Biomedical subjects

Y C Lin

Publications and source records attributed to Y C Lin.

At least 199 records · Page 11Linked to original sources

PubMed1994

Detection of keratinocyte growth factor (KGF) transcripts from normal human and archival canine benign prostatic hyperplastic tissues.

This study examined the expression of keratinocyte growth factor (KGF) gene in human and canine prostatic tissues. KGF transcript was detected in normal human prostatic tissues by reverse transcription and polymerase chain reactions (RT-PCR). PCR-generated human KGF complementary DNA (cDNA) clone was confirmed by restriction enzyme digestion analysis and partial DNA sequencing. Expression of KGF in archival canine benign prostatic hyperplastic tissues was also examined. In a pilot experiment, RNAs isolated from formalin-fixed (FF) and formalin-fixed and paraffin-embedded (FFPE) canine prostatic tissues were shown to be of sufficient quality to permit amplification of KGF mRNA by RT-PCR. The transcript of a housekeeping gene, glucose-6-phosphate dehydrogenase (G6PD), was detected by RT-PCR indicating the quality of RNAs to be more than adequate for RNA expression analysis. Later, total RNA from two archival canine FF prostate tissue types, benign prostatic hyperplasis and mild glandular hyperplasia, were used to amplify canine KGF transcripts. Southern hybridization analysis using rat and human KGF cDNAs as probes confirmed the fidelity of the amplified PCR product and it was indeed canine KGF.

Animals↗

PubMed1994

Depression of developing neuromuscular synapses induced by repetitive postsynaptic depolarizations.

Effect of postsynaptic activity on the synaptic efficacy was studied in Xenopus nerve-muscle cultures. Repetitive postsynaptic depolarizations induced by injection of current pulses into singly innervated myocytes resulted in significant reduction in the frequency of spontaneous synaptic currents and the amplitude of nerve-evoked synaptic currents at the majority of synapses that showed immature synaptic properties. Repetitive hyperpolarizations and steady depolarizations of similar duration were without effect. The depolarization-induced synaptic depression appeared to result predominantly from a reduced ACh secretion from the presynaptic nerve terminal. Buffering the myocyte cytosolic Ca2+ at a low level with intracellular loading of a Ca2+ buffer, 1,2-bis(2-aminophenoxy)ethane-N,N,N',N'-tetra-acetic acid (BAPTA), significantly reduced the effect of the depolarizations. Thus postsynaptic electrical activity can regulate the synaptic efficacy of the developing neuromuscular synapases and the regulation may be mediated by retrograde transsynaptic interactions.

Action Potentials↗

PubMed1994

Diving pattern of fishermen in the Pescadores.

Professional diving fishermen in the Pescadores Archipelago (119.30 degrees W, 23.30 degrees N) dive with a simple hookah system. Although they use modern equipment, such as wet suit, face mask, mouth piece with demand valve, spear gun, weight belt, and fins, their lack of knowledge of diving medicine is apparent. On the average, 180 cases of decompression sickness (DCS) per year were reported to occur in the Pescadores. We conducted studies in 1990 and 1992 on three islands of the Archipelago. At the time of our study, an estimated 140 diving fishermen resided on these three islands. Of the 62 fishermen interviewed, 14 volunteered for the recording of dive profiles using a diver-carried data logger. In the summer of 1990, a group of eight fishermen dived, on the average, to a depth of 17.8 +/- 5.3 m (mean +/- SD; range, 8-27 m) for 26.9 +/- 19.7 min (5-66 min). Although the diving depth was similar to that of the average recollections of 43 divers, 20.1 +/- 4.4 m (15-30 m), the actual diving time was far shorter than that of their recollections, 426 +/- 138 min (240-630 min). The post-typhoon sea floor conditions may have shortened their diving time. In the summer of 1992, a group of six fishermen dived to 20.5 +/- 3.8 m (15-26 m) for 56.4 +/- 21.2 min (18-84 min). Again, the diving depth matched that of their recollection well, 22.2 +/- 2.5 m (20-26 m), but their bottom time was far shorter than they believed, 270 +/- 108 min (120-480 min). They used no decompression procedures, regardless of the bottom time and diving depth. In the 1990 group, 5 out of 10 equivalent single dive bottom times (ESDBT) exceeded U.S. Navy no-decompression (No-D) air dive limits; whereas in the 1992 group, 7 out of 9 ESDBTs exceeded No-D limits. Eight of the 38 discrete dives exceeded the No-D limits, even if we underestimate their decompression stress by disregarding their repetitive dive history. However, no symptoms of DCS were observed in either the 1990 or 1992 groups of 14 divers, despite 63% of the ESDBTs and 21% of discrete dives having exceeded the No-D limits. Adaptation to diving work may have allowed them to exceed the established No-D limits. The existing records of incidence of DCS from this region suggest that previously they must have dived longer or deeper or both during times of abundant resources.

Adult↗

PubMed1994

Distribution and response evoked by microstimulation of thalamus nuclei in patients with dystonia and tremor.

The effect of 806 microstimulations were observed in 16 patients with movement disorders, dystonia (DA, