[The levels of renin activity, angiotensin converting enzyme and angiotensin II in cirrhotic patients with ascites undergoing portacaval shunt]

OBJECTIVE

To investigate the changes of plasma renin activity (PRA), angiotensin converting enzyme (ACE), angiotensin II and portal venous pressure (PVP) in cirrhotic patients with ascites undergoing portacaval shunt.

METHODS

Serum PRA, ACE, A II levels in portal vein, artery, peripheral vein and PVP were measured in 16 cirrhotic patients with ascites before and after portacaval shunts and in control group of 16 cases of gastrointestinal carcinoma. By light colorimetric analysis and radio-immunization assay.

RESULTS

PRA, ACE, A II levels and PVP of pre- and after portacaval shunt were significantly higher in cirrhotic patients than the control group (P < 0.05), and they were significantly decreased after the shunt in the cirrhotic patients (P < 0.05). The PVP was in positive correlation to the levels of serum ACE in cirrhotic patients (r = 0.48, P < 0.01).

CONCLUSIONS

The levels of serum PRA, ACE, A II and PVP decreased significantly in cirrhotic patients with portal hypertension after portacaval shunts. It may be major causes of ascites disappearance in cirrhotic patients after portacaval shunt.

Within-subject variability in cocaine pharmacokinetics and pharmacodynamics after intraperitoneal compared with intravenous cocaine administration

Performance in rats (Rattus norvegicus) was measured on a differential reinforcement of low-rate schedule (DRL 45-s) in 1.5-hr sessions after 2 mg/kg intravenous (i.v.) or 10-20 mg/kg intraperitoneal (i.p.) cocaine administration, with each dose given twice and separated by 3-5 days. For successive i.v. doses, cocaine effects were similar, with minimal within-subject variability. For i.p. cocaine, the effects were not always similar; performance was variable and sometimes remained at baseline level. These diminished effects occurred following either the 1st or 2nd i.p. injection. A parallel pharmacokinetic study of cocaine confirmed that within-subject variability existed in cocaine concentration-time profiles after i.p. cocaine, and that a low serum cocaine concentration-time profile could account for the diminished effects. The i.p. route for cocaine administration should be used with caution.

Pharmacokinetic-pharmacodynamic modeling of the psychomotor stimulant effect of cocaine after intravenous administration: timing performance deficits

We investigated dose-response cocaine pharmacokinetic and metabolite profiles in a within-subject design after intravenous bolus cocaine administration (1-4 mg/kg) in rats under a food-limited regimen. Cocaine was rapidly distributed (T1/2beta = 1.09 min) and eliminated (T1/2alpha = 14.93 min). Norcocaine was not detected. The free fraction of cocaine was 31.3-33.1% for serum cocaine concentrations of 0.5 to 1 microg/ml. Parallel pharmacodynamics was studied using performance on a contingency-controlled timing behavior, a differential reinforcement of low rate schedule (45 s) in 3-h sessions. Cocaine increased the shorter-response rate and decreased the density of reinforcement in a dose- and time-related fashion. The increased shorter-response rate is the stimulatory effect herein reported. The changes in shorter-response rate and the density of reinforcement were directly interpretable as functions of cocaine concentrations in the respective hypothetical effect compartments by using sigmoidal Emax and inhibitory Emax models, respectively. Because the concentration at half of Emax for the shorter-response rate (EC50 = 0.467 microg/ml) was greater than that for density of reinforcement (IC50 = 0.070 microg/ml), the former began to return toward baseline sooner than the latter. Only as cocaine concentration decreased to values smaller than the EC50 did the density of reinforcement begin to return toward baseline. Thus, the density of reinforcement is an index for evaluating the deficit in timing performance. The concentration-effect plot confirmed that the intensity of the effects of cocaine depends solely on concentration regardless of the dose. These results demonstrated that the pharmacokinetic-pharmacodynamic analysis allows the identification of the stimulant action of cocaine, which in turn delineates its consequence on timing performance.

