Effects of steroid on diaphragmatic functions in rabbits

The effects of steroid on diaphragmatic contractility and endurance were examined in 24 New Zealand rabbits. Diaphragmatic contractility was determined by measuring gastric pressure (Pga) with the lower thorax and the abdomen of the animal being fixed with a rigid cast. Endurance procedure was done by continuous 15 Hz stimulation of the bilateral phrenic nerves, and diaphragmatic endurance was expressed as the time from the initiation of the endurance procedure to the moment when transdiaphragmatic pressure 15 Hz (Pdi-15 Hz) decreased to 25% of Pdimax-15 Hz. Our data suggested that intravenous administration of dexamethasone 2.5 mg daily for 7 days did not affect the diaphragmatic contractility significantly, but could cause a significant decrease in diaphragmatic endurance. When delivered intravenously at the dose of 2.0 mg daily for 14 days, dexamethasone induced a significant decrease both in diaphragmatic contractility and endurance. The recovery of the diaphragmatic strength from fatigue, however, was not influenced by dexamethasone in either circumstance. The influence of dexamethasone on diaphragmatic contractility and endurance may have important clinical implications.

Rothmund-Thomson syndrome in fraternal twins

Fraternal twins of Malay descent had the Rothmund-Thomson syndrome. This is a rare, autosomal recessive disorder characterized by photosensitivity, poikiloderma, short stature, skeletal defects, and juvenile cataracts. This is the first case report of the syndrome from southeast Asia.

Fixing of photorefractive volume holograms in K(1-y)Li(y)Ta(1-x)O(3)

We report the fixing of photorefractive holographic gratings with high efficiency in a sample of K(1-y)Li(y)Ta(1-x)Nb(x)O(3) doped with Cu, V, and Ti. Holograms are thermally fixed through the screening of a photorefractive space-charge f ield by a nonphotoactive species at elevated temperatures. Fixed holograms are revealed by illumination at lower temperatures. Diffraction efficiencies of 25% in a 0.54-cm-thick sample are measured. Holograms undergo thermal decay with a 0.67-eV activation energy.

A review of dermatomyositis cases at Hospital Besar Kuala Lumpur 1989-1993

Eight cases of dermatomyositis were seen in the Skin Department, Hospital Besar Kuala Lumpur between 1989 and 1993. There was one case of juvenile dermatomyositis. There was a majority of Chinese patients (87.5%). There were three patients (37.5%) with underlying malignancies, two of which (66.7%) were nasopharyngeal carcinomas; all were under the age of fifty years. It is important to screen all adult patients for underlying malignancies, even those in the younger age group.

Combined therapy of captopril and spironolactone for refractory congestive heart failure

It is traditionally considered that angiotensin--converting enzyme inhibitor (ACEI) and spironolactone could not be used simultaneously because of the assumed risk of hyperkalemia. However, despite ACEI therapy edema and congestive status remain in some of the patients with severe congestive heart failure (CHF). In order to seek an effective therapy for these patients, we observed the efficacy and safety of captopil plus spironolactone in patients with refractory CHF, with strict monitoring of renal function, serum and urine electrolytes and blood pressure (BP). Thirty-five patients with refractory CHF and New York Heart Association functional class IV without renal dysfunction, hypotension and hyperkalemia, whose plasma aldosterone (ALD) level in 88.6% of them was above normal value, were randomly assigned to group A (n = 16, captopril alone) and B (n = 19, captopril plus spironolactone) for a 4-week treatment. The dosage of both drugs was individually adjusted in time according to the results of serum potassium and renal function. The improvement in dyspnea--fatigue ratings, urinary volume and Na+/K+ ratio in group B was more significant than that in group A, and the plasma ALD level in group B decreased obviously while it remained high in group A after therapy. Two patients in group B who had had normal plasma ALD level with urinary Na+/K+ ratio > 1.0 before the therapy did not exhibit any clinical improvement. A strong negative correlation was found between plasma ALD level and urinary Na+/K+ ratio (correlation coefficient -0.689, P < 0.01). None of the patients had obvious hyperkalemia and hypoaldosteronism.(ABSTRACT TRUNCATED AT 250 WORDS)

