The N-terminal portion of parathyroid hormone-related protein mediates the inhibition of apical Na+/H+ exchange in opossum kidney cells

Parathyroid hormone (PTH) and PTH-related protein (PTHrP) can activate a common receptor in several different cell types. Both PTH and N-terminal PTHrP peptides have been shown to acutely inhibit the apical Na+/H+ exchanger in the renal proximal tubule. In this study, the ability of various PTHrP fragments to inhibit apical Na+/H+ exchange was investigated. In addition, the signal transduction events associated with PTHrP inhibition of apical Na+/H+ exchange in polarized OK-P cells were characterized. Both PTHrP-(1-34)NH2 and recombinant full-length PTHrP-(1-141) inhibited apical Na+/H+ exchange activity by approximately 50%. These changes occurred in close temporal association with significant (threefold) increases in cellular cAMP accumulation. PTHrP-(1-34)NH2 had no effect on intracellular Ca2+, inositol phosphate production, or protein kinase C activity. PTHrP peptides, including PTHrP-(38-64)NH2, PTHrP-(67-86)NH2, PTHrP-(102-107)NH2, and PTHrP-(107-139)NH2, which lack the PTH-like N terminus, had no effect on the antiporter activity or cAMP accumulation. The results demonstrate that the N-terminal portion of the PTHrP molecule is responsible for inhibition of the apical Na+/H+ antiporter in OK-P cells.

Chronic exogenous hyperinsulinemia in pregnancy: a rat model of pregnancy-induced hypertension

Insulin resistance and hyperinsulinemia are associated with essential hypertension. There is also evidence of hyperinsulinemia in women who developed hypertension in pregnancy (P). The present study examines whether chronic hyperinsulinemia in pregnant rats plays a role in the development of hypertension in pregnancy. A sustained-release insulin pellet was implanted subcutaneously in 15 Wistar rats (P-INS) 1 wk before and on day 7 of pregnancy; 14 control rats were sham-implanted (P-SHAM). Tail-cuff systolic BP (SBP), serum triglycerides, glucose, insulin, renal function, and urinary excretion of Na+ and of metabolites of nitric oxide were determined throughout pregnancy. Data were analyzed by ANOVA with basal body weight as covariate analysis of covariance. Results are expressed as the mean +/- SD. Body weight; water and food intake; urine volume; creatinine clearance; and level of proteinuria at the end of pregnancy were similar in both groups. The number of fetuses was 9 +/- 2.3 in P-INS versus 11 +/- 2.4 in pregnant control rats (P < 0.05). Before mating, SBP was similar, but at the end of pregnancy SBP was 110 +/- 18 mmHg in P-INS versus 85 +/- 12 mmHg in pregnant rats (P < 0.05). Serum triglycerides and Na+ were also higher in P-INS rats. The fractional excretion of Na+ was 3.1 +/- 1.0 versus 4.4 +/- 1.5, respectively (P < 0.01). The percent increase in nitric oxide metabolite excretion was 233 +/- 14 versus 370 +/- 17%, respectively (P < 0.01). Chronic hyperinsulinemia, without sugar supplementation, and hypertriglyceridemia may cause a decrease in the synthesis of nitric oxide in P-INS rats. The development of hypertension in these rats may be associated with an impaired vasodilatation, together with an increased renal sodium reabsorption.

Foundations for a healthy future

Health promotion activities with children and young people are important as they take messages about health seriously and can be influential in spreading messages about healthy living to their friends and families. Child health professionals have an important role to play in passing on messages of positive health to children and young people. Peer education is a useful way of passing on messages about health to young people. This article shares examples of three health promotion projects with children in a community trust, looking at asthma, sex education and testicular examination.

Illinois Dental Anesthesia and Sedation Survey for 1996

Dentists in the state of Illinois who possess a permit to administer sedation or general anesthesia were surveyed. A 71% response rate was achieved. Of the respondents, 86% held permits for deep sedation/general anesthesia and 14% held permits for parenteral conscious sedation. By practice specialty, 84% were oral and maxillofacial surgeons, 11% were general dentists, 5% were periodontists, and fewer than 1% were dental anesthesiologists. Advanced Cardiac Life Support training was possessed by 85% of the respondents. The most common anesthesia team configuration (82%) was a single operator-anesthetist and two additional assistants. Only 4% reported use of a nurse anesthetist, and 2% used an additional MD or DDS anesthesiologist. The vast majority (97%) of the practitioners do not intubate in the office on a routine basis. Supplemental oxygen was used by 81% of the respondents whenever intravenous agents were used. A total of 151,335 anesthetics were administered during the year. One mortality occurred in a patient with an undisclosed pre-existing cardiac condition. Four other events were reported that required medical intervention or hospital evaluation; however, no permanent injuries were reported. Other practice characteristics were described.