Race-specific cancer mortality in US firefighters: 1984-1993

A mortality odds ratio (MOR) study of race-specific cancer risk among firefighters was conducted using 1984-1993 death certificate data from 24 states. The Bureau of the Census Index of Industries and Occupations was used to code occupation on death certificates. The overall cancer mortality was slightly elevated among white firefighters (MOR = 1.1; 95% confidence interval [CI] = 1.1-1.2), but the increase in overall cancer mortality among black firefighters was not significant (MOR = 1.2; 95% CI = 0.9-1.5). Only prostate cancer risk was elevated in both groups (whites: MOR = 1.2; 95% CI = 1.0-1.3; blacks: MOR = 1.9; 95% CI = 1.2-3.2). Among white firefighters, elevated site-specific cancer mortality risks were found for the following cancer sites: lip (MOR = 5.9; 95% CI = 1.9-18.3), pancreas (MOR = 1.2; 95% CI = 1.0-1.5), soft tissue sarcoma (MOR = 1.6; 95% CI = 1.0-2.7), melanoma (MOR = 1.4; 95% CI = 1.0-1.9), kidney and renal pelvis (MOR = 1.3; 95% CI = 1.0-1.7), non-Hodgkin's lymphoma (MOR = 1.4; 95% CI = 1.1-1.7), and Hodgkin's disease (MOR = 2.4; 95% CI = 1.4-4.1). We also observed a slightly elevated risk for bronchus and lung cancer (MOR = 1.1; 95% CI = 1.0-1.2). Among black firefighters, excess risks were found for cancers of the brain and central nervous system (MOR = 6.9; 95% CI = 3.0-16.0), colon (MOR = 2.1; 95% CI = 1.1-4.0), and nasopharynx (MOR = 7.6; 95% CI = 1.3-46.4). Future studies are needed to confirm the existence of differential cancer mortality risks among firefighters of different race/ethnic subpopulations.

Diabetes and hearing impairment in Mexican American adults: a population-based study

Reports on the relationship between diabetes and hearing loss have been controversial. The present study examined this relationship in 1,740 Mexican American adults using data from the Hispanic Health and Nutrition Examination Survey. Hearing threshold levels were obtained for each participant at the following frequencies: 500, 1000, 2000, and 4000 Hertz (Hz). The thresholds from the worse hearing ear were used in the analyses. Diabetes and insulin use were assessed by self-report. The mean crude hearing thresholds in diabetics were significantly higher than in non-diabetics at each of the four frequencies. However, after adjustment for age, gender, and socioeconomic status, diabetics had a significantly higher mean threshold than non-diabetics only at 500 Hz (mean difference +/- SE: 2.8 +/- 1.2, p = 0.04). Diabetics who were not using insulin had significantly higher thresholds than those who were using insulin at 2000 (mean difference +/- SE: 5.6 +/- 2.6, p = 0.03) and 4000 Hz (7.7 +/- 3.3, p = 0.02). Also, at 4000 Hz, insulin users had a significantly lower mean threshold than non-diabetics (mean difference +/- SE: -4.9 +/- 1.6, p = 0.02). Our data suggest that associations between diabetes and decreased hearing acuity in the higher frequencies are present only amongst diabetic Mexican-Americans who do not use insulin.

Determination of clozapine and its metabolite, N-desmethylclozapine, in serum microsamples by high-performance liquid chromatography and its application to pharmacokinetics in rats

A single solvent extraction step high-performance liquid chromatographic method is described for quantitating clozapine and its metabolite, N-desmethylclozapine, in rat serum microsamples (50 microl). The separation used a 2.1-mm I.D. reversed-phase Symmetry C18 column with an isocratic mobile phase consisting of methanol-acetonitrile-28.6 mM sodium acetate buffer, pH 2.6 (10:20:70, v/v/v). The detection limit was 2.5 ng/ml for all the compounds using an ultraviolet detector operated at 230 nm. The method was used to study the pharmacokinetics of clozapine after an intravenous bolus dose (2.5 mg/kg).

