Emerging and Fastidious Uropathogens Were Detected by M-PCR with Similar Prevalence and Cell Density in Catheter and Midstream Voided Urine Indicating the Importance of These Microbes in Causing UTIs

Introduction

This study compared microbial compositions of midstream and catheter urine specimens from patients with suspected complicated urinary tract infections to determine if emerging and fastidious uropathogens are infecting the bladder or are contaminants.

Methods

Urine was collected by in-and-out catheter (n = 1000) or midstream voiding (n = 1000) from 2000 adult patients (≥60 years of age) at 17 DispatchHealth sites across 11 states. The two groups were matched by age (mean 81 years), sex (62.1% female, 37.9% male), and ICD-10-CM codes. Microbial detection was performed with multiplex polymerase chain reaction (M-PCR) with a threshold for "positive detection" ≥ 10,000 cells/mL for bacteria or any detection for yeast. Results were divided by sex.

Results

In females, 28 of 30 microorganisms/groups were found by both collection methods, while in males 26 of 30 were found by both. There were significant overlaps in the detection and densities of classical uropathogens including Escherichia coli, Enterococcus faecalis, and Klebsiella pneumoniae, as well as emerging uropathogens including Actinotignum schaalii and Aerococcus urinae. In females, detection rates were slightly higher in midstream voided compared to catheter-collected (p = 0.0005) urine samples, while males showed the opposite trend (p < 0.0001). More polymicrobial infections were detected in midstream voided compared to catheter-collected samples (64.4% vs 45.7%, p < 0.0001) in females but the opposite in males (35.6% vs 47.0%, p = 0.002).

Discussion

In-and-out catheter-collected and midstream voided urine specimens shared significant similarities in microbial detections by M-PCR, with some differences found for a small subset of organisms and between sexes.

Conclusion

Non-invasive midstream voided collection of urine specimens for microbial detection and identification in cases of presumed UTI does not result in significantly more contamination compared to in-and-out catheter-collected specimens. Additionally, organisms long regarded as contaminants should be reconsidered as potential uropathogens.

Pharmacokinetics of doxycycline in broiler chickens

Doxycycline was given to two groups of eight chickens at a dose of 20 mg/kg of body weight, intravenously (i.v.) or orally. Plasma concentration was monitored serially for 12 h after each administration. Another group of 30 chickens was given 20 mg/kg orally every 24 h for 4 days, and plasma and tissue concentrations determined serially after the last administration. Concentrations of doxycycline were measured using high-performance liquid chromatography. Pharmacokinetic variables were calculated, using a two-compartment open model. The elimination half-life and the mean residence time for plasma were 6.03 +/- 0.45 and 7.48 +/- 0.38 h, respectively, after oral administration and 4.75 +/-0.21 and 2.87 +/-0.11 h, respectively, after i.v. administration. After single oral administration, doxycycline was absorbed rapidly, with T(max) of 0.35 +/- 0.02 h. Maximum plasma concentration was 54.58 +/- 2.44 mu/ml. Oral bioavailability of doxycycline was found to be 41.33 +/- 2.02%. Doxycycline was widely distributed in tissues and considerable concentrations were found following oral administration of 20 mg/kg on four successive days. The results indicate that doxycycline concentrations were cleared slowly and were at or below the accepted drug tolerance levels in the marker tissues within 5 days after dosing.

Toxicokinetics and oral bioavailability of fumonisin B1

The kinetics of fumonisin B1 (FB1) after single doses of 10 mg FB1/kg (po) or 2 mg FB1/kg (i.v.) were studied in male Wistar rats. Serial blood samples were obtained after p.o and i.v. administration. Liver and kidney tissue samples were also obtained after p.o administration. Plasma, liver and kidney concentrations of FB1 were determined by a reversed-phase high-performance liquid chromatographic assay using precolumn 0-phthaldialdehyde derivatisation with fluorescence detection. The FB1 plasma profile could be adequately described by a 2-compartment open model. For FB1, the elimination half-life from plasma was 1.03 h after i.v. and 3.15 h after p.o administration. The apparent volume of distribution and volume of distribution at steady state for FB1 were 0.11 and 0.072 L, respectively, after i.v. administration. The total plasma clearance of FB1 was the same for both the p.o and i.v. routes, 0.072 L/h. After the single p.o dose, FB1 was rapidly absorbed with a Tmax of 1.02 h. The maximum plasma concentration of FB1 was 0.18 microgram/mL. The p.o bioavailability of FB1 was 3.5%. The tissue concentration time data for FB1 fit a 1-compartment open model. Considerable concentrations of FB1 were found in the liver and kidney tissues. The elimination half-lives for FB1 were longer for liver (4.07 h) and kidney (7.07 h) than for plasma (3.15 h). Tissue accumulation of FB1 was evidenced by the tissue/plasma area under the concentration-time curve (AUC) ratios; the AUCtissue/AUCplasma for FB1 was 2.03 in liver and 29.89 in kidney.

Induction of cytochrome P4501A1 and P4504A1 activities and peroxisomal proliferation by fumonisin B1

The effects of repeated exposure to fumonisin B1 (FB1) on hepatic and renal mixed function oxidase activities and peroxisomal proliferation has been examined in rats following intraperitoneal administration at three dose levels (0.125, 0.25, and 2.5 mg/kg) once a day for 6 days. At the two highest doses, FB1 increased the renal and hepatic N-demethylation of erythromycin (CYP3A1) and the hepatic O-deethylation of ethoxyresorufin (CYP1A1). FB1, at the highest dose of 2.5 mg/kg, also increased the renal O-deethylation of ethoxyresorufin. The liver, but not the kidney, was also susceptible to FB1-dependent induction of the 12- and 11-hydroxylation of lauric acid, suggesting induction of the CYP4A subfamily. Immunoblot studies employing solubilized microsomes from FB1-treated rats revealed that FB1, at the two highest doses, increased the apoprotein levels of CYP1A1 and CYP4A1. The same treatment with FB1 increased the beta-oxidation of palmitoyl-coenzyme A (CoA) in liver homogenates, and immunoblot analysis showed an increase in the apoprotein levels of the trans-2-enoyl-CoA hydratase trifunctional protein. The possible implications of these findings to the hepatocarcinogenicity of this mycotoxin are discussed.

Toxicokinetics of deltamethrin and its 4'-HO-metabolite in the rat

The toxicokinetics of deltamethrin and its metabolite 4'-HO-deltamethrin after single doses of 26 mg of deltamethrin/kg (oral) or 1.2 mg of deltamethrin/kg (intravenous) were studied in male Wistar rats. Serial blood samples were obtained after oral and intravenous administration. Brain, vas deferens, and anococcygeus tissue samples were also obtained after oral administration. Plasma, hypothalamus, cerebellum, frontal cortex, caudate putamen, hippocampus, medulla oblongata, vas deferens, and anococcygeus concentrations of deltamethrin and 4'-HO-deltamethrin were determined by a high-performance liquid chromatographic assay. The deltamethrin and 4'-HO-deltamethrin plasma profiles could be adequately described by a two-compartment open model. For deltamethrin and 4'-HO-deltamethrin, the elimination half-lives (t1/2 theta) from plasma were 33.0 and 25.67 hr after iv and 38.50 and 30.13 hr after po administration of deltamethrin parent compound. The apparent volume of distribution [V alpha(area)] and volume of distribution at steady state [V d(m)] for deltamethrin were 5.33 and 2.04 liters, respectively, after iv administration, suggesting a considerable diffusion of the pyrethroid into tissue. The total plasma clearance of deltamethrin was the same for both the oral and the iv routes-0.11 liter/hr. After the single oral dose, deltamethrin was rapidly absorbed with a Tmax of 1.83 hr. The maximum plasma concentrations of deltamethrin and 4'-HO-deltamethrin were 0.46 and 0.26 microgram/ml. The maximum plasma concentration of 4'-HO-deltamethrin was achieved at 3.29 hr. The oral bioavailability of deltamethrin was found to be 14.43%. The tissue concentration time data for deltamethrin and its metabolite 4'-HO-deltamethrin were found to fit a one-compartment open model. Considerable concentrations of deltamethrin and 4'-HO-deltamethrin were found in the hypothalamus, cerebellum, frontal cortex, caudate putamen, hippocampus, medulla oblongata, vas deferens, and anococcygeus tissues. The elimination half-lives (t1/2 el) for both deltamethrin and 4'-HO-deltamethrin were somewhat smaller for the cerebellum, frontal cortex, caudate putamen, medulla oblongata, vas deferens, and anococcygeus tissues (range, 18-33 hr for deltamethrin and 15-28 hr for 4'-HO-deltamethrin) than for plasma (t1/2 el, 38.50 and 30.13 hr, respectively). Exceptions were seen for the hypothalamus and hippocampus in which the t1/2et's for deltamethrin were 40.76 and 38.50 hr, respectively. Nervous tissue accumulation of deltamethrin and its metabolite 4'-HO-deltamethrin was evidenced by the tissue/plasma area under the concentration (AUC) versus time curve ratios. The ratios of AUCtissue/AUCplasma for deltamethrin were 2.32 in medulla oblongata, 295.30 in hypothalamus, and intermediate in other tissues.

