Prejunctional and postjunctional effects of neuropeptide Y at the noradrenergic neuroeffector junction of the perfused mesenteric arterial bed of the rat

The effect of neuropeptide Y (NPY) on periarterial nerve stimulation-induced release of norepinephrine (NE) and increase in perfusion pressure in the perfused mesenteric arterial bed of the rat was examined. Perfusate effluents were continuously collected and assayed for endogenous NE by high-pressure liquid chromatography (HPLC) coupled to electrochemical detection. Perfusion pressure was continuously monitored by means of a pressure transducer. Periarterial nerve stimulation (8 or 16 Hz, 60 V, 2-ms duration for 30 s) resulted in a readily detectable increase in NE release and perfusion pressure that was attenuated by the prior administration of tetrodotoxin (TTX) (10(-5) M) or guanethidine (5 X 10(-5) M). NPY exerted both prejunctional and postjunctional effects on noradrenergic neurotransmission in this preparation. The peptide produced a concentration-dependent reduction in the release of NE over a concentration range of 10(-10) - 10(-7) M. A similar inhibition effect occurred at 8, 10, and 16 Hz. In contrast, low concentrations (10(-10) and 10(-9) M) decreased the effect of nerve stimulation on perfusion pressure, whereas higher concentrations (10(-7) M) produced a marked potentiation. The alpha 2-adrenoceptor antagonist, yohimbine, did not alter the inhibitory effect of NPY on evoked NE release or the effect on perfusion pressure. Prazosin similarly did not alter the inhibitory effect of NPY on NE release but prevented the increase in perfusion pressure. We conclude that NPY modulates noradrenergic neurotransmission in the mesenteric arterial bed by decreasing the evoked release of NE and producing a concentration-dependent biphasic response on vascular smooth muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Magic and myth of migration: a case study of a special economic zone in China

The town of Shenzhen, China, experienced rapid economic and demographic growth following the government's creation of four Special Economic Zones in 1980. The role of migration in the Shenzhen phenomenon is examined as a practicum for policymakers and demographic specialists. Specifically, the paper is concerned with "the sources and mechanisms of migration, and characteristics of migrants to Shenzhen in order to clarify the relationship between rapid economic growth and its demographic consequences in China. It also briefly assesses the problems associated with migration to Shenzhen and how they may affect the city's future."

Protective effects of captopril and enalapril on myocardial ischemia and reperfusion damage of rat

The protective effect of angiotensin-converting enzyme inhibitors (ACEI) on myocardial ischemia and reperfusion damage was estimated in rat hearts, both in vivo and in vitro. Enalapril 2.5 mg/kg ip pretreatment at 24 and 5 h before coronary occlusion, significantly blunted the rise of CPK (445 +/- 151 vs 649 +/- 244 mu/ml, P less than 0.05) and improved electrocardiogram (ECG) 8 h after coronary occlusion. In global ischemia and reperfusion ex vivo, enalapril improved contractility (0.9 +/- 0.2 vs 0.3 +/- 0.3 g, P less than 0.05) and coronary flow (15.6 +/- 3.3 vs 11.9 +/- 3.1 ml/min/g, P less than 0.05), shortened significantly the duration of reperfusion arrhythmia (3.1 +/- 2.7 vs 9.7 +/- 8.1 min, P less than 0.05). In Langendorffs heart, captopril remarkably preserved force of contraction (2.1 +/- 0.4 vs 1.4 +/- 0.4 g, P less than 0.01) and coronary flow (2.7 +/- 0.5 vs 3.6 +/- 0.9 ml/min/g, P less than 0.05) in segmental infarction deteriorated by angiotensin I. Captopril 10(-5) M infusion reduced the release of CPK (435 +/- 112 vs 640 +/- 123 mu/min coronary flow, P less than 0.05). This action was almost completely abolished by pretreating and infusing with indomethacin. As a positive control, prostacyclin 5 X 10(-7) M infusion further reduced the release of CPK to 330 +/- 77 mu/min. It is concluded that angiotensin-converting enzyme inhibitor can protect both myocardial ischemia and reperfusion damage in rat hearts. The mechanism of protection was ascribed to reduced production of angiotensin II by ACE inhibition and increased prostacyclin release in the myocardium.

[Promoting effect of the Chinese medicinal herb, wikstroemia chamaedaphne and tung oil extracts on carcinoma of the uterine cervix induced by HSV-2 or methylcholanthrene (MCA) in mice]

The promoting effect of the Chinese medicinal herb, Wikstroemia chamaedaphne and Tung oil extracts (WC and HHPA) on carcinoma of uterine cervix induced by HSV-2 or MCA in mice was studied. The results showed that WC and HHPA extracts were not carcinogenic themselves. After carcinogen HSV-2 and MCA treatment, WC and HHPA were added separately. The inducing rates by HSV-2 increased from 7.4% to 21.1% and 26.3%, those by MCA increased from 56.5% to 82.8% and 84.4%. There was a significant difference between the combined groups and groups with HSV-2 or MCA only. The experimental results suggest that these two kinds of extracts play a promoting effect on carcinogenesis. The relation between the carcinogenesis of uterine cervix or nasopharynx and WC or HHPA extracts is discussed.

[The induction of sister chromatid exchange by diethylstilbestrol and mitomycin C in lymphocytes of mothers and their newborn infants]

Lymphocytes of mothers and their newborn infants were treated with varying concentrations of diethylstilbestrol (10(-6) M, 10(-5) M and 10(-4) M) and mitomycin C (0.003, 0.009 and 0.03 microgram/ml), and the incidence of sister chromatid exchanges (SCE) was determined. The results showed that the spontaneous SCE rate in the newborns is less than that of their mothers. A dose-related increase in SCEs was observed in cells exposed to the alkylating chemical mitomycin C, while increases in SCEs were not noted in cultures exposed to diethylstilbestrol. No different susceptibilities of lymphocytes from mothers and newborns to the chemical induction were observed.

DNA hybridization for human papillomavirus (HPV) in cervical lesions. Relationship of the presence of various viral subtypes to expression of HPV structural proteins, involucrin, and carcinoembryonic antigen

We studied cervical tissue from 20 patients with a variety of condylomatous, preneoplastic, and neoplastic lesions to detect various subtypes of human papillomavirus (HPV) at the molecular level by DNA hybridization. In addition, mirror image biopsy specimens were studied by an immunoperoxidase technique for the presence of HPV structural antigens, carcinoembryonic antigen (CEA), and involucrin, as markers of disturbed maturation and/or neoplasia. Of the 20 patients studied, we were able to demonstrate the presence of either HPV 16 or 18, or both, in three of seven squamous carcinomas tested, and three of five dysplasias. Interestingly, two cases of squamous carcinoma and one moderate dysplasia demonstrated HPV types 6 and 11 concurrently with HPV 16 and/or 18. Four of six condylomas showed HPV subtypes 6/11, and only one condyloma showed weak hybridization with HPV 18. Human papillomavirus structural antigen was seen in three of eight condylomas, and three of five dysplasias, but not in any carcinoma. All condylomas showed intense staining for involucrin in full-thickness of the epithelium, but the high-grade dysplasias and carcinomas showed only focal or absence of staining for involucrin. Carcinoembryonic antigen was expressed in 50% of the carcinomas with a pattern similar to that seen with involucrin, but did not correlate with any particular subtype of HPV. The molecular hybridization method seems to be superior for the detection of HPV lesions, and possibly for the prediction of their biologic behavior.