[Effect of qingjieling induced endogenous granulocyte-colony stimulating factor in strengthening host defence against bacteria]

OBJECTIVE

To explore the effect of Qingjieling (QJL) induced endogenous granulocyte-colony stimulating factor (G-CSF) in strengthening host defence against bacteria in mice.

METHODS

Serum containing G-CSF was obtained by injecting 5 mg/g of QJL to mice. The CSF activity was identified by ELISA, bone marrow cell proliferation and colony-forming assays. Forty-eight hours after the serum was infused to 8 normal BALB/C mice, the mice was sacrificed and the number of E. coli in spleen suspension was measured. Eight mice of the control group were treated in the same way but with normal serum of mice instead of the QJL treated serum.

RESULTS

The QJL treated serum showed a positive reaction with anti-G-CSF McAb, it promoted the proliferation of bone marrow cells and formation of cell colony of neutrophilic granulocyte type in the culture medium, these results indicated that the serum contained G-CSF undoubtedly. The number of E. coli in spleen suspension of test group was significantly lower than that of the control group P < 0.01).

CONCLUSIONS

QJL does enhance the defense capability of the host, the mechanism of which partly might be due to the induction of endogenous G-CSF in the host.

[Histamine-1 and -2 receptors in hepatic tissues of cirrhotic patients with portal hypertension]

OBJECTIVE

To study histamine-1 and histamine-2 receptors in hepatic tissues of cirrhotic patients with portal hypertension.

METHOD

Light autoradiography was used.

RESULT

The density of histamine-2 (H-2) receptors (cirrhotic patients/controls) in hepatocytes was 168.4 +/- 22.6/511.9 +/- 37.6 (P < 0.01), in hepatic vein 238.8 +/- 40.7/313.0 +/- 52.4 (P < 0.01), in hepatic artery 55.6 +/- 7.1/175.4 +/- 26.1 (P < 0.01), and in portal vein 52.0 +/- 5.4/166.4 +/- 17.7 (P < 0.01). The density of histamine-1 receptors in hepatocytes, hepatic vein, hepatic artery and portal vein was not statistically changed between cirrhotic patients and controls (P > 0.05).

CONCLUSION

The density of H-2 receptors in hepatic tissues of cirrhotic patients decreased significantly.

Pharmacokinetic-pharmacodynamic modeling of the coexistence of stimulatory and sedative components for midazolam

Midazolam increased the shorter-response rate and decreased the reinforcement rate of a contingency-controlled timing behavior--a differential-reinforcement-of-low-rate 45-s schedule. The responding rate changes observed were immediately interpretable as functions of midazolam concentration during a 3-h session--a period for investigating the onset, peak, and disappearance of midazolam effect--in rats. That the midazolam pharmacokinetic-pharmacodynamic model was a direct application of our alprazolam pharmacokinetic-pharmacodynamic model implies that both drugs exhibit similar pharmacological effects. The two peaks of the shorter-response rate increases produced by midazolam were modeled as a stimulation-sedation model that consisted of two opposing effect-link sigmoidal Emax functions. The stimulation-sedation model suggested that midazolam possesses both stimulatory and sedative effects in a continuous but sequential fashion, and hypothesizes the coexistence of stimulation and sedation components for midazolam; this model may help delineate possible mechanisms for rebound side effects and of tolerance in humans. The reinforcement rate was, then, an index for evaluating the deficit in timing performance.