[A study of captopril enhancement of nitrate effect coronary arterial disease patients associated with heart failure]

It is shown in a prospective study that the initial beneficial hemodynamic effect of nitroglycerine (NTG) significantly decreased after continuous 3-day infusion of this drug (10-50 micrograms/min) in acute myocardial infarction (AMI) patients associated with acute left heart failure. The effect of ameliorating anginapectoris and improving heart function with isosorbide dinitrate (ISDN) gradually decreased almost to pretreatment levels after oral administration of this drug (10-20mg, 4 times daily) for 3 weeks in anginapectoris patients associated with congestive heart failure (CHF) with accompanying increased level of plasma angiotensin II (AII) and body weight. However, when captopril (CPT, 12.5-25mg, 3 times daily) was combined with nitrates, the clinical effects were enhanced and maintained throughout the study, along with a decrease in the level of AII and body weight. In the hearts of rats perfused with CPT and NTG, the coronary flow (CF) significantly increased as compared with the flow when either drug was used alone. Enelapril (ENL, a non-sulfhydryl drug), however, did not show such effect. The above results indicate that repletion of sulfhydryl to vascular smooth muscle and antineurohumoral activation may be the potential mechanisms by which CPT reverses nitrate tolerance and enhances its clinical effects.

Comparative studies of the core gene products of two different hepatitis C virus isolates: two alternative forms determined by a single amino acid substitution

We have compared the expression of the core gene of two different hepatitis C virus (HCV) isolates, HCV-1 and HCV-RH, using the in vitro translation assay. In the absence of the downstream E1 envelope protein sequence, a 16-kDa protein (P16) was the dominant protein product synthesized from the HCV-1 core gene sequence. On the other hand, a 21-kDa protein (P21) was the dominant protein product synthesized from the HCV-RH sequence. Domain-swapping and site-directed mutagenesis experiments indicated that codon 9 of the core protein coding sequence played a crucial role on the synthesis of the core protein: a lysine codon at this position led to the synthesis of P16 and an arginine codon at this position led to the synthesis of P21. For HCV-1 and HCV-RH, this codon encodes lysine and arginine, respectively. Further analyses indicated that P16 was likely co-amino-terminal with P21. In the presence of the downstream E1 envelope protein sequence and microsomal membranes, P16 as well as P21 were synthesized from the HCV-1 core gene sequence whereas P21 remained the only detectable protein product synthesized from the HCV-RH core gene sequence. These results indicate that the pathway leading to the synthesis of the HCV core protein may be more complicated than originally envisioned.

Confocal imaging of the alpha 6 and beta 4 integrin subunits in the human cornea with aging

PURPOSE

The purpose of this study was to examine changes in the distribution of integrin subunits, alpha 6 and alpha 4, in the normal human cornea with age.

METHODS

Thirty normal corneas were examined and divided into three groups; corneas from children younger than 2 years, corneas from adults 29 to 70 years, and corneas from adults older than 70 years. The corneas were frozen and the sections were cut, double-stained with monoclonal antibodies to the integrin subunits, and visualized with Texas Red or fluorescein using confocal laser scanning microscopy. Computer imaging was conducted to determine differences.

RESULTS

The alpha 6 subunit was generally localized along the basal and lateral surfaces of basal epithelial cells and projected into Bowman's membrane. The beta 4 subunit was only present along the basal surface. Overall, the major age-related difference was the loss of continuous alpha 6 and beta 4 subunits along the basal surface of basal epithelial cells. When reconstructed images from corneas of individuals older than 70 years were optically sectioned en face, the alpha 6 subunit appeared discontinuous. If the same optical images were viewed from corneas of younger individuals, the staining was continuous. The number and distribution of hemidesmosomes along the basal lamina did not change with age in the corneas examined.

