Dose independent pharmacokinetics of caffeine after intravenous administration under a chronic food-limited regimen

Several studies have shown that caffeine follows non-linear pharmacokinetics in both rats and humans. Recent data have demonstrated that caffeine may following linear pharmacokinetics when administered orally and intraperitoneally to food-limited rats. In this study the pharmacokinetics of caffeine was analyzed following intravenous (i.v.) administration to rats under a food-limited regimen. Four rats were administered four doses of caffeine and a standard dose of the caffeine metabolites, paraxanthine, theobromine, and theophylline. Caffeine pharmacokinetic parameters were dose independent following intravenous doses ranging from 1 to 20 mg/kg. Furthermore, the caffeine area under the curve (AUC) increased linearly as a function of dose. The mean fraction of caffeine converted to paraxanthine, theobromine, and theophylline was 16%, 16%, and 7%, respectively. The linear pharmacokinetics demonstrated in the present study may be attributed to the induction of hepatic metabolism under a chronic food-limited regimen.

Incorporation of the waveguide feed and cavity wall losses into a cartesian/cylindrical hybrid finite-difference time domain analysis of a geometrically-composite microwave applicator

A Surface-Impedance Boundary Condition (SIBC) formulation is combined for the first time with a Cartesian/cylindrical hybrid Finite-Difference Time Domain (FD-TD) algorithm to investigate the effects on the electromagnetic characterization of a geometrically-composite microwave heating applicator introduced by the finite conductivity of the waveguide feed and cavity walls. The computational accuracy of the proposed scheme is validated in terms of the energy balance principle. Computer simulations revealed that the inclusion of wall losses has negligible effects on the interior field distribution and the reflection coefficient, S11. Finally, the formulation developed in this paper can be employed in estimating the wall losses of other microwave-applicator systems with similar surface characteristics.

[6A8 cDNA encodes A type of alpha-mannosidase]

OBJECTIVE

To find the nature of the protein encoded by 6A8 cDNA.

METHODS

In the light of that the ligand of Con A is mannoses and that the function of alpha-mannosidase is trimming of mannoses in the oligosaccharide chains of glycoproteins, COS-7 cells and CNE-2L2 cells, a cloned cell line of human nasopharyngeal carcinoma, were transfected with pRc/CMV-sense 6A8 cDNA or pRc/CMV-antisense 6A8 cDNA and the Con A binding to the cells was examined upon a lazer scan confocal microscope.

RESULTS

The data demonstrated that with transfection of pRc/CMV-sense 6A8 cDNA the binding of Con A to the cells was decreased, but the staining of the cells with mAb 6A8 was enhanced, and vise versa for the cells with transfection of pRc/CMV-antisense 6A8 cDNA.

CONCLUSIONS

The protein encoded by 6A8 cDNA might be a type of alpha-mannosidase recognized by mAb 6A8.

Sociodemographic correlates of visual acuity impairment in Hispanic children and adolescents

Sociodemographic correlates of visual impairment were examined in 6- to 19-year-old Hispanic children and adolescents using data from the Hispanic Health and Nutrition Examination Survey. Mexican American and Puerto Rican children whose parents had 0 to 6 years of education were more likely to remain visually impaired even when tested with their glasses or contact lenses, if any (i.e., with usual correction) than children whose parents reported 12 to 17 years of education. Mexican Americans residing below versus at or above the poverty line were more likely to remain visually impaired even with the usual correction. Mexican Americans enrolled in the Medicaid program or who were without health insurance were more likely to remain visually impaired than Mexican Americans with private health insurance. When tested without glasses or contact lenses, Cuban Americans and Mexican Americans born outside of the mainland United States had lower rates of visual impairment compared to those born in the United States; however, children in this latter group were more likely to remain visually impaired with usual correction than U.S.-born Mexican Americans. These findings suggest that Hispanic children from economically disadvantaged households and those born outside the United States may not be receiving optimal eye care that could improve visual function.