Establishment of a GM-CSF-dependent megakaryoblastic cell line with the potential to differentiate into an eosinophilic lineage in response to retinoic acids

We recently established a human granulocyte-macrophage colony-stimulating factor (GM-CSF)-dependent cell line (HML) from colony-constituent cells grown by peripheral blood cells of a patient with acute megakaryoblastic leukaemia. The HML cells possessed megakaryocytic features, as determined by cytochemical, electron microscopic and flow cytometric analysis. In the present study we examined the effects of retinoic acid (RA) on the development of HML cells. All-trans-RA, 13-cis-RA and 9-cis-RA at 10(-8) mol/l to 10(-5) mol/l inhibited the GM-CSF-dependent cell growth. Some of the RA-treated cells contained prominent azurophilic granules and were positive for peroxidase. They also reacted with Biebrich scarlet, Luxol fast blue and a monoclonal antibody against eosinophil peroxidase. In addition, exposure to RA increased the frequency and the intensity of major basic protein-positive cells. However, eosinophil-derived neurotoxin and eosinophil cationic protein were not detected or were only detected at a low level in the lysates of the HML cells treated with RA. Although IL-5 alone could not stimulate cell growth, the addition of IL-5 to the cultures containing stem cell factor + all-trans-RA was required for the expression of the eosinophilic phenotype. These results suggest that the HML cell line is a megakaryoblastic cell line with the potential to differentiate into the eosinophilic lineage. HML cells may be a useful model for elucidating the eosinophilic differentiation programme.

Evaluation of transforming growth factor beta and bone morphogenetic protein composite on healing of bone defects

OBJECTIVE

To evaluate the effect of transforming growth factor-beta/bone morphogenetic protein (TGF-beta/BMP) composite on the healing of large segmental bone defects and to discuss the interaction between TGF-beta and BMP during bone repair.

METHODS

A 1.5 cm segmental defect was made in the mid-upper part of the radial shaft of 48 adult rabbits. The defects were filled with implants of TGF-beta/carrier, BMP/carrier or TGF-beta/BMP/carrier separately. 120 micrograms of purified bovine TGF-beta and 12 mg of BMP were used in the composite. The defects were examined radiographically and histologically at 4, 8, 12 and 16 weeks post-operation.

RESULTS

In the group filled with TGF-beta/BMP composite, the defect areas were bridged at 4 weeks, with callus of uniform radiodensity. Cortices of the cut ends were obscured by new bone. By 16 weeks post-operation, the defects were bridged by uniform new bone and the cut ends of the cortex could not be seen in all groups. In group of BMP/carrier, the defects were filled with more irregular woven bone callus than in other two groups. TGF-beta/BMP implanted defects in animals killed at 16 weeks showed histologically new lamella and woven bone that was formed in continuity with the cut ends of the cortex. Medullar canal was recanalized and contained marrow elements with normal appearance.

CONCLUSIONS

These data demonstrate not only the synergistic action between TGF-beta and BMP in the process of bone healing, but also a better effect of TGF-beta/BMP composite than single TGF-beta or BMP on bone repair, especially in the early stage of bone repair process.

[Senility-preventing effect of erlingcankang decoction]

Experiments with Erlingcankang Decoction showed that when given to silk worms it could noticeably prolong the growth period of larvae and raise an average of 10-day survival of the male moths; when given to mice it could prolong their life; and when given to on old rats it could markedly raise the contents of SOD in the liver and red cells, lower the content of MAO-B in the brain, LF in the brain and adrenal gland and also LPO in the liver.

Determination of cocaine and its metabolites in serum microsamples by high-performance liquid chromatography and its application to pharmacokinetics in rats

A single-solvent extraction step high-performance liquid chromatographic method is described for quantitating cocaine and its three metabolites in rat serum microsamples (50 microl). The separation used a 2.1-mm I.D. reversed-phase Brownlee C18 column with an isocratic mobile phase consisting of methanol-acetonitrile-25.8 mM sodium acetate buffer, pH 2.2, containing 1.29-10(-4) M tetrabutylammonium phosphate (12.5:10:77.5, v/v/v). The detection limit was 2.5 ng/ml for all the compounds using an ultraviolet detector operated at 235 nm. The method was used to study the pharmacokinetics of cocaine after an intravenous (i.v.) bolus dose (4 mg/kg).

