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Biomedical subjects

Z Z Wang

Publications and source records attributed to Z Z Wang.

17 recordsLinked to original sources
PubMed1992

Serotonin-like immunoreactivity in Merkel cells and their afferent neurons in touch domes from the hairy skin of rats.

Immunoreactivity to serotonin was observed in Merkel cells as well as the afferent type I nerves terminating upon them in touch domes excised from the belly skin of rats. Type I nerves were strongly immunoreactive and could be traced through the dermis of the domal papilla. Merkel cell immunoreactivity was sometimes seen in the entire cell, but was often localized in the Merkel cell cytoplasm adjacent to nerve terminals and may have been in the terminals themselves. Domes were fixed by immersion in 4% paraformaldehyde-lysine-sodium-m-periodate (PLP) fixative at 4 degrees C for 2.5-3 hours and cryoprotected in 30% sucrose overnight. Sections were processed with the avidin-biotin complex peroxidase (ABC), peroxidase-antiperoxidase (PAP), and indirect immunofluorescence techniques with rabbit antiserum generated against serotonin.

Afferent Pathways↗
PubMed1992

Atrial natriuretic peptide increases cyclic guanosine monophosphate immunoreactivity in the carotid body.

The mammalian carotid body is a peripheral arterial chemoreceptor organ involved in the regulation of respiration, and in the modulation of blood pressure through reflex control of peripheral vascular resistance and cardiac output. In addition to its responsiveness to blood gases, the organ is also sensitive to hyperosmotic solutions, and we have recently shown that a systemic hormonal regulator of natriuresis and diuresis, atrial natriuretic peptide, is a potent inhibitor of chemoreceptor activity evoked by hypoxia in the cat carotid body. The present study demonstrates atrial natriuretic peptide immunoreactivity in type I cells of the carotid body, and shows further that a biologically active atrial natriuretic peptide fragment, atriopeptin III, increases cyclic guanosine monophosphate immunoreactivity in type I cells in a dose-dependent manner. Moreover, double-labeling techniques demonstrate co-existence of atrial natriuretic peptide immunoreactivity with the atriopeptin III-enhanced cyclic guanosine monophosphate reaction product. These findings indicate the probable existence of atrial natriuretic peptide receptors coupled to membrane-bound guanylate cyclase on the parenchymal type I cells. Our findings support the view that cyclic guanosine monophosphate functions as a second messenger in this organ, and may serve as a functional activity marker in identifying type I cells which respond to atrial natriuretic peptide.

Animals↗
PubMed1992

The co-existence of biogenic amines and neuropeptides in the type I cells of the cat carotid body.

The mammalian carotid body consists of preneural type I (glomus) cells synaptically coupled to afferent axon terminals and enveloped by type II (sustentacular) cells. Recent studies indicate the presence of multiple putative neurotransmitters in this arterial chemoreceptor organ. A double-labeling immunocytochemical technique was utilized which allows simultaneous visualization of two neurochemicals in a single cell. The issue of transmitter co-occurrence in type I cells of the cat carotid body was addressed using specific antibodies for seven neurochemical agents: tyrosine hydroxylase, dopamine-beta-hydroxylase, choline acetyltransferase, serotonin, substance P, met-enkephalin and chromogranin. A high degree (greater than 70%) of co-localization was observed for most pairs of markers, indicating the co-existence of multiple neuroactive agents in type I cells of the cat carotid body. The intensity of staining varied greatly among cells but formed a pattern. Thus, for tyrosine hydroxylase and dopamine-beta-hydroxylase, the majority of double-labeled type I cells exhibited equivalently low or high levels of both, while for the neuropeptides unequal levels of the two markers predominated. Neuropeptides also co-existed in type I cells with catecholamine-synthesizing enzymes and with serotonin. The functional significance of such patterns of multiple co-existence involving biogenic amines and neuropeptides is discussed. Our results indicate a high degree of co-occurrence of reaction product for amine-synthesizing enzymes (tyrosine hydroxylase, dopamine-beta-hydroxylase and choline acetyltransferase), the indoleamine serotonin, and the neuropeptides substance P and met-enkephalin.

Animals↗
PubMed1991

Immunocytochemical localization of cAMP and cGMP in cells of the rat carotid body following natural and pharmacological stimulation.

Although the chemoreceptive function of the carotid body has been known for many decades, the cellular mechanisms of sensory transduction in this organ remain obscure. Common elements in the transductive processes of many cells are the cyclic nucleotide second messengers, cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP). Studies from our laboratory have revealed stimulus-induced changes in cyclic nucleotide levels in the carotid body as measured by RIA, but such changes in second messenger levels have not been localized to specific cellular elements in the organ. The present immunocytochemical study utilized the avidin-biotin-peroxidase method to investigate the distribution of cAMP and cGMP in the rat carotid body and to assess changes in the intensity of immunostaining following in vitro stimulation by hypoxia, forskolin, sodium nitroprusside, high potassium, and atrial natriuretic peptide. Both cAMP and cGMP immunoreactivity were localized to type I cells of organs maintained in vivo and fixed by perfusion. Organs exposed to 100% O2-equilibrated media in vitro produced low but visible levels of cAMP immunoreactivity in a majority of type I cells; hypoxia (5% O2-equilibrated media) for 10 min moderately increased the level of immunoreactivity; forskolin (10(-5) M), or forskolin combined with hypoxia, dramatically increased cAMP levels in virtually all cells. Moderate levels of cGMP immunoreactivity in control carotid bodies in vitro were strikingly reduced by hypoxia; a significant increase in cGMP levels occurred following incubation in high potassium (100 mM), and under these conditions, the decrease in cGMP immunoreactivity with hypoxia was much more pronounced.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1991

Co-existence of tyrosine hydroxylase and dopamine beta-hydroxylase immunoreactivity in glomus cells of the cat carotid body.

Catecholamines are thought to play an important role in sensory transduction in the arterial chemoreceptors of the mammalian carotid body, and classical cytochemical techniques have demonstrated their presence in the type I (glomus) cells of this organ. However, it remains controversial whether dopamine (DA) and norepinephrine (NE) occur in the same or in different subtypes of glomus cells. In the present study, we have addressed this issue using immunocytochemistry to compare the localization of tyrosine hydroxylase (TH) and dopamine beta-hydroxylase (D beta H) in the cat carotid body. Both pre- and post-embedding double-labelling immunohistochemical techniques were employed. TH and D beta H were found to co-exist in over 90% of the glomus cells, and they were co-localized at equivalent levels in almost 80% of the cells; less than 5% contained only TH. The results suggest that DA and NE are synthesized and stored in a common cell population in the cat carotid body.

Animals↗
PubMed1991

Localization and in vitro actions of atrial natriuretic peptide in the cat carotid body.

Previous studies of atrial natriuretic peptide (ANP) have indicated that its release from the heart and from discrete areas of the central nervous system evokes coordinated physiological and behavioral adjustments that mitigate the adverse hypertensive effects of volume overload and/or acute increases in sodium intake. Because the reflex activity initiated by arterial chemoreceptors of the carotid body directly contributes to the integrated regulation of systemic blood pressure, we have investigated the possibility that ANP has a significant role in the chemosensory process as well. Our immunocytochemical studies show that ANP-like immunoreactivity is present in the preneural chemosensitive type I cells in the cat carotid body. Furthermore we found that the biologically active ANP fragment atriopeptin III is a potent inhibitor of carotid sinus nerve activity evoked by hypoxia. Our findings suggest that circulating and/or endogenous ANP may modulate carotid body function as part of a coordinated response to changes in systemic volume and solute balance.

Animals↗
PubMed1991

Observations on experimental infection of periodic Brugia malayi in man.