Pharmacokinetics and tissue residues of norfloxacin and its N-desethyl- and oxo-metabolites in healthy pigs

The pharmacokinetic properties of norfloxacin were determined in healthy pigs after single intramuscular (i.m.) and intravenous (i.v.) dosage of 8 mg/kg body weight. After i.m. and i.v. administration, the plasma concentration-time graph was characteristic of a two-compartment open model. After single i.m. administration, norfloxacin was absorbed rapidly, with a tmax of 1.46 +/- 0.06 h. The elimination half-life (t1/2 beta) and the mean residence time of norfloxacin in plasma were 4.99 +/- 0.28 and 6.05 +/- 0.22 h, respectively, after i.m. administration and 3.65 +/- 0.16 and 3.34 +/- 0.16 h, respectively, after i.v. administration. Intramuscular bioavailability was found to be 53.7 +/- 4.4%. Plasma concentrations greater than 0.2 microgram/mL were achieved at 20 min and persisted up to 8 h post-administration. Maximal plasma concentration was 1.11 +/- 0.03 micrograms/mL. Statistically significant differences between the two routes of administration were found for the half-lives of both distribution and elimination phases (t1/2 alpha, t1/2 beta) and apparent volume of distribution (Vd(area)). In pigs, norfloxacin was mainly converted to desethylenenorfloxacin and oxonorfloxacin. Considerable tissue concentrations of norfloxacin, desethylenenorfloxacin, and oxonorfloxacin were found when norfloxacin was administered intramuscularly (8 mg/kg on 4 consecutive days). The concentration of the parent fluoroquinolone in liver and kidney ranged between 0.015 and 0.017 microgram/g on day 12 after the end of dosing.

Effects of flumethrin on hepatic drug-metabolizing enzymes and antipyrine disposition in rats

The effects of repeated exposure to the pyrethroid insecticide flumethrin (40 mg/kg intraperitoneally once a day for 6 days) on the activity of cytochrome P450-dependent monooxygenases and UDP-glucuronosyltransferase as well as on antipyrine disposition were investigated in male Wistar rats. Pretreatment with flumethrin decreased the activities of NADPH-cytochrome c reductase (38%), aniline hydroxylase (53%), aminopyrine N-demethylase (54%), and UDP-glucuronosyltransferase (34%), and the content of cytochrome P450 (36%) in hepatic microsomes. Total plasma clearance of antipyrine was decreased by flumethrin pretreatment (54%), while the elimination half-life at beta phase and the mean residence time of antipyrine were increased (96 and 88%, respectively). Urinary excretion of norantipyrine, 4-hydroxyantipyrine, and 3-hydroxymethylantipyrine was decreased by 60, 38, and 33%, respectively, in the 96 hr after flumethrin treatment. In addition, the rate constants for formation of each of these metabolites were decreased by an average of approximately 74%. These findings provide evidence that flumethrin exposure diminishes hepatic enzyme levels and catalytic activities of monooxygenase systems as well as oxidative metabolism of antipyrine.

