Individual Variability of Carbonyl Reductase Activity for Acetohexaminde in Human Erythorcytes

Acetohexamide, an oral antidiabetic agent, is metabolized by carbonyl reductase to hydroxyhexamide, which has a higher hypoglycemic potency than the parent compound. In the present study, interindividual variability of carbonyl reductase activity in erythrocyte was examined. Enzyme activity in 31 healthy subjects (23.9 plus minus 3.4 years, mean plus minus SD) was monitored by measuring formation of hydroxyhexamide using HPLC methods. Using 0.5 mM acetohexamide as substrate, reductase activity of 6.06 plus minus 0.06 nmol min(minus sign1) gHb(minus sign1) (range: 5.9--6.2) with a coefficient of variation of 15% was observed in erythrocytes. Acetohexamide-reducing activity in erythrocytes showed a normal distribution and the interindividual variability of the reductase activity was found to be small, implying that the large variability reported for the acetohexamide plasma half-life is not caused by the amount of reductase enzyme in erythrocytes.     

Polymorphisms of the human homologue of the Drosophila white gene are associated with mood and panic disorders

The Drosophila white gene is a member of the ATP-binding cassette (ABC) transporter superfamily and is involved in the cellular uptake of tryptophan. Its human homologue gene (hW) has been mapped to chromosome 21q22.3. Tryptophan is the precursor for the neurotransmitter serotonin, which has been implicated in the regulation of mood and anxiety. The locus 21q22.3 has also been reported to be associated with mood disorders. The 3'-untranslated region (3'-UTR) in the hW gene has been shown to contain a polymorphic poly(T) region. We have identified a new polymorphism G2457A in the 3'-UTR in the present study. We examined the relationship between these polymorphisms and mood and panic disorders, and a significant association between the poly(T) polymorphisms and mood disorders was detected (P=0.039 (allele frequency)). Associations were found between the polymorphisms and mood (poly(T) polymorphism: P=0.047 (allele frequency), G2457A: P=0.040 (allele frequency), P=0.044 (genotype frequency)) and panic disorders (G2457A: P=0.026 (allele frequency), P=0.011 (genotype frequency)) in males, but not in females. These findings suggest that the hW gene may be an important gene in the control of mood and anxiety as well as one of the genetic factors related to mood disorders and panic disorder in males. The statistical significance of the association remains relatively low and larger materials facilitating further dissection of the clinical phenotype will be needed to confirm and independently validate this finding and to evaluate its significance.     

An experimental study of radiation-induced cognitive dysfunction in an adult rat model

The objectives of this study were to establish an adult rat model for the late onset of radiation-induced cognitive dysfunction and to compare behavioural dysfunction with histopathological changes. While under anaesthesia, 30 rats (experimental group) were irradiated with a total dose of 40 Gy, given as eight fractions in 24 days. Another 30 rats (control group) underwent sham irradiation. The cognitive functions of all rats were evaluated at 6, 9 and 12 months after irradiation using the Morris water maze and passive avoidance tasks. Histopathological examination of these rats was carried out after the evaluation of cognitive functions was complete. At 6 and 9 months after irradiation there were no significant differences between the control and irradiated groups in passive avoidance and water maze tests. At 12 months after irradiation, the passive avoidance task revealed a deterioration of cognitive function in the experimental group. Histopathological observations revealed no abnormal findings in the irradiated brains at the light microscope level. Late onset cognitive dysfunction following cranial irradiation was observed in an adult rat model. Pathological investigations showed no abnormalities in the irradiated brains. These findings indicate that radiation-induced cognitive dysfunction can precede morphological changes in the brain or that they arise without them. The present model seems useful for elucidating the pathogenesis of radiation-induced cognitive dysfunction and for developing methods for therapy and prophylaxis.     

Changes in immune function following surgery for esophageal carcinoma.

Changes in immune function due to surgical injury have been well-documented. Immunosuppression is one of the causes of infectious complications leading to organ dysfunction in critical illness. It is not known what kind of surgery in the daily clinical practice causes immunosuppression. Stress response and immune function following surgery for esophageal carcinoma, assuming a highly-stressed operation, were studied and then compared with the stress response and immune function following gastric surgery, a moderately-stressed procedure. Forty patients who underwent esophagectomy and 39 patients receiving gastric operation were studied. The concentrations of serum interleukin-6 (IL-6) were measured preoperatively, at 1, 2, and 6 h, and at 1, 3, and 10 d after operation. Total protein, serum albumin, rapid turnover protein, serum CRP, and cortisol were measured before operation and at 1, 3, 7, and 21 d after operation. ConA- and PHA-stimulated lymphocyte proliferation, IgA, IgG, and IgM were also measured preoperatively, and on 7 and 21 d following surgery. The patients were fed exclusively by total parenteral nutrition (TPN). A striking rise of IL-6 was observed, with a peak in both groups at 1 to 6 h following operation. The peak values were 419+/-30 pg/mL, which was approximately twice as high in the esophagectomy patients as in the gastrectomy patients (195+/-40 pg/mL). CRP and cortisol also increased after operation, and these increases were also significantly greater in the esophagectomy patients. ConA- and PHA-stimulated lymphocyte proliferation decreased significantly 7 d after esophagectomy (P<0.05), but was unchanged in the patients receiving gastrectomy. Suppression of cellular immunity correlated significantly with serum cortisol, and was preceded by a rise in serum IL-6. The IgA, IgG, and IgM levels, however, remained unchanged from their preoperative values throughout the study in both groups. Nutritional status in terms of serum protein, albumin, and rapid turnover protein, decreased postoperatively, but there was no difference between the two groups. It is, therefore, concluded that cell-mediated immunosuppression, preceded by a hyperinflammatory response, is an observable reaction in patients following esophageal surgery, but not in patients undergoing gastric surgery.     