CONCLUSIONS

Using computer imaging associated with confocal laser scanning microscopy, we have demonstrated that there is an age-related change in the localization of the alpha 6 and beta 4 subunits.

Expression of multidrug resistance (p-glycoprotein) mdr1 and mdr2 genes in human hepatocellular carcinomas and liver metastases of colonic tumors

Overexpression of P-glycoproteins (P-gp), encoded by multidrug resistance (MDR) genes is responsible for multidrug resistance in animal cells. We analyzed the expression of MDR genes in human hepatocellular carcinomas (HCC) and liver metastases of colon tumors by an RNase protection assay. Our results indicated that both genes were not consistently overexpressed in these tumors, whereas MDR2 is often underexpressed in the metastatic tumors. Invasion of colon tumors to livers decreased MDR1 expression. These data suggest differential regulation mechanisms for the expression of MDR1 and MDR2 genes in these tumors, and a complex drug-resistance mechanism for liver cancers.

[Effect of captopril on the exercise performance in patients with congestive heart failure]

We studied the effect of captopril on exercise performance in 30 patients with congestive heart failure using a randomized, double-blind and placebo-controlled method. 4-week captopril treatment can significantly increase the exercise tolerance time and work load, heart function, blood flow in exercising lower limbs as well as oxygen metabolic capacity. However, 3-day captopril treatment had no effect on exercise performance. A significant correlation was found between improvement in exercise performance and the pretreatment level of plasma angiotensin II. The increased levels of plasma prostaglandins E 2 and I 2 after captopril treatment were also correlated with improvement of exercise performance. The results indicated that long-term captopril treatment can increase exercise performance in congestive heart failure by improving both central and peripheral hemodynamics and metabolism. Certain vasomotor or endocrine factor may play a mediate role in the above changes.

Properties of the exchangeable splenic platelets released into the circulation during exercise-induced thrombocytosis

The human spleen normally retains about one-third of the body's platelets in an exchangeable pool which can be released into the circulation by alpha-adrenergic stimulation. Some previous investigators concluded that the splenic platelet population was enriched in a subpopulation of large, young, dense platelets (megathrombocytes) but more recent research suggests that platelet size, age, and density are largely independent variables. In this investigation the properties of the splenic platelets were studied after their release into the circulation by acute strenuous exercise in 11 normal subjects. The exercise caused a rise in mean platelet count from 245 +/- 49 to 328 +/- 71 x 10(9)/L--a net increase of 24 +/- 6% after correction for haemoconcentration. The mean platelet volume (MPV) of citrated platelets increased from 6.38 +/- 0.78 to 6.59 +/- 0.68 fL after exercise (P less than 0.01)--a rise of 3.7 +/- 4.1% suggesting that the MPV of the splenic platelet population was about 20% greater than that of the normal circulating population. The age distribution of the platelets was studied by measuring the platelet monoamine oxidase (MAO) activity several days after irreversible inhibition by tranylcypromine, when the young platelets had normal MAO activity but the older platelets had only 20% of normal activity. The mean platelet MAO activity did not change after exercise, indicating that the age distributions of the circulating and splenic populations were very similar. The platelet contents of several putative markers of platelet age (sialic acid, serotonin, beta-thromboglobulin, beta-N-acetylglucosaminidase) were also unchanged after exercise. Modal platelet density decreased slightly but not significantly after exercise. The splenic platelet population has a larger MPV but appears to have similar age and density distributions to the basal circulating population.