Multiple pregnancy-associated glycoproteins are secreted by day 100 ovine placental tissue

Pregnancy-associated glycoprotein (PAG)-1 (PAG1) and pregnancy-specific protein B are either identical or closely related antigens released by trophoblast binucleate cells of placentas of cattle. Sheep and other ruminants produce similar products. There is evidence, however, that these antigens, which are related structurally to the pepsinogens and other aspartic proteinases, are not single gene products but members of an extensive family. Here, the sequential use of ammonium sulfate precipitation and Sepharose blue, anion-exchange, and cation-exchange chromatographies, as well as isoelectric elution from a Mono P column, has allowed several PAG1-related molecules to be purified from the medium after culture of explants from Day 100 sheep placentas. Each of these PAGs cross-reacted to a varying extent with a panel of three different anti-PAG1 antisera. Four of them, all of which were major secretory products of the placenta, were subjected to amino-terminal microsequencing. Although each was related to ovine (ov) PAG1, none was identical. Reverse transcription-polymerase chain reaction was then used to amplify PAG1-related cDNA from Day 100 placental RNA. Seven novel full-length cDNA, all distinct from ovPAG1, were identified from 25 cDNA selected for sequencing. Only two of these (ovPAG3 and ovPAG7) encoded polypeptides identical in sequence at their inferred amino termini to one of the PAGs (ovPAG65) purified from explant cultures. Even so, they were only 84% identical in overall sequence. The remaining five cDNA were unique. In situ hybridization analysis revealed that expression of ovPAG3 and ovPAG7, like that of ovPAG1, is confined to trophoblast binucleate cells. The data confirm that at Day 100 of pregnancy the ovine placenta produces many different PAGs, which differ considerably in sequence and immunological cross-reactivity.

The diversity and evolutionary relationships of the pregnancy-associated glycoproteins, an aspartic proteinase subfamily consisting of many trophoblast-expressed genes

The pregnancy-associated glycoproteins (PAGs) are structurally related to the pepsins, thought to be restricted to the hooved (ungulate) mammals and characterized by being expressed specifically in the outer epithelial cell layer (chorion/trophectoderm) of the placenta. At least some PAGs are catalytically inactive as proteinases, although each appears to possess a cleft capable of binding peptides. By cloning expressed genes from ovine and bovine placental cDNA libraries, by Southern genomic blotting, by screening genomic libraries, and by using PCR to amplify portions of PAG genes from genomic DNA, we estimate that cattle, sheep, and most probably all ruminant Artiodactyla possess many, possibly 100 or more, PAG genes, many of which are placentally expressed. The PAGs are highly diverse in sequence, with regions of hypervariability confined largely to surface-exposed loops. Nonsynonymous (replacement) mutations in the regions of the genes coding for these hypervariable loop segments have accumulated at a higher rate than synonymous (silent) mutations. Construction of distance phylograms, based on comparisons of PAG and related aspartic proteinase amino acid sequences, suggests that much diversification of the PAG genes occurred after the divergence of the Artiodactyla and Perissodactyla, but that at least one gene is represented outside the hooved species. The results also suggest that positive selection of duplicated genes has acted to provide considerable functional diversity among the PAGs, whose presence at the interface between the placenta and endometrium and in the maternal circulation indicates involvement in fetal-maternal interactions.

FNR is a direct oxygen sensor having a biphasic response curve

FNR is a transcription regulator that controls the expression of target genes in response to anoxia. Anaerobiosis is accompanied by the acquisition of two [4Fe-4S]2+ clusters per FNR dimer and the ability to bind DNA site-specifically. Oxidation of the [4Fe-4S]2+ form of FNR by O2 produced a non-DNA-binding, transcriptionally inactive form which also contains an iron-sulfur cluster, recently identified by Mossbauer spectroscopy as a [2Fe-2S] cluster (Khoroshilova et al., 1997, PNAS. 94, 6078). Complete conversion needed at least 2.5-3.0 molecules of O2 per [4Fe-4S]2+ cluster. Using sub-stoicheiometric amounts of air-saturated buffer, stable equilibria were established in which the [4Fe-4S]2+ and [2Fe-2S]2+ forms co-exist and no EPR detectable free ferric ions were released. In contrast, a 20-fold molar excess K3Fe(CN)6 was required to oxidise the [4Fe-4S]2+ cluster and in this case, ferric ions were released. FNR is therefore a sensitive O2 sensor.