Role of transforming growth factor beta (TGF-beta) in repairing of bone defects

TGF-beta is a multifunctional cytokine that regulates many aspects of cellular function, including periosteal mesenchymal cell proliferation, differentiation. This experiment is to study its effects on bone defect repair. A rabbit radial bone defect model was used to evaluate the effect of TGF-beta, which was extracted and purified from bovine blood platelets, on the healing of a large segmental osteoperiosteal defect. A 1.5-centimeter segmental defect was created in the mid-upper part of the radial shaft of adult rabbits. The defect was filled with implant containing TGF-beta that consisted of carrier and bovine TGF-beta. Limbs served as controls received carrier alone. The defects were examined radiographically and histologically at 4, 8, 12, 16 and 20 weeks after implantation. The results showed that in TGF-beta implant group, the defect areas at 12 weeks post operation were bridged by uniform new bone and the cut ends of cortex could not be seen; while in control group, the defects remained clear. Only a small amount of new bone formed as a cap on the cut bone ends. In the experimental group, new lamellar and woven bone formed in continuity with the cut ends of the cortex. An early medullar canal appears to be forming and contained normal-appearancing marrow elements; while the control group displayed entirely fibrous tissue within the defect site. Remnants of the cancellous bone carrier were observed in the control specimen. These data demonstrate that exogenous TGF-beta initiate osteogenesis and stimulate the bone defects repair in animal model.

[An X-ray study of the density and orientation of the cutaneous arteries in the lower leg]

Angiography was performed on 10 legs of fresh cadavers to investigate the density and orientation of small arteries of the lower leg. It was revealed that there were more vertically arranged arteries than the horizontally arranged ones in the skin and superficial fascia. The entire surface of the lower leg was divided into 9 regions. The density of arteries of different orientations in the skin and fascia was measured regionally. Though the density of different regions had a significant difference, no statistical significant difference was found in vessel anastomosis rate between different regions. Where the density was high, the anastomoses were rich. According to these findings, suggestions for the design of random flaps in the lower leg were discussed.

Osteochondrogenic potential of marrow mesenchymal progenitor cells exposed to TGF-beta 1 or PDGF-BB as assayed in vivo and in vitro

Mesenchymal progenitors cells can be isolated from rat bone marrow and mitotically expanded in vitro. When these cells, which we operationally call mesenchymal stem cells (MSCs), are placed in an appropriate environment, they have the capacity to differentiate into bone and/or cartilage. This capacity is called osteochondrogenic potential. In this study, preconfluent MSCs were exposed in vitro to 5 ng/ml transforming growth factor-beta 1 (TGF-beta 1) or platelet-derived growth factor, isoform BB (PDGF-BB) for a pulse of 48 h and assayed for cell proliferation, alkaline phosphatase activity, and osteochondrogenic potential; untreated MSC's served as controls. In these cell culture conditions, TGF-beta 1 or PDGF-BB had similar effects on proliferation and alkaline phosphatase activity. Both growth factors increased cell proliferation and decreased alkaline phosphatase activity of MSCs. Sister cultures of TGF-beta 1- or PDGF-BB-treated MSCs and untreated MSCs were trypsinized. For each type of culture, the trypsinised MSCs were split in two parts: one part was replated in an osteogenic medium to assess its in vitro osteogenic potential, whereas the other part was seeded into porous calcium phosphate ceramics and implanted subcutaneously in syngeneic rats to assess its in vivo osteochondrogenic potential. PDGF-pretreated MSCs showed no difference in in vivo and in vitro osteochondrogenesis from that of control MSCs, while TGF-beta 1 pretreatment blocked the osteochondrogenic potential of MSCs when assayed in vitro for bone nodule formation. However, when tested in vivo, TGF-beta 1-pretreated MSCs were able to form bone and cartilage. These data show that measurements of proliferation and alkaline phosphatase activity of preconfluent MSCs immediately after exposure to growth factor were not predictive of their subsequent osteochondrogenic potential. Moreover, the variation of the osteochondrogenic potential of MSCs after exposure to growth factor was further modulated by the environment in which the MSCs were assayed.

