with increased mononuclear cells in the adventitia. An immunohistochemical study was performed on 25 SIDS and 18 aged-matched control infants to characterize these cells. The panel of antibodies included alpha-1-antitrypsin, lysozyme, actin, vimentin, Leu M1, NSE, S-100, Leu 6, bombesin, serotonin, anti-substance P, vasoactive intestinal peptide, MAC 387, and Factor XIIIa. The bronchiolar cells stained with S-100 antibody and demonstrated slender processes similar to dendritic cells, such as Langerhans' cells, and interdigitating reticulum cells, present in normal tissues as well as in certain tumors and inflammatory diseases. Manual counting of the S-100 positive cells and fibers revealed both of these to be significantly increased in SIDS infants as compared to age-matched control infants. Morphologically, the bronchiolar dendritic cells closely resembled Langerhans' cells and therefore may have similar immunologic functions, such as antigen presentation and viral and neoantigen immunosurveillance. We hypothesize that the proliferation of these dendritic cells in SIDS victims is a result of exposure to environmental antigens, resulting in a thickening of the bronchiolar walls, narrowing of the lumen, and reduction in airflow, thus causing a chronic or persistent hypoxia.

Bronchi↗
PubMed1993

Heparin improves oxygenation and minimizes barotrauma after severe smoke inhalation in an ovine model.

Inhalation injury is one of the main causes of mortality in burn victims. The tracheobronchial epithelium sloughs and combines with a protein rich exudate to form casts of the airways that can lead to obstruction. We studied the effects of a continuous infusion of heparin on the acute pulmonary injury that occurs after smoke inhalation injury in sheep. Twelve ewes with vascular catheters received a standardized smoke inhalation injury and mechanical ventilation according to protocol for 72 hours. The heparin group (n = 6) received a 400 unit per kilogram bolus of heparin followed by a continuous infusion to maintain the activated clotting time between 250 to 300 seconds. The control group (n = 6) received a saline solution vehicle. Hemodynamics, blood gases and plasma samples for conjugated dienes were taken every six hours. At necropsy, pulmonary tissue was collected for histologic findings, polymorphonuclear neutrophil leukosequestration, wet-to-dry weight ratios and conjugated dienes. PaO2 to FIO2 ratios were improved in the heparin group compared with the control group at 12 to 72 hours after injury, and peak airway pressures were higher in the control group compared with the heparin group. Positive end expiratory pressure requirements were higher in the control group compared with the heparin group. There were significantly fewer airway tracheobronchial casts as determined by our tracheobronchial casts scoring system (2.4 +/- 0.4 versus 0.67 +/- 0.21) and confirmed by histologic examination. Pulmonary blood-free wet-to-dry weight ratios were higher in the control group compared with the heparin group (6.4 +/- 0.5 versus 5.2 +/- 0.1; p < 0.05). There were no differences in pulmonary tissue or plasma conjugated dienes; likewise, pulmonary leukosequestration was unaffected by heparin. Heparin decreases tracheobronchial cast formation, improves oxygenation, minimizes barotrauma and reduces pulmonary edema in an ovine model of severe smoke inhalation injury. Heparin does not reduce oxygen free radical activity after smoke inhalation injury.

Analysis of Variance↗
PubMed1992

Pulmonary toxicity of acrylonitrile: covalent interaction and effect on replicative and unscheduled DNA synthesis in the lung.

Acrylonitrile (VCN)-induced lung toxicity was studied following a single oral dose (46.5 mg/kg). The mechanism of toxic injury was investigated by assessing the covalent interaction of [2,3-14C]VCN with pulmonary DNA. The effect of the same dose on replicative DNA synthesis and repair in the lungs of treated rats was also investigated. Histologic examination revealed that lungs of VCN-treated animals showed moderate to marked hyperplasia of the Clara cells lining the bronchioles. [14C]Lung tissue uptake was extremely fast, having a maximum at 0.5 h after treatment (150 DPM tissue). Radioactivity in lung tissue declined gradually as a function of time, but was still detected at 72 h after treatment (59 DPM/mg tissue). Covalent binding of [14C]VCN-derived radioactivity to pulmonary DNA was time-dependent, reaching a maximum at 12 h following treatment (61 DPM/mg DNA) and was still detected at 72 h (27 DPM/mg DNA) indicating the incomplete removal of radioactivity covalently bound to DNA. Replicative DNA synthesis in lung tissue was significantly decreased at all time points studied (59, 55 and 72% of control at 0.5, 6 and 24 h, respectively). The DNA repair in the lung was increased by 2-fold at 0.5 h and 1.6-fold at 6 h following VCN oral treatment. The histologic and biochemical results presented in this study provide evidence for the acute genetic toxicity of VCN (and/or its metabolites) in lung tissue following a single oral dose of VCN.