The relationship of human platelet density to platelet age: platelet population labeling by monoamine oxidase inhibition

The relationship between platelet density and platelet age appears to vary between species with relatively few labeling studies in humans reported. In this study, irreversible monoamine oxidase (MAO) inhibitors were used to biochemically label the circulating platelet population in 15 humans. Platelet samples were then isolated during the 15 days after drug ingestion. The platelets were separated by density on continuous linear Percoll gradients and the density distributions were divided into five fractions containing approximately equal numbers of platelets. Baseline MAO activity was strongly correlated with platelet density. Twenty-four hours after a single dose of tranylcypromine, platelet MAO activities in the density subpopulations were reduced to 14% to 17% of the baseline values. During the first five days after inhibition, the rates of recovery of MAO activity (percentage per day) were inversely proportional to platelet density. The recovery rates in the two most dense fractions were initially slow but increased after five days. Percentage recovery of MAO activity in the least dense fraction was significantly greater than the percentage recovery in the most dense fraction on days 2, 3, 5, and 8 (P less than .01, sign test). These results support the hypothesis that normal human platelets show a small increase in density with age, but they do not exclude the additional possibility that human platelet lifespan is positively correlated with platelet density.

The use of monoamine oxidase inhibition to estimate megakaryocyte-platelet regeneration time (MPRT)

The megakaryocyte-platelet regeneration time (MPRT) was measured in 16 normal subjects after irreversible monoamine oxidase (MAO) inhibition. When ten subjects were given a single 20 mg dose of Parnate (tranylcypromine) the mean MPRT was 242 +/- 20 hours (linear model) or 212 +/- 22 hours (weighted mean model) with a mean %-linearity of 75 +/- 22%. The renewal of platelet MAO activity was initially retarded for about 2 days, suggesting that inhibition of megakaryocyte MAO had occurred. Six subjects who had taken MAO inhibitors daily for 1-6 months gave longer MPRT values (274 +/- 57 hours (lin.) or 246 +/- 67 hours (w. m.)), but the differences between the groups were not statistically significant. The single-dose MPRT results agree well with those obtained using the irreversible inhibition of cyclo-oxygenase by aspirin, but exceed the platelet life-spans estimated using radiochemical methods by about 24-36 hours. Platelet serotonin levels did not change significantly after a single dose of Parnate, but supine systolic blood pressure rose by 9 +/- 7 mm Hg (p less than 0.01) 24 hours after the dose. Estimation of MPRT by MAO inhibition is a useful alternative to the aspirin method but screening of subjects and clinical supervision is needed to avoid hypertensive complications.

Proplatelets and stress platelets

The process of platelet formation by the fragmentation of megakaryocyte pseudopodia, termed proplatelets, demonstrable in the marrow sinusoids is poorly understood. "Stress" platelets produced under conditions of stimulated platelet production differ from normal circulating platelets with respect to volume and a number of functional characteristics. To clarify the relationship of stress platelets to proplatelets, rats were injected with heterologous platelet antiserum. Nondiscoid platelet forms, some characteristically beaded in appearance, strongly resembling bone marrow proplatelets, can be recovered in the circulation of normal rats. During the early period of recovery from acute thrombocytopenia, there was a substantial increase in the proportion of these elongated platelets in the citrated platelet rich plasma. Exposure to EDTA rendered them spherical. Circulating proplatelets may contribute significantly to the prompt increase in platelet volume during recovery from acute thrombocytopenia at a time prior to significant increase in megakaryocyte size and ploidy.

Enzyme Immunoassay for Detection of Salmonella in Foods: Collaborative Study

A collaborative study was performed in 25 laboratories to validate an enzyme immunoassay (EIA) procedure utilizing 2 specific monoclonal antibodies for rapid detection of Salmonella in foods. The EIA was compared with the standard culture procedure for detection of Salmonella in 6 food types: ground black pepper, soy isolate, dried whole eggs, milk chocolate, nonfat dry milk, and raw deboned turkey, Uninoculated and inoculated samples were included in each food group analyzed, with the exception of poultry which was naturally contaminated. There was no significant difference in the productivity of the EIA and culture procedures at the 5% level for any of the 6 foods. The enzyme immunoassay screening method has been adopted official first action.