Three volunteers were inoculated with different numbers of infective larvae of periodic Brugia malayi from an artificially infected Meriones unguiculatus. At different times after inoculation, the volunteers developed clinical manifestations such as chills, fever, cough, asthma, skin itching, edema, adenolymphangitis and eosinophilia. Microfilaremia was first detected at 41 and 46 weeks after inoculation in two subjects. At 11 weeks, the percentage of E-rosette forming lymphocytes in these subjects was below the normal level. Specific antibody was first detected in three volunteers at 2, 3 and 5 weeks after inoculation, respectively, and increased to various extent at 12-16 weeks, but decreased in varying degrees at 44-56 weeks. The results also showed that antibody titres fluctuated at different periods of infection.

Adolescent↗
PubMed1989

Immunocytochemical localization of choline acetyltransferase in the carotid body of the cat and rabbit.

The carotid body consists of afferent axon terminals in synaptic association with preneural type I cells and enveloping type II cells. The presence of acetylcholine (ACh) in this organ and its pharmacological actions are well established; however, its precise localization remains uncertain. In the present study, choline acetyltransferase was immunocytochemically localized to type I cells of the cat and rabbit. These data, combined with previous demonstrations of cholinergic receptor action, suggest that ACh may be involved in neurotransmitter coupling in the carotid body.

Animals↗
PubMed1989

[Endonasal removal of pituitary growth hormone-adenoma: report of 56 cases].

Fifty-six cases of pituitary GH-adenoma removed by endonasal method are reported. In 50 cases, plasma hGH decreased postoperatively. According to biological evaluation, 18 patients were cured, 21 were improved and 17 presented no change. Postoperative high hGH (greater than or equal to 5 ng/ml) indicated that there were some residual functioning tumor cells in the Sella. Such cases must be followed up regularly in order to assess when and what treatment should be given. Postoperative radiation usually raises the curability of acromegaly. Endonasal method is simple, effective and less injurious to the neighboring structure of the nose.

Adenoma, Acidophil↗
PubMed1985

Changes in contralateral brain-stem auditory evoked responses to cerebellopontine angle compression in rats.

Eleven rats were subjected to graded compression of the brain stem at the cerebellopontine angle (CPA) following craniectomy and cerebellectomy. Clicks were delivered to the ear contralateral to the compression site, and brain-stem auditory evoked responses (BAER's) were collected before and during compression. With increasing compression, there was an increase in the latency and a decrease in the amplitude of the peaks of the BAER. The later peaks of the BAER (V and VI) demonstrated changes with minimal compression that progressed as compression increased, while changes in the amplitude and latency of the earlier peaks (II, III, and IV) occurred at the higher grades of compression. Following decompression of the brain stem, there was a decrease in the latencies of most of the BAER peaks. Peak amplitude remained depressed following brain-stem decompression. These experimental findings corroborate clinical reports of abnormal BAER's elicited from stimulation of the ear contralateral to a CPA tumor. The relative sensitivity of the later peaks of the BAER to even minimal brain-stem compression explains the prolonged III to V interpeak latency reported in the literature in patients with brain-stem compression from a CPA lesion. The possible mechanisms for the BAER changes that were observed contralateral to compression are discussed.

Animals↗
PubMed1985

Fluorescence properties of insulin analogs with tryptophan substitutions.

The fluorescence properties of four insulin analogs with tryptophane substitutions, [L-Trp]A1 insulin, [D-Trp]A1 insulin, [L-Trp]B1 insulin and desPheB1 [L-Trp]B2 insulin, have been studied. The effect of pH on the fluorescence behaviours of the three L-Trp insulin analogs are similar to only one fluorescence intensity peak at pH 9. [D-Trp]A1 insulin shows two fluorescence intensity peaks, a main peak at pH 9.8 and a small peak at pH 5.5. The fluorescence quenching on the acid side of the pH approximately 9 peak is caused by protonation of the A1 alpha-amino group. The difference in A1 alpha-amino group pK values of these derivatives, the presence of a second pH-fluorescence peak for the D-Trp derivative and other differences reflect differences in molecular conformation of the two A1-insulin analogs which could form the basis of the pronounced differences in their biological activities.

Chemical Phenomena↗