Acrylonitrile↗
PubMed1992

Glutathione S-transferases of human lung: characterization and evaluation of the protective role of the alpha-class isozymes against lipid peroxidation.

Glutathione S-transferase (GST) isozymes of human lung have been purified, characterized, quantitated, and, based on their structural and immunological profiles, identified with their respective classes. The tau-, mu-, and alpha-class GSTs represented 94, 3, and 3% activities of total human lung GSTs toward CDNB, respectively, and 60, 10, and 30% of total GST protein, respectively. Both the mu- and the alpha-class GSTs of human lung exhibited heterogeneity. The two mu-class GSTs of human lung had pI values of 6.5 and 6.25 and were differentially expressed in humans. Significant differences were seen between the kinetic properties of these two isozymes and also between the lung and liver mu-class GSTs. The alpha-class GST isozymes of lung resolved into three peaks during isoelectric focusing corresponding to pI values of 9.2, 8.95, and 8.8. All three alpha-class GSTs isozymes had blocked N-termini and were immunologically similar to human liver alpha-class GSTs. Peptide fingerprints generated by SV-8 protease digestion and CNBr cleavage indicated minor structural differences between the liver and the lung alpha-class GSTs. The three alpha-class GSTs of lung expressed glutathione peroxidase activities toward the hydroperoxides of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylglycerol, with Km values in the range of 22 to 87 microM and Vmax values in the range of 67-120 mol/mol/min, indicating the involvement of the alpha-class GSTs in the protection mechanisms against peroxidation. All three classes of lung GSTs expressed activities toward leukotriene A4 methyl ester and epoxy stearic acid but the mu-class GSTs had relatively higher activities toward these substrates.

Blotting, Western↗
PubMed1992

Asbestos in organs and placenta of five stillborn infants suggests transplacental transfer.

Digests of lungs, liver, and placenta from five stillborn infants of 22 to 38 weeks gestational age were examined for asbestos and other fibers using light and electron microscopy, energy dispersive X-ray analysis, and selected area diffraction analysis. Uncoated chrysotile asbestos fibers were found in the digests of at least one of the three tissues examined from each stillborn infant. The asbestos fiber burdens ranged from 71,000 to 357,000 fibers/g wet tissue. Most of the fibers were small, with the mean length ranging from 0.83 to 2.53 microns. While appreciable numbers of uncoated chrysotile fibers were present, no coated asbestos fibers were found in any of the stillborns. Both coated and uncoated nonasbestos fibers were found in at least one of the tissue digests of all five stillborns. The uncoated nonasbestos fibers were characterized as aluminum silicates, diatomaceous earth fragments, or other fibers. The coated nonasbestos fibers or ferruginous bodies were consistent with being formed on diatomaceous earth fragments, black carbon cores, or sheet silicate cores. Since the placenta is the only route of communication between the fetus and the outside environment, our findings strongly suggest a transplacental transfer of asbestos and other fibers in humans.

Asbestos↗
PubMed1992

Immediate positive pressure ventilation with positive end-expiratory pressure (PEEP) improves survival in ovine smoke inhalation injury.

BACKGROUND: The purpose of this study was to compare the effects of immediate initiation of positive pressure ventilation (PPV) with positive end-expiratory pressure (PEEP) versus the initiation of PPV with PEEP only after hypoxemia ensued following severe smoke inhalation injury. METHODS: We prospectively evaluated chronically instrumented adult sheep treated with immediate versus delayed PPV with PEEP and compared oxygen requirements, hemodynamics, pleural fluid formation, postinjury survival, and tracheobronchial pathologic processes among groups. The immediate group (group I; smoke, n = 6; sham, n = 2) underwent tracheostomy and bilateral chest tube placement before they received inhalation injury. They were then immediately placed on PPV with PEEP (12 cm H2O). The animals in the delayed group (group D) (n = 6) were placed on PPV with PEEP when arterial hypoxemia (PaO2 < 80 mm Hg [11.2 kPa] on 0.4 FIO2) or respiratory distress developed. RESULTS: Groups were matched for smoke exposure and peak carboxyhemoglobin. Both groups developed a characteristic decrease in PaO2/FIO2 ratio. Initiation of PPV + PEEP improved PaO2 in the delayed group (69 +/- 7 to 126 +/- 21 mm Hg [9.2 +/- 0.9 to 16.7 +/- 2.8 kPa]). Pleural fluid output was greater in the immediate group compared with the delayed group (1559 +/- 415 vs. 426 +/- 236 mL). At 96 hours after injury five of six animals in the delayed group had died. In contrast, six of six animals in the immediate smoke group survived 96 hours (p < 0.05 versus delayed group). The immediate group had fewer and less extensive tracheobronchial casts at necropsy. CONCLUSIONS: Immediate PPV + PEEP did not prevent the development of hypoxia and was associated with increased pleural fluid formation. Death within 96 hours in the delayed group was the result of respiratory failure aggravated by bronchial cast formation despite vigorous pulmonary toilet. Early positive pressure ventilation with PEEP, preferably initiated immediately after the inhalation insult, significantly increases short-term survival and is associated with decreased tracheobronchial cast formation in this ovine model of severe smoke inhalation injury.