Bioavailability, pharmacokinetics and residues of chloramphenicol in the chicken

The pharmacokinetic properties of chloramphenicol were determined in broiler chickens after two single oral doses (30 and 50 mg/kg body weight) and after a single intravenous (i.v.) dose (30 mg/kg body weight). After oral and i.v. administration, the plasma concentration-time graph was characteristic of a two-compartment open model. After oral administration (30 and 50 mg/kg), chloramphenicol was absorbed rapidly (time to maximal concentration of 0.72 or 0.60 h) and eliminated with a mean half-life (t1/2 beta) of 6.87 or 7.41 h, respectively. The bioavailability was 29% at 30 mg/kg chloramphenicol and 38% at 50 mg/kg chloramphenicol. Concentrations greater than 5 micrograms/ml were achieved at 15 min and persisted up to 2 or 4 h post-administration, respectively. Statistically significant differences between the two routes of administration were found for the pharmacokinetic variables, half-lives of both distribution and elimination phases (t1/2 alpha, t1/2 beta) and apparent volume of distribution [Vd(area)]. The mean t1/2 beta of chloramphenicol and i.v. administration was 5.23 h. Chloramphenicol was extensively metabolized into dehydrochloramphenicol (DH-CAP), nitrophenylaminopropanedione (NPAP) and nitroso-chloramphenicol (NO-CAP) derivatives. Residues of chloramphenicol (CAP) and the three metabolites DH-CAP, NPAP and NO-CAP in kidney, liver and muscle were measured in chickens that received an oral dose of 50 mg/kg once daily for 4 days. The results indicate that CAP and DH-CAP residues were cleared slowly and were at or below the detection limit of 0.005 microgram/ml within 12 days after dosing. However, at the time of slaughter (12 days), the NPAP and NO-CAP residues were detected in the tissue.

Induction of cytochrome P4504A by the peroxisome proliferator perfluoro-n-octanoic acid

The influence of a single dose of the peroxisome proliferator, perfluoro-n-octanoic acid (PFOA) on hepatic and renal mixed-function oxidase activities has been examined in rats. Peroxisome proliferation was confirmed by increases in peroxisomal palmitoyl-CoA oxidation and carnitine acetyl transferase activity, particularly in liver. The liver was also more susceptible than the kidney to PFOA-dependent induction of the 12-hydroxylation of lauric acid, suggesting induction of the CYP4A sub-family. This was further confirmed by Western blot analyses, wherein an anti-CYP4A1 antibody revealed a substantial PFOA-dependent induction of CYP4A1 in a pattern similar to that observed for the classical peroxisome proliferator, clofibrate. In addition, using a cDNA probe to CYP4A1 in Northern blot analysis, PFOA treatment resulted in a marked increase in the steady state level of CYP4A1 mRNA, again more extensively in liver than in kidney. Taken collectively, our data provide compelling evidence that PFOA, like other peroxisome proliferators, is also an inducer of the CYP4A subfamily.

Chlorotrifluoroethylene trimer and tetramer are inducers of the CYP4A subfamily

Male Wistar albino rats were treated for a 7 day period with equimolar doses of the trimer and tetramer oligomers of chlorotrifluoroethylene (CTFE), resulting in significant hepatomegaly for both compounds. In addition, both trimer and tetramer significantly induced the peroxisomal beta-oxidation of fatty acids as assessed by increases in palmitoyl-coenzyme A (CoA) oxidation, thus confirming these oligomers as peroxisome proliferators. Consistent with these conclusions, both trimer and tetramer increased the hydroxylation of lauric acid indicating that the CTFEs were inducers of the CYP4A subfamily, a conclusion further supported by substantial increases in the steady-state levels of the cognate CYP4A1 mRNA as determined by northern blotting. The liver appeared to be more susceptible to induction than the kidney and the CTFE tetramer was more potent than the trimer. These results are discussed with respect to both the differential hepatotoxicity, and biotransformation/disposition of the two polyhalogenated oligomers.

A 12-kilodalton N-glycosylated growth hormone-related peptide is present in human pituitary extracts