A dose-ranging pharmacokinetic study of nicotine tartrate following single-dose delayed-release oral and intravenous administration

BACKGROUND

Ulcerative colitis is predominantly a disease of non-smokers, and transdermal nicotine is therapeutic but often results in side-effects. Administration of nicotine tartrate as a liquid enema decreases systemic nicotine absorption and may be effective for treatment of active distal ulcerative colitis. Ileocolonic delivery of nicotine tartrate via a delayed release oral capsule would be the preferred route to deliver nicotine to the colon.

AIM

To determine the bioavailability and pharmacokinetic parameters of delayed-release oral nicotine tartrate capsules (Eudragit S100 coated) at doses of 3 mg and 6 mg nicotine.

METHODS

Twenty healthy human subjects received delayed-release oral nicotine tartrate at one of two doses (each group n = 10): 3 mg and 6 mg nicotine. All subjects also received intravenous nicotine tartrate (at a dose of 15 micrograms nicotine base/kg) during a separate study period. Serum nicotine concentrations were determined by gas chromatography-mass spectrometry. In addition, concentrations of serum cotinine (major nicotine metabolite) were determined by high-performance liquid chromatography in all samples for two subjects (both given 6 mg nicotine). Adverse reactions were determined by questionnaire.

RESULTS

The mean bioavailabilities of nicotine after ileocolonic nicotine tartrate administration via delayed-release oral capsules at doses 3 mg and 6 mg nicotine were 41% and 42%, respectively. The ratios (after adjusting for nicotine dose) of cotinine area under the curve (AUC) for delayed-release oral nicotine to cotinine AUC for intravenous nicotine were 1.5 and 1.6 for the two subjects undergoing cotinine pharmacokinetics, demonstrating significant first-pass metabolism. Serum nicotine concentrations did not predict adverse reactions.

CONCLUSIONS

Nicotine tartrate delivered to the ileocolon as a delayed-release oral capsule at doses of 3 mg and 6 mg nicotine considerably reduced systemic nicotine bioavailability. This reduction in bioavailability appears to be a result of first-pass hepatic metabolism rather than poor mucosal absorption of nicotine. The therapeutic potential of an ileocolonic delivery formulation of nicotine tartrate, which can potentially limit toxicity by local delivery of high doses of nicotine, should be investigated in patients with ulcerative colitis.

Primary and metastatic rhabdomyosarcoma in the breast: neoplasms of adolescent females, a report from the Intergroup Rhabdomyosarcoma Study

The occurrence of rhabdomyosarcoma (RMS) primary in or metastatic to breast has been regarded as an uncommon event, associated with an unfavorable outcome. Records of 26 patients with diagnoses of breast RMS, either primary or secondary, entered in the Intergroup Rhabdomyosarcoma Study (IRS) (1972-1992) were reviewed and compared with data regarding 47 similar patients in published reports. Of the 26 IRS cases, the histologic subtype was alveolar in 24, embryonal in 1, and not determined in 1. All were female with ages ranging from 11.5 to 20.2 years (median, 15.2 years; mode, 14-16 years). This compact age distribution of both primary (n = 7) and metastatic (n = 19) breast RMS was seen in previously reported series. Among the 19 cases of RMS with initial dissemination to breast, primary tumor sites, were extremity (n = 8), nasopharynx/paranasal sinuses (n = 7), and trunk (n = 4). IRS treatment was risk-based according to site and extent of disease. Four of 7 patients with primary RMS remain disease free 2.9 to 7 years post diagnosis. Among 19 patients with RMS initially metastatic to breast, including 7 in IRS clinical group IV at original diagnosis, three are disease free at 7.6, 15.7 and 17.0 years.

CONCLUSIONS

primary or metastatic RMS in breast is almost confined to adolescent females having tumors with alveolar histology. Approximately one-half of the patients with primary breast disease and 15% of those with metastatic breast disease as an initial recurrence are long-term survivors.