Expression of stromal cell-derived factor-1/pre-B cell growth-stimulating factor receptor, CXC chemokine receptor 4, on CD34+ human bone marrow cells is a phenotypic alteration for committed lymphoid progenitors

We found that the stromal cell-derived factor-1/pre-B cell growth-stimulating factor receptor, CXC chemokine receptor 4 (CXCR4), is expressed on human CD34+ bone marrow (BM) cells. Stringently FACS-sorted CD34+CXCR4+ BM cells completely lack myeloid, erythroid, megakaryocytic, and mixed colony-forming potential (myeloid progenitors), but give rise to B and T lymphoid progenitors, whereas CD34+CXCR4- BM cells can generate colonies formed by myeloid progenitors and can also develop into these lymphoid progenitors. Therefore, expression of CXCR4 on CD34+ BM cells can allow lymphoid progenitors to be discriminated from myeloid progenitors. Because CD34+CXCR4+ cells are differentiated from CD34+CXCR4- cells, multipotential progenitors located in the BM are likely to be negative for CXCR4 expression. CXCR4 seems to be expressed earlier than the IL-7R and terminal deoxynucleotidyl transferase during early lymphohemopoiesis. These results suggest that the expression of CXCR4 on CD34+ BM cells is one of the phenotypic alterations for committed lymphoid progenitors.

Cocaine pharmacodynamics after intravenous and oral administration in rats: relation to pharmacokinetics

RATIONALE

To design optimal dose regimes for oral cocaine, it is essential to characterize pharmacokinetics (PK) of cocaine after IV and PO administration.

OBJECTIVES

To investigate the absolute bioavailability of oral cocaine, its effectiveness and the relation between PK and PD in a within-subject design.

METHODS

We used the effects of IV and PO cocaine on a contingency-controlled timing behavior, the differential reinforcement of low rate schedule (DRL 45-s) in 3-h sessions, as the PD measures [i.e., the shorter-response rate (srr) and the reinforcement rate (rr)]. Cocaine PK parameters were determined by simultaneous modeling of the concentration-time profiles (CTPs) after IV 2 mg/kg and PO 20 mg/kg cocaine administration. The absolute oral cocaine bioavailability was determined pharmacokinetically (F) and pharmacodynamically (Fsrr and Frr).

RESULTS

IV and PO cocaine increased the shorter response rate and decreased the reinforcement rate in a dose- and time-related fashion, which mirrored the respective prototypical serum cocaine CTPs. After the absorption phase, the serum cocaine CTP of PO cocaine paralleled that of IV cocaine. The duration of action for PO cocaine was longer than that for IV cocaine owing to its larger mean residence time. The active metabolite, norcocaine, was not detected after IV but after PO cocaine administration. The value of F was 4.66% which was significantly lower than the values of Fsrr (13.67%) and Frr (32.63%). Furthermore, the concentration-effect relations for the reinforcement rate revealed that PO cocaine was more potent than IV cocaine.

CONCLUSIONS

Oral cocaine is more effective behaviorally than from predictions made in terms of its PK. The differences in active metabolite profiles as well as the rate and extent of acute tolerance for IV versus PO cocaine may account for the greater potency observed for oral cocaine.

[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.

Oral and IP caffeine pharmacokinetics under a chronic food-limitation condition

For food-limited rats, serum caffeine was proportional to IP caffeine doses (10-40 mg/kg) for Cmax and area under the curve [AUC(0-24 h)], whereas the three dimethylxanthine (DMX) metabolites of caffeine were disproportional over the dose range. Steady-state concentrations of caffeine and the three metabolites were evident at the 11th day of chronic, daily caffeine IP 20 mg/kg doses. Both caffeine and the three metabolites were dose proportional for Cmax and AUC(0-24 h) by schedule-induced oral caffeine self-administration within the dose range taken (9-38 mg/kg). These results contrast with the nonlinear kinetics of caffeine reported for rats under ad lib conditions. Elimination rate constants (Kel) remained the same for the two routes, but apparent volume of distribution (AVd) and clearance (Cl) were different. The order of the Kel values was caffeine > paraxanthine > theophylline > theobromine. The effects of linear vs. nonlinear caffeine pharmacokinetics may have distinct implications for the resulting pharmacodynamics.