Animals↗
PubMed1992

Pathology of common pulmonary fungal infections.

The incidence of fungal pneumonias has increased dramatically since the 1960s, particularly in immunocompromised patients. Fungal infections may be divided into endemic and opportunistic varieties. In general, the truly pathogenic (endemic) fungi infect healthy individuals, and opportunistic fungi usually infect only immunocompromised hosts. Almost all common fungal infections are acquired by inhalation of contaminated soil, resulting in pulmonary infections. Once in the lungs, the fungi elicit tissue responses ranging from acute exudative reactions to granulomatous reactions. The pulmonary lesions may resolve, progress to a prolonged chronic course, or disseminate to other organs, resulting in systemic infections. The diagnosis of fungal infection depends on the demonstration of the organisms by culture or histology; serologic tests may confirm the diagnosis. Fungi in tissues can be identified by hematoxylin and eosin stains, but special stains such as Gomori's methenamine silver and periodic acid-Schiff reagent are often required for diagnosis.

Humans↗
PubMed1991

The decedent affairs office. A unique centralized service.

The success of a centralized decedent affairs office depends on support by clinicians, the department chairman, and hospital administration. The benefits to the institution include improved public relations with a decedent's family, compliance with state and federal laws, increased organ donations, and better risk management programs. The only drawback of establishing such an office is the additional personnel necessary for 24-hour coverage. However, modifications in the functions and staffing levels of a decedent affairs office may be made, depending on the needs of individual institutions. We hypothesized that consent for autopsy would be easier to obtain and cause less emotional upheaval for family members if procedures were well established and specially trained individuals were involved in the process. With these ideas in mind, we established a decedent affairs office at The University of Texas Medical Branch in 1984.

Autopsy↗
PubMed1991

Purification and characterization of human muscle glutathione S-transferases: evidence that glutathione S-transferase zeta corresponds to a locus distinct from GST1, GST2, and GST3.

Human muscle glutathione S-transferase isozyme, GST zeta (pI 5.2) has been purified by three different methods using immunoaffinity chromatography, DEAE cellulose chromatography, and isoelectric focusing. GST zeta prepared by any of the three methods does not recognize antibodies raised against the alpha, mu, or pi class glutathione S-transferases of human tissues. GST zeta has a blocked N-terminus and its peptide fingerprints also indicate it to be distinct from the alpha, mu, or pi class isozymes. As compared to GSTs of alpha, mu, and pi classes, GST zeta displays higher activities toward t-stilbene oxide and Leukotriene A4 methyl ester. GST zeta also expresses GSH-peroxidase activity toward hydrogen peroxide. The Kms of GST zeta for CDNB and GSH were comparable to those reported for other human GSTs but its Vmax for CDNB, 7620 mol/mol/min, was found to be considerably higher than that reported for other human GSTs. The kinetics of inhibition of GST zeta by hematin, bile acids, and other inhibitors also indicate that it was distinct from the three classes of GST isozymes. These studies suggest that GST zeta corresponds to a locus distinct from GST1, GST2, and GST3 and probably corresponds to the GST4 locus as suggested previously by Laisney et al. (1984, Human Genet. 68, 221-227). The results of peptide fingerprints and kinetic analysis indicate that as compared to the pi and alpha class isozymes, GST zeta has more structural and functional similarities with the mu class isozymes. Besides GST zeta several other GST isozymes belonging to pi and mu class have also been characterized in muscle. The pi class GST isozymes of muscle have considerable charge heterogeneity among them despite identical N-terminal sequences.

Amino Acid Sequence↗