Nitric oxide and vascular reactivity in pregnant rats with adriamycin nephropathy

1. In previous studies we have shown that, after the administration of adriamycin, hypertension developed in rats who became pregnant (adriamycin-pregnant rats), whereas virgin animals remained normotensive. Subsequently, we showed that this hypertension was prevented by administration of L-arginine, suggesting that deficient synthesis of nitric oxide may be pathogenetic in this model. 2. To further assess the role of nitric oxide in this model, we measured mean arterial blood pressure after administration of L-arginine to adriamycin-pregnant rats or of NG-nitro-L-arginine-methyl ester (L-NAME) to normal pregnant rats. In other experiments, we assessed the response of isolated perfused arterial mesenteric vessels, precontracted with noradrenaline, to acetylcholine, L-arginine or L-NAME. 3. Blood pressure was decreased in normal pregnant rats, whereas it was elevated in adriamycin-pregnant rats. L-NAME treatment increased blood pressure in normal pregnant rats and L-arginine decreased it in adriamycin-pregnant rats. 4. Mesenteric vessels of adriamycin-pregnant rats exhibited an exaggerated vasoconstrictory response to noradrenaline, when compared with the blunted response observed in normal pregnancy. The addition of L-NAME in vitro induced a further contraction, significantly greater in normal pregnant rats. The vasodilatory response to acetylcholine and L-arginine was greater in vessels from adriamycin-pregnant rats. In contrast, responses to either nitroprusside or diazoxide were similar in all groups. 5. The results suggest a state of reduced nitric oxide synthesis in rats with adriamycin nephropathy, leading to vascular maladaption and hypertension in pregnancy.

Psychological factors in recurrent genital herpes

OBJECTIVES

To review recent research into psychological aspects of genital herpes and assess possible implications for clinical practice.

METHODS

Review of all papers in the field on Medline 1985-96.

RESULTS

Much attention has been paid to possible links between stress and recurrent genital herpes. There is no convincing evidence that stress in itself causes recurrences. It may be that recurrences are preceded by a prodromal period of altered mood. Patients with recurrences show considerable stress as a result of the disease, although most individuals eventually adjust psychologically. The impact of social support on adjustment remains unclear. The little evidence available suggests that antiviral treatments can help adjustment and the effects may perhaps outlast the period of active treatment.

CONCLUSIONS

Existing research gives some clues to optimal patient management but there is a need for future research to focus much more clearly on clinical issues, particularly on means of alleviating psychological distress and on the impact of antivirals.

Nicotine tartrate liquid enemas for mildly to moderately active left-sided ulcerative colitis unresponsive to first-line therapy: a pilot study

BACKGROUND

Ulcerative colitis is predominantly a disease of non-smokers, and transdermal nicotine is therapeutic but often results in side-effects. Administration of nicotine as a liquid rectal enema results in less systemic nicotine absorption.

AIM

To determine the safety and clinical response of nicotine tartrate liquid enemas for active left-side ulcerative colitis in a pilot study.

METHODS

Ten non-smoking patients with mildly to moderately active left-sided ulcerative colitis unresponsive to first-line therapy were treated in an open protocol with nightly nicotine tartrate liquid enemas at a dose of 3 mg nicotine base for 1 week then 6 mg for 3 weeks. Clinical assessments were determined at baseline and 4 weeks by endoscopy, physician assessment and a patient diary of daily symptoms. Peak and trough serum nicotine and trough plasma cotinine were determined by gas chromatography/mass spectrometry and high performance liquid chromatography, respectively.

RESULTS

After 4 weeks of treatment, 5/7 patients (71%) showed clinical and sigmoidoscopic improvement (per protocol analysis). The other three patients discontinued therapy within 7 days because of inability to retain the liquid enemas. No patients showed histologic improvement. Six of the patients who completed the 4-week study had peak and trough serum nicotine concentration determined, only 1 of 6 patients had a detectable peak nicotine concentration (value 2.3 ng/mL), and all six patients had undetectable trough nicotine concentrations. The mean trough plasma cotinine concentration was 13 +/- 10 ng/mL. Transient and mild adverse events occurred in 4/10 patients (nausea, lightheadedness, tremor, sleep disturbance). Given the low or undetectable serum nicotine concentrations, these adverse events are not likely to be related to the nicotine enemas.

CONCLUSIONS

Nicotine tartrate liquid enemas administrated at a dose of 3 mg nicotine base/day for 1 week and then 6 mg/day for 3 weeks are safe and appear to result in clinical improvement in some patients with mildly to moderately active, left-sided ulcerative colitis unresponsive to first-line therapy. Placebo-controlled trials are warranted to confirm these preliminary findings.