Interferon-gamma inhibits proliferation, but not commitment, of murine granulocyte-macrophage progenitors

We investigated the effects of interferon gamma (IFN-gamma) on the growth of murine hematopoietic progenitors. IFN-gamma inhibited granulocyte colony-stimulating factor (G-CSF)- and interleukin-3 (IL-3)-dependent colony growth by granulocyte-macrophage (GM) progenitors derived from the bone marrow cells of normal mice. However, the number of IL-3-dependent GM colonies formed by the bone marrow cells of 5-fluorouracil (5-FU)-treated mice was not influenced by the addition of IFN-gamma. Replating experiments suggested that IFN-gamma suppressed GM colony growth directly and that it exerted an inhibitory effect on the proliferation, but not on the commitment, of GM progenitors. In contrast, IFN-gamma failed to suppress colony growth by mast cell progenitors. Erythroid and megakaryocytic progenitors exhibited different responses to IFN-gamma depending on mouse strains. These results suggest that potent negative regulators are not always inhibitors of hematopoietic progenitors.

[Effect of CCK receptor antagonists on plasma CCK bioassay]

Fasting and postprandial plasma CCK levels of 102 normal subjects were measured by bioassay with dispersed rat pancreatic acini. The reference values ranged from 0 to 4.2 pmol/L (CCK-8 equivalents) for fasting and from 1.1 to 13.5 pmol/L for postprandial state. There was no significant difference between male and female, or in different age groups. The effects of CCK receptor antagonists of 3 different categories on CCK bioactivity in plasma measured by the bioassay were investigated. L 364,718 (5 nmol/L), proglumide (1.0 mmol/L), or Bt2-cGMP (0.1 mmol/L) was either extracted by SEP-PAK C18 cartridges together with human plasma containing 8 pmol/L of CCK-8, or added into the plasma extracts before the assay. The CCK bioactivity was inhibited by all of the 3 CCK antagonists. The action of L364,718 could be eliminated by the procedure of plasma extraction, but not of proglumide or Bt2-cGMP. It was suggested that CCK bioassay can be used even if L364,718 was administered. However, CCK cannot be measured accurately if there are proglumide or Bt2-cGMP in the plasma.

[Pharmacological study on anti-hepatitis effect of Cotinus coggygria Scop. Syrup]

This paper shows that the Cotinus coggygria syrup has the effect of protecting the liver from chemical damages, reducing tension of the choledochal sphincter, increasing the bile flow and raising the body immunity. The anti-hepatitis effect may be carried out through decreasing transaminase, normalizing functioning of the gallbladder, reducing icterus and enhancing the immunity of the body.

Chronic oral cocaine self-administration: pharmacokinetics and effects on spontaneous and discriminative motor functions

Rats receiving repeated doses of oral cocaine (15 mg/kg) showed replicable increases in large-movement and small-movement activity rates, but sensitization to the repeated doses did not develop. With a schedule-induction procedure, as the daily, 3-hr, oral dose of self-administered cocaine increased, marked dose-related increases occurred in both large-movement locomotor activity rate and the time for which these elevations were sustained during the following daily 2-hr activity session. Sensitization developed. At the highest levels of self-administered oral cocaine (about 80 mg/kg), post-administration serum cocaine levels remained undiminished for the activity-session period, as did the large-movement activities of most animals, indicating no development of acute tolerance. Rats receiving repeated doses of oral cocaine (15 mg/kg) showed discriminative motor control deficits as well as increases in work rate. These changes were dose-related in animals self-administering oral cocaine under the schedule-induction procedure. Upon withdrawal of cocaine from the schedule-induction animals, motor behavior returned to precocaine base-line performance for most animals. The behavior of the animal with the largest cocaine intake did not return. After a schedule-induced oral cocaine intake session, the tail-tip and trunk serum measures for cocaine and its metabolites were approximately equivalent, while brain cocaine and norcocaine levels remained markedly elevated over serum values.