Control of the dispersing process and pharmacokinetics in rats for lipid A analogue, E5531.

E5531 is a synthetic disaccharide analogue of lipid A which has a low toxicity but retains the ability to reduce production of tumour necrosis factor. This analogue has potential for use in the treatment of septic shock. An injectable formulation of E5531 would be useful, but dispersion in aqueous solution is a problem. In the present study the dispersing process for E5531 was evaluated using the pH-jump method (pH 11.0-->7.3). The size of the aggregates was decreased (reaching 20 nm) with increasing dispersing time in 0.003 M NaOH (pH 11.0). The membrane fluidity of the aggregates increased with increasing dispersing time. When prepared by the normal dilution method (pH 7.3-->7.3), the size of the aggregates remained constant at 140 nm and the membrane fluidity was smaller than that of samples prepared by the pH-jump method. This indicates that during dispersing at basic pH, the hydration proceeded in a normal manner, but then stopped, just after adjustment of the pH to 7.3. This suggests that the degree of hydration of the membrane is dependent on the dispersing time at pH 11.0. Using samples with different degrees of hydration and different membrane fluidity prepared by the pH-jump method, the pharmacokinetics and stability of the aggregates were evaluated after intravenous injection into rats. The data thus obtained confirmed that the membrane fluidity was correlated with the pharmacokinetics and stability in rat plasma. It was concluded that the pharmacokinetics of E5531 in rats can be controlled by changing the degree of hydration and membrane fluidity by means of using different dispersing times in alkaline solution (pH 11.0).     

Tomographic analysis of CBF in cerebral infarction

Cerebral perfusion was examined in various types of occlusive disease by computed tomographic CBF method. The method utilized has several advantages over conventional studies using isotope, providing high resolution images in a direct relation to CT anatomy. Ten representative cases were presented from 25 consecutive cases of occlusive disease studied by this method. The method included inhalation of 40 to 60% xenon with serial CT scanning for 25 min. K (build-up rate), lambda (partition coefficient) and CBF values were calculated from HU for each pixel and Xe in expired air, based on Fick's principle, and displayed on CRT as K-, lambda- and CBF-map separately. CBF for gray matter of normal control was 82 +/- 11 ml/100 gm/min and that for white matter was 24 +/- 5 ml/100 gm/min. The ischemic threshold for gray matter appeared to be approximately 20 ml/100 gm/min, as blood flow in focus of complete infarction was below this level. Blood flow between 20-30 ml/100 gm/min caused some change on CT, such as localized atrophy, cortical thinning, loss of distinction between gray and white matter and decreased or increased density, which were considered to be compatible with pathological changes of laminar necrosis or gliosis with neuronal loss. In a case with occlusion of middle cerebral artery with subsequent recanalization, causing hemorrhagic infarct, hyperemia was observed in the infarcted cortex that was enhanced by iodine. Periventricular lucency observed in two cases, where blood flow was decreased below threshold, could be classified as "watershed infarction" mainly involving white matter. In moyamoya disease, blood flow in the anterior circulation was decreased near ischemic level, whereas that in basal ganglia and territory of posterior cerebral artery was fairly preserved, which was compatible with general angiographic finding of this disease.     

Histochemical and ultrastructural observations on brown degeneration of human intervertebral disc

Thirty-eight fresh human intervertebral discs collected during anterior interbody fusion surgery were histochemically and ultrastructurally analyzed for pigments. Macroscopically, five stages of degeneration were classified according to the color, fibrosis, and fragility of the nucleus pulposus of the discs. In order to demonstrate lipofuscin granules, specimens were subjected to special staining procedures, including carbol fuchsin lipofuscin stain, the Schmorl's reaction, and autofluorescence. Lipofuscin granules were distributed from the inner layer of the annulus fibrosus to the nucleus pulposus. Such granules were numerous in cases of slight or severe degeneration, whereas fewer granules were found in cases of moderate degeneration. However, the stage of macroscopic degeneration of the intervertebral disc did not necessarily correlate with the incidence of lipofuscin granules. By ultrastructural observation, the morphological features of the components of the intervertebral disc and the ultrastructure of the lipofuscin granule were clarified. The ultrastructure of the "brown degeneration" disc exhibited markedly increased amorphous electron-dense bodies located among collagen fibrils in the matrix.     

Characterization of rat hyperplastic bile ductular epithelial cells in culture andin vivo

A novel intrahepatic biliary cell culture/in vivo transplantation system has been developed with an essentially pure population of bile ductular epithelial cells isolated from rat liver 6–12 weeks after bile duct ligation. In primary culture, these cells retain staining strongly for -glutamyltranspeptidase and glutathione S-transferase P. The cytoplasm of cultured bile ductular cells reacts with an anti-laminin antibody, but loses immunoreactivity with a monoclonal anti-cytokeratin 19 antibody. Semiconservative DNA synthesis in the cultured cells was dependent upon the continued presence of 10% fetal calf serum in the medium. Replicating bile ductular cells could be subcultured for a finite number of passages. In addition, freshly isolated bile ductular epithelial cells gave rise to well differentiated bile ductular structures when transplanted into the interscapular fat pads of syngeneic recipient rats.Presented at the Proceedings of the International Meeting on Normal and Neoplastic Growth in Hepatology, Bari, Italy, June 1989.This work was supported by USPHS Grant RO1 CA39225 to Dr. Sirica by the National Cancer Institute, Department of Health and Human Services.