The safety of the hepatitis B vaccine. Inactivation of the AIDS virus during routine vaccine manufacture

In the United States, one hepatitis B vaccine (Heptavax-B) has been licensed for the prevention of hepatitis B virus infections. Even though this vaccine has been shown to be highly effective and well tolerated in controlled trials and has been recommended for use in those at risk for acquiring infection by hepatitis B virus, many individuals have been reluctant to be immunized for fear of contracting acquired immunodeficiency syndrome (AIDS). In this study, we demonstrate that each of the three inactivation steps used in the manufacture of Heptavax-B independently will inactivate the infectivity of high-titered preparations of the AIDS virus; recipients of the hepatitis B vaccine do not develop antibodies to the AIDS virus; the hepatitis B vaccine does not contain detectable levels of nucleic acids related to the AIDS virus. These observations clearly demonstrate that vaccination with the currently available hepatitis B vaccine poses no demonstrable risk for acquiring AIDS.

Pathological spectrum of liver diseases in sickle cell disease

Most pathologic studies of liver disease in sickle cell anemia and its variants were performed retrospectively on autopsy specimens, and, because of the prominent histologic features of intrasinusoidal sickling and Kupffer cell erythrophagocytosis, hepatic dysfunction was attributed to the intrahepatic sickling of erythrocytes in this hemoglobinopathy. We compared the liver histology from 19 patients who had liver biopsies to the autopsy specimens from 32 patients who succumbed to the complications of the hemoglobinopathy. In the former, nine patients had histological evidence of viral hepatitis. Four of these patients had both serological and immunohistochemical evidence of hepatitis B surface antigen. The features of biliary tree obstruction were found in two cases and alcoholic cirrhosis and sarcoid granuloma in one case each. Only one patient, who had recovered from septic shock, showed ischemic necrosis. In five patients incidentally biopsied during cholecystectomy, no significant lesions were found. Fourteen of the autopsy specimens showed ischemic necrosis, a result which was significantly different from the biopsy group. Ten cases had no significant morphologic changes other than heavy iron deposits. There were two cases with chronic active hepatitis, two with diffuse fibrosis, and one case each of cirrhosis, acute viral hepatitis, cholestasis, and giant cell hepatitis. Intrahepatic sickling and erythrophagocytosis were seen in almost all specimens and did not correlate with liver disease or transaminase elevation. Other than the patient with septic shock, ischemic necrosis was found only in postmortem material. These histological features may represent red cell destruction rather than the etiology of liver disease in these patients.

Hepatocellular carcinoma. Diagnostic and prognostic features in North American patients

Diagnostic and prognostic characteristics of 121 North American patients with hepatocellular carcinoma seen in one metropolitan area over a 6-year period were assessed using multivariate analysis. Presenting symptoms commonly included abdominal pain (53%) or mass (34%), anorexia (31%), and ascites (20%); however, the ability to make an early diagnosis was complicated by a variety of unusual symptoms accounting for 25% of presentations. While cirrhosis (63%) and hepatitis B surface antigen (HBsAg) positivity (52%) were common associated findings, the majority of patients (67%) had no prior diagnosis of liver disease. Despite the vascular nature of these malignancies, percutaneous biopsy procedures performed in 66 patients provided diagnostic material in over 85% of cases with little morbidity. Histologic diagnosis was made by blind percutaneous biopsy (41 done, 83% positive), peritoneoscopy with directed percutaneous biopsy (25 done, 88% positive), laparotomy (42 done, 98% positive), or autopsy (19). Percutaneous hepatic biopsy procedures were associated with no mortality and rare bleeding (three cases). Overall median survival was only 18 weeks; multivariate analysis indicated increased bilirubin or presence of pulmonary metastases adversely influenced outcome. Unexpectedly, patients younger than 45 years of age had a significantly (P less than 0.01) greater survival (median, 40 versus 9 weeks) than did older patients with this disease. We conclude: (1) hepatocellular carcinoma can be rapidly and safely diagnosed using percutaneous biopsy procedures; (2) North American patients with hepatocellular carcinoma younger than 45 years of age have a more favorable prognosis.