Acute effects of cocaine on spontaneous and discriminative motor functions: relation to route of administration and pharmacokinetics

Rats administered cocaine i.p. and p.o. (7.5-30 mg/kg) showed dose-related increases in locomotor (LM) and small-movement activities, with LM rates decreasing over the 2-hr session, except at the largest i.p. dose, for which rates were greater in the 2nd hr. Lidocaine p.o. (15-30 mg/kg) did not increase activity. Relating the area under the curve measures for serum cocaine (concentration-time) and LM activity (LM activity-time) for 2 hr postadministration indicated that cocaine was about twice as potent i.p., compared to p.o., in increasing LM activity. Cocaine (i.p. and p.o.) produced dose-related decrements in both discriminative motor control performance and in task work rate, whereas lidocaine p.o. did not. The motor control decrements produced by cocaine were approximately comparable by i.p. and p.o. routes, whereas effects on LM rates were much greater by i.p. than by p.o. administration. The effects of cocaine by both routes on LM rates were proportionally much greater than its effect on motor control performance. Changes in LM rates and motor control performance over the postadministration period were related to the pharmacokinetic features (maximum serum concentration, time to maximum serum concentration and elimination half-life) of cocaine observed for the routes explored (i.p., p.o. and s.c.). Tail-tip serum samples, although yielding conservative estimates of cocaine concentration, correlated well with trunk serum and brain cocaine levels.

Simultaneous determination of cocaine and its metabolites with caffeine in rat serum microsamples by high-performance liquid chromatography

A single, isocratic high-performance liquid chromatographic method is described for the determination of cocaine and three of its metabolites along with caffeine in serum microsamples (50 microliters). The small sample size permits the tracking of pharmacokinetic data over time in individual, small animals. The method also was used to demonstrate that cocaine, benzoylecgonine and norcocaine in rat serum samples were stable for at least a month without the presence of sodium fluoride.

Effect of low fat-high carbohydrate diets in hypertensive patients with non-insulin-dependent diabetes mellitus

Effects of variations in dietary fat and carbohydrate content on various aspects of glucose, insulin, and lipoprotein metabolism were evaluated in 11 patients with hypertension, who also had non-insulin-dependent diabetes mellitus (NIDDM). All of these patients were being treated with sulfonylureas, thiazides, and beta-adrenergic receptor antagonists. The comparison diets contained either 40 or 60% of total calories as carbohydrate, with reciprocal changes in fat content from 40 to 20%. The diets were consumed in a random order for 15 days in a crossover experimental design. The ratio of polyunsaturated to saturated fat and total cholesterol intake were held constant in the two diets. Plasma glucose and insulin concentrations were significantly (P less than .001) elevated throughout the day when patients consumed the 60% carbohydrate diet. Fasting plasma total and very-low-density lipoprotein (VLDL) and triglyceride (TG) concentrations increased by 30% (P less than .001) after 15 days on the 60% carbohydrate diet. Total plasma cholesterol concentrations were similar on both diets, as were low-density lipoprotein (LDL) and high-density lipoprotein (HDL) cholesterol concentrations.

Regional hyperthermia combined with blockade of the hepatic arterial blood flow by degradable starch microspheres in pigs

The benefit of hepatic arterial microembolization by degradable starch microspheres (DSM) was investigated in regional hyperthermia of the liver. Hyperthermia with and without blood flow blockade of the hepatic artery using degradable starch microspheres was performed on six pigs. Heat was given for 30 min in each treatment by 8 MHz radiofrequency capacitive heating equipment. To maintain blood flow blockade during hyperthermia, 10 mg/kg of degradable starch microspheres was administered into the hepatic artery as an initial dose and 5 mg/kg of the drug was added periodically under the measurement of hepatic arterial blood flow by an electromagnetic flowmeter. To evaluate the effect of degradable starch microspheres, the temperature increase in the liver and rectum was compared between the treatment with and without DSM. All pigs showed a larger increase in intrahepatic temperature when heated in combination with degradable starch microspheres than without. On the other hand, temperature increase in the rectum as a result of hyperthermia to the liver was suppressed by DSM as compared with hyperthermia alone. These results indicate that hepatic arterial embolization by degradable starch microspheres potentiates radiofrequency capacitive heating of the liver. Although this study was not made with liver tumors, regional hyperthermia may be effective in the control of liver tumors when heat is given after the blockade of the hepatic artery by DSM.