This study was designed to investigate whether N-linked glycosylation could account for the presence of glycosylated GH forms (G-GH) in human pituitary extracts. The study was carried out in commercially available pituitary GH preparations (pitGH). Recombinant GHs obtained from eu- or prokaryotic cells were used as controls. Radioiodinated GHs were incubated in tubes containing Concanavalin-A (Con-A) attached to a Sepharose 4B matrix. Pituitary G-GH forms were selectively displaced from Con-A by adding N-acetyl-D-glucosamine or methyl-alpha-D-mannopyranoside and electrophoresed. Autoradiographies of these gels identified a 12-kilodalton (12K) band as the glycosylated form. Due to the fact that this peptide was partially immunoprecipitated with an anti-GH serum and the absence of detectable PRL in the pitGH extracts, it would indicate that such a glycopeptide was GH related. Endoglycosidase-F treatment of pitGH extracts induced a decrease in the mol wt of that 12K peptide, as indicated by the changes observed in its mobility on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. This demonstrated that the sugar moieties were N-linked. When recombinant GHs were assayed by a similar method, no specific binding to Con-A was detected. NH2-terminal amino acid sequence analysis from the 12K band demonstrated that this band was composed by three peptides. Peptide 1 corresponds to the GH-N 102-119 sequence. Interestingly, peptide 2 exhibits GH-V 1-18 sequence, while peptide 3 seems to be a novel GH-related peptide. Taken together, these data suggest that the pituitary G-GH form found in human pituitary extracts is derived not from the "normal" GH-N gene, but, rather, from the GH-V gene or another unidentified gene. The potentially important pathophysiological implications of this finding need to be investigated.

Glucocorticoids may inhibit growth hormone release by enhancing beta-adrenergic responsiveness in hypothalamic somatostatin neurons

The aim of this study was to investigate the mechanisms by which glucocorticoids inhibit GH secretion in man. In 10 normal volunteers subjects we compared the pattern of GHRH-induced GH release to that elicited by similar challenge given 60 min after a pretreatment with drugs affecting adrenergic and muscarinic cholinergic neurotransmission, both in basal situations and after having induced hypercortisolism. In a first study (P), synthetic GHRH [GRF-(1-29); 1 microgram/kg, i.v.] was administered 60 min after giving placebo. In other experiments, the administration of propranolol (PRO; 40 mg, orally), or clonidine (CLO; 0.300 mg, orally), or pyridostigmine (PD; 120 mg, orally) was followed by GHRH administration 60 min later. These experiments were repeated after giving a nocturnal dose of dexamethasone (DEX; 8 mg, orally at 2300 h). The administration of DEX significantly (P < 0.05) blunted the GH response to GHRH (peaks: 10.7 +/- 3.9 vs. 20.3 +/- 5.5 micrograms/L; DEX vs. P study, respectively). Conversely, either beta-adrenergic blockade (PRO), or alpha 2-adrenergic agonism (CLO), or the enhancement of muscarinic cholinergic tone (PD) significantly increased the GH response to GHRH (peaks: 43 +/- 4.6, 55.6 +/- 5.6 and 51.2 +/- 7, micrograms/L; PRO, CLO, and PD, respectively; P < 0.01 vs. P study). After nocturnal DEX administration, both PRO and CLO, but not PD, were able to reverse the inhibitory effect of DEX on GHRH-elicited GH release (peaks: 39 +/- 5.5, 25.9 +/- 3.9 and 12.9 +/- 3.1, micrograms/L; DEX + PRO, DEX + CLO, and DEX + PD, respectively). However, whereas the potentiating effect of PRO on GHRH-elicited GH release was still observed under hypercortisolism, it was lacking for both CLO and PD when these drugs were given in this situation. These data suggest that the inhibitory effect of glucocorticoid excess on GH release is due to increased hypothalamic somatostatin secretion which appears to be dependent on DEX-induced enhanced beta-adrenergic responsiveness. Moreover, the data further support a major role of hypothalamic alpha 2-adrenergic and beta-adrenergic activities in GH neuroregulation in man.

Congenital gallbladder duplication: preoperative diagnosis by ultrasonography

Congenital gallbladder duplication, an uncommon but potentially complicating malformation, is rarely diagnosed preoperatively. A case in which the diagnosis was achieved by real-time ultrasonography is presented and correlated with hepatobiliary scintigraphy. The efficacy of these diagnostic modalities is discussed, and the available literature is reviewed.

Clonidine pretreatment modifies the growth hormone secretory pattern induced by short-term continuous GRF infusion in normal man

OBJECTIVE

The aim of this study was to investigate the effect of a single dose of clonidine on the pattern of GH release in response to a 10-hour continuous GRF infusion in normal man.