Pharmacokinetics and bioavailability of midazolam after intravenous, subcutaneous, intraperitoneal and oral administration under a chronic food-limited regimen: relating DRL performance to pharmacokinetics

The effects of midazolam on animal behavior often are evaluated under a chronically food-limited regimen, which is used to implement food-reinforced performance, but the corresponding pharmacokinetics are lacking. The present study investigated the pharmacokinetics of midazolam after i.v., s.c., i.p., and p.o. administration in food-limited rates. A two-compartment model best described the concentration-time profiles for the four routes of administration. The rate of midazolam absorption was rapid, and peak concentrations were attained in less than 7 min for the three extravascular routes. The mean volume of distribution of the central compartment and clearance were 0.77 l/kg and 2.03 l/h per keg, respectively. Midazolam elimination half-lives for the four routes of administration ranged from 23.1 to 49.5 min, and metabolites could not be detected. The mean absolute bioavailability was route-dependent: 39.3% (s.c.) 19.2% (i.p.) and 4.6% (p.o.). The markedly low oral bioavailability found in food-limited rats contrasted to the value reported for free-feeding rates (45%). Although the i.p. route yielded the highest maximum concentration on occasion, serum midazolam concentration-time profiles were variable, but did correspond to respective sedative responses. DRL 45-s performance after s.c., i.p., and p.o. administration further supported the advisability of using the s.c. route of administration, as opposed to the i.p. route, for studying midazolam dose-response relations. The bioavailability values assessed from DRL performance also agree with the measured pharmacokinetic values.

Determination of midazolam and its metabolites in serum microsamples by high-performance liquid chromatography and its application to pharmacokinetics in rats

A single-solvent extraction step high-performance liquid chromatographic method is described for quantitating midazolam and its two hydroxy metabolites in rat serum microsamples (50 microliters). The separation used a 2 mm I.D. reversed-phase Symmetry C18 column with an isocratic mobile phase consisting of methanol-acetonitrile-14.9 mM sodium acetate in water at pH 3.0 (10:23:67, v/v). The detection limit was 10 ng/ml for all the compounds using an ultraviolet detector operated at 230 nm. The method was used to study the pharmacokinetics of midazolam after an intravenous bolus dose (0.75 mg/kg).

Induction of osteogenesis by bovine platelet transforming growth factor-beta (TGF-beta) in adult mouse femur

TGF-beta has been shown to be one of the most important regulators in chondrogenesis and osteogenesis. Daily subperiosteal injection of TGF-beta, which was extracted and purified from bovine platelets, into adult mouse femur resulted in proliferation and differentiation of the mesenchymal cells, chondrogenesis, and endochondral osteogenesis. After cessation of the injection, the endochondral ossification occurred widely, resulting in replacement of the cartilage with new bone. These phenomena demonstrate that exogenous TGF-beta stimulates mesenchymal proliferation and differentiation that occur in early fracture healing and suggest the possibility of clinical application of TGF-beta for fracture repair and bone transplantation.

[An epidemiologic study on pulmonary fibrosis caused by hard alloy dust]

A cross-sectional study, with 1,237 employees solely exposed to hard alloy dust and 502 controls in four hard metal works and two tool and grinder manufacturers in China, was conducted. Results showed prevalence of symptoms of respiratory system, and abnormalities in lung function and serum level of ceruloplasmin and urine cobalt content in exposed group were significantly higher than those in controls. Eight cases of pneumoconiosis were detected by chest X-ray films with a prevalence of 0.65% and an average length of employment in dust environment of 25.2 years. It suggested hard alloy dust could cause pulmonary fibrosis and pneumoconiosis in exposed workers.