Microencapsulated hepatocytes: an in vitro and in vivo study

Using a modified alginate-polylysine membrane, we have successfully encapsulated rat hepatocytes with little loss of viability. Urea and albumin release from encapsulated liver cells was comparable to that from non-encapsulated cells during the first 4 days in culture. Histological studies also showed that more than 50% of the encapsulated hepatocytes remained viable 35 days after implantation in the peritoneal cavity of both normal rats and rats with galactosamine induced fulminant hepatic failure. Transplantation of microencapsulated hepatocytes provides a potential clinical treatment for liver failure.

Induction of polyphosphoinositide breakdown in rat corpus luteum by prostaglandin F2 alpha

The present study examines the possibility that, in the rat corpus luteum, an initial action of prostaglandin F2 alpha (PGF2 alpha) is to induce a ligand-stimulated breakdown of membrane inositol phospholipids. Luteal cells in primary culture were prepared from immature rats after PMSG and human CG priming. In 32P-prelabeled cells, PGF2 alpha caused a rapid decrease in the level of radiolabel found in phosphatidylinositol 4-phosphate and phosphatidylinositol 4,5-bisphosphate, as early as 20 sec after addition of the hormones. At 1 and 2.5 min, the effect of 10(-6) M PGF2 alpha on phosphatidylinositol 4,5-bisphosphate was significantly greater than that caused by 10(-6) M LHRH in identical cell cultures. By contrast, the levels of the 32P-prelabeled phosphatidylinositol and phosphatidic acid were increased at 5 min by PGF2 alpha or LHRH. Concomitant with the alterations in cellular levels of 32P-prelabeled phospholipids, PGF2 alpha markedly enhanced the accumulation of 3H-labeled inositol phosphates, i.e. inositol 1-phosphate, inositol diphosphate, and inositol triphosphate, during a 5-min incubation. A significant increase of radiolabeled inositol diphosphate was seen as early as 1 min after the addition of either PGF2 alpha or LHRH; PGF2 alpha was more effective than LHRH in this regard. The stimulatory effect of LHRH on inositol phosphate accumulation could be blocked completely by the concomitant presence of a potent LHRH antagonist, and at the concentration used (10(-6) M) the effects of PGF2 alpha and LHRH were not additive. Interestingly, the addition of an exogenous phospholipase C also caused a similar enhancement of inositol phosphate accumulation in identical cell cultures. For the first time, these data suggest that, at the level of the corpus luteum, hydrolysis of phosphoinositides may immediately follow PGF2 alpha (and to a lesser extent LHRH) receptor binding, and this in turn may lead to the generation of 1,2-diacylglycerol and inositol phosphates, resynthesis of phosphatidic acid and phosphatidylinositol, and mobilization of Ca2+.

Response of mammary tumors of C3H/He mice to hyperthermia and bleomycin in vivo

The cytotoxicity of bleomycin in vitro has previously been shown to be enhanced by hyperthermia. This study demonstrates in vivo a synergistic interaction between local hyperthermia (43 degrees C, 45 min) and bleomycin (15 mg/kg) against implanted mammary tumors of C3H/He mice. Hyperthermia was given by water bath heating. When combined treatments of heat and bleomycin were administered within 30 min of each other, a synergistic effect was observed. In contrast, when the interval between heat and bleomycin injection was longer than 30 min, only an additive effect was obtained. Timing is therefore considered to be a critical factor for the optimal combination of hyperthermia and bleomycin.

Luteinizing hormone-releasing hormone enhances polyphosphoinositide breakdown in rat granulosa cells

A 2-min addition of LHRH to [3H]inositol-prelabeled rat granulosa cells in primary culture evoked significant increases in the accumulation of [3H]inositol phosphates, i.e. radiolabeled inositol monophosphate (IP), inositol diphosphate (IP2), and inositol triphosphate (IP3) levels increased to 210, 590 and 520%, respectively, when compared to control cultures. By contrast, addition of FSH failed to elicit such a response. The effect of LHRH was completely blocked by the concomitant presence of a specific LHRH antagonist. LHRH evoked increase in [3H]IP3 and [3H]IP2 accumulation as early as 30 sec, while the increase in [3H]IP became significant at 2 min. These data support the hypothesis that polyphosphoinositide breakdown may be an early step in the intracellular signal mechanism which mediates the action of LHRH.