DESIGN

Plasma GH was analysed in samples withdrawn at 20-minute intervals, from 0900 to 1900 h, according to the following protocols: in a control study, a placebo was given at 1000 h; in other experiments, clonidine (300 micrograms, orally) was given at 1000 h, alone or together with a continuous intravenous infusion of GRF 1-29 (0.3 micrograms/kg/h) starting at this time. In another experiment, the continuous infusion of GRF 1-29 was preceded by placebo administration at 1000 h.

PATIENTS

Eight normal volunteers (four women and four men), aged 19-24 years were studied.

MEASUREMENTS

Plasma GH levels were measured by RIA. Analysis of the pattern of GH secretion was performed using cluster analysis.

RESULTS

Clonidine induced a slight but significant increase in plasma GH values, peaking 60 to 120 minutes later; however, no significant changes were observed in indices of total and pulsatile GH release for the whole sampling period in this study. Continuous GRF administration led to increased episodic GH secretion, by augmenting GH peak amplitude, although peak frequency was not modified. An increase in interpulse GH values was also observed during GRF infusion. Pretreatment with clonidine clearly changed the pattern of GH release during GRF infusion: the amount of GH secreted was significantly higher, the number of GH peaks significantly increased, and almost all the GH was secreted within them.

CONCLUSIONS

These data concord with our previous demonstration that clonidine disrupts the hypothalamic-somatotroph rhythm by inhibiting the hypothalamic release of somatostatin. Given that clonidine pretreatment induced a more physiological episodic pattern of GRF-induced GH release, the possibility of combining clonidine and GRF therapy for short stature in children is envisaged.

Toxicokinetics of permethrin in the rat

The toxicokinetics of permethrin after single 460 mg/kg oral and 46 mg/kg intravenous doses were studied in male Sprague-Dawley rats. Serial blood samples after oral and intravenous dosage, and brain, medulla oblongata, sciatic nerve, and liver samples after oral administration were collected. Plasma, hypothalamus, cerebellum, frontal cortex, caudate putamen, hippocampus, medulla oblongata, sciatic nerve, and liver concentrations of permethrin and its metabolites, m-phenoxybenzyl alcohol and m-phenoxybenzoic acid, were determined by a high-performance liquid chromatographic assay. The permethrin plasma profile could be adequately described by a two-compartment open model. For permethrin, the elimination half-life (t1/2 beta) and the mean residence time from plasma were 8.67 and 11.19 hr after i.v. and 12.37 and 17.77 hr after po administration. The total plasma clearance was not influenced by dose concentration or route and reached a value of 0.058 liter/hr. After the single oral dose, permethrin was absorbed slowly with a Tmax of 3.52 hr. The maximum plasma concentration was 49.46 micrograms/ml. The oral bioavailability of permethrin was found to be 60.69%. The plasma concentration-time data for permethrin metabolites as well as the tissue concentration-time data for permethrin and its metabolites after an oral dose of permethrin were found to fit a one-compartment open model. The elimination half-life (t1/2el) of permethrin was greater for the hippocampus, medulla oblongata, frontal cortex, and sciatic nerve (23.10, 22.36, 13.86, and 16.27 hr, respectively) than for plasma (t1/2 beta, 12.37 hr). The maximum amounts of permethrin in cerebellum, hippocampus, caudate putamen, frontal cortex, hypothalamus, and sciatic nerve were about 1.5, 2, 2, 2.7, 4.8, and 7.5 times higher than in plasma, respectively, indicating an accumulation of pyrethroid by nervous tissue itself. Nervous tissue accumulation of permethrin was also reflected by the area under the concentration curve ratios of tissue/plasma (1.16, 3.71, 1.57, 4.27, 3.48, and 8.77, respectively). The metabolites of permethrin, m-phenoxy-benzyl alcohol and m-phenoxybenzoic acid, were detected in plasma and in all selected tissues for 48 hr after dosing, suggesting that a combination of metabolism by the tissues and diffusion into it from the blood may be present.

Evidence that alpha 2-adrenergic pathways play a major role in growth hormone (GH) neuroregulation: alpha 2-adrenergic agonism counteracts the inhibitory effect of muscarinic cholinergic receptor blockade on the GH response to GH-releasing hormone, while alpha 2-adrenergic blockade diminishes the potentiating effect of increased cholinergic tone on such stimulation in normal men

The aim of this study was to investigate the interrelationships between alpha 2-adrenergic and cholinergic pathways in the control of hypothalamic somatostatin (SRIF) secretion in humans. In eight normal volunteers subjects we compared the pattern of GHRH-induced GH release to that elicited by similar challenge given 60 min after a pretreatment with drugs affecting alpha 2-adrenergic and muscarinic cholinergic neurotransmission. In a control study, synthetic GHRH [GRF-(1-29); 1 microgram/kg, iv] was administered 60 min after giving placebo. In other experiments, the administration of atropine (1 mg, im), or clonidine (0.300 mg, orally), or atropine plus clonidine, or pyridostigmine (120 mg, orally), or yohimbine (30 mg, orally), or pyridostigmine plus yohimbine, at 0 min was followed by GHRH administration 60 min later. The administration of both clonidine and pyridostigmine significantly (P less than 0.01) enhanced the GH responses to GHRH compared to those elicited by this challenge when given after placebo. Conversely, atropine pretreatment significantly (P less than 0.01) blocked the GH response to GHRH challenge, whereas yohimbine did not significantly affect it. When atropine and clonidine were given together, the inhibitory effect of the former was overcame and mean GHRH-elicited GH peak response was significantly (P less than 0.05) higher than that in the control study. In contrast, pretreatment with yohimbine significantly (P less than 0.05) blunted the pyridostigmine-induced enhancement of GHRH-elicited GH release. These data confirm our previous postulate suggesting that the stimulatory effect of clonidine on GH release is mainly exerted by inhibiting the hypothalamic SRIF release. Moreover, the effect of cholinergic neurons on SRIF release seems to be, at least in part, dependent on alpha 2-adrenergic pathways. Based on these data, it can be proposed that the alpha 2-adrenergic system plays a major role in the control of hypothalamic SRIF release, and hence in GH neuroregulation, whereas the muscarinic cholinergic system would participate in such regulation by modulating the functional activity of the former.

Sonographic diagnosis of traumatic separation of the proximal femoral epiphysis in the neonate

Traumatic separation of the proximal femoral epiphysis is an uncommon birth injury that is difficult to diagnose early. A case is presented in which ultrasonography (US) was used to demonstrate the physeal injury. Early recognition of this injury with US may help prevent development of a permanent coxa vara deformity.

The role of sexual steroids in the modulation of growth hormone (GH) secretion in humans

Sex steroids contribute to modulate GH secretion in man. However, both the exact locus and mechanism by which their actions are exerted still remain not clearly understood. We undertook a number of studies designed to ascertain: (1) whether or not sudden or chronic changes in circulating gonadal steroids may affect GH secretion in normal adults; and (2) the reason(s) for gender-related dimorphic pattern of GH release. The pituitary reserve of GH, as evaluated by means of a GHRH challenge, was similar in women with anorexia nervosa and in normally menstruating women. Estrogenic receptor blockade with tamoxifen (TMX) did not significantly change GHRH-induced GH response in these normal women. Therefore, acute or chronic hypoestrogenism apparently had no important effects at level of somatotrophs. In another group of normal women we tested the possibility that changes in circulating estrogens might induce changes in the hypothalamic-somatotroph rhythm (HSR). GHRH challenges were performed throughout a menstrual cycle, and again after having achieved functional ovarian blockade with a GnRH agonist treatment. Short-term ovarian blockade did not significantly affect the parameters of GH response to GHRH, although it was accompanied by an increase in the number of women in a refractory HSR phase at testing. This suggested a low potentiating effect on the basic pattern of somatostatin (SS) release occurring as a consequence of the decrease in circulating estrogens. In normal men, neither the GH response to GHRH nor the HSR were affected by functional testicular blockade (after GnRH agonist treatment). However, the administration of testosterone enanthate (250 mg) to another group of men increased both the GHRH-induced GH release and the number of subjects in a spontaneous secretory HSR phase at testing; these were reversed by estrogenic receptor blockade with TMS. In another group of normal men, the fraction of GH secreted in pulses (FGHP) during a nocturnal sampling period was significantly decreased by testicular blockade. Other parameters of GH secretion,such as the number of GH pulses and their mean amplitude (A), and the mean plasma GH concentration (MCGH), showed a slight, although not significant, decrease following the lack of androgens. The administration of testosterone enanthate (500 mg) reversed these parameters to values similar to those in the basal study. Interestingly, when tamoxifen was given after testosterone enanthate, A, MCGH and FGHP increased to values significantly higher than in any other experimental condition in that study.(ABSTRACT TRUNCATED AT 400 WORDS)

Effect of ciprofloxacin on antipyrine pharmacokinetics and metabolism in rats

The effect of ciprofloxacin pretreatment on the pharmacokinetics and metabolism of antipyrine in male rats was studied. The animals received oral antipyrine (20 mg/kg of body weight) with and without ciprofloxacin pretreatment (40 mg/kg orally once a day for 8 days). The total plasma clearance of antipyrine was decreased from 0.130 +/- 0.007 to 0.090 +/- 0.005 liter/h (mean +/- standard error of the mean) (P less than 0.01) by ciprofloxacin, while the half-life at beta (elimination) phase and the area under the concentration-time curve for antipyrine were increased from 1.90 +/- 0.22 to 2.83 +/- 0.29 h (P less than 0.05) and from 43.25 +/- 3.35 to 52.41 +/- 2.31 mg.h/liter (P less than 0.05), respectively. The urinary excretions of norantipyrine, 4-hydroxyantipyrine, and 3-hydroxymethylantipyrine decreased by 73, 43, and 54%, respectively (P less than 0.001), in the 96 h after ciprofloxacin treatment. In addition, the rate constants for formation of each of these metabolites were significantly decreased, by an average of approximately 75%. These results suggest that ciprofloxacin is capable of inhibiting oxidative metabolism. This finding could be of clinical significance for drugs that are highly dependent of metabolic pathways, such as those inhibited in this study.

Changes in neuromuscular transmission of guinea pig vas deferens produced by decamethrin treatment

Responses of the isolated vas deferens of guinea pig to clonidine (inhibition of contractions to field stimulation at 2.5 Hz), tyramine (inhibition of contractions to field stimulation at 10 Hz), prostaglandin E2 (inhibition of contractions to field stimulation at 10 Hz), and noradrenaline (contraction of longitudinal muscle) were determined after administration of decamethrin (18 mg kg-1, ip) once a day for 3 consecutive days. Treatment with decamethrin produced a subsensitivity of the prejunctional alpha 2-adrenoceptor system as evidenced by the fact that the alpha 2-agonist clonidine was less effective in decreasing nerve-stimulated induced contractions of the vas deferens. In addition, the presynaptic action of tyramine on postganglionic motor transmission was impaired. However, no detectable changes in the inhibition by prostaglandin E2 of twitch responses were produced by decamethrin. Decamethrin treatment had a significant effect on noradrenaline responsiveness, causing an increase in the maximum contractile response, indicative of an enhanced postreceptor mechanism. The present results suggest that decamethrin treatment reduces peripheral presynaptic adrenoceptor sensitivity. This reduction will lead subsequently to increased noradrenaline release and postsynaptic adrenoceptor upregulation.

Pharmacokinetics of tetracycline in chickens after intravenous administration

Plasma levels of tetracycline in chickens were determined after intravenous (iv) administration of a 65-mg/kg dose. The disposition kinetics of tetracycline in chickens were fitted to a two-compartment open model. Pharmacokinetic parameters were found to be: A (microgram/ml) = 2000 +/- 450, alpha (hr-1) = 4.3 +/- .5, B (microgram/ml) = 82 +/- 6, beta (hr-1) = .252 +/- .009, K12 (hr-1) = 1.515, K21 (hr-1) = .049, and K10 (hr-1) = 2.652. Biliary excretion of tetracycline was also studied in chickens fitted with cannulae inserted into both bile ducts. The maximum values for tetracycline biliary excretion rate (407 and 606 micrograms/hr) were reached at about 1 hr after iv administration of 10- and 15-mg/kg doses. First-order rate constants for the biliary excretion, Kbi (hr-1), were .834 and .665, respectively. The cumulative biliary excretion study showed that about 7% of both administered doses was recovered from the bile within the first 6 hr. In contrast, there was a low recovery of antibiotic in the bile after oral administration of 100 and 200 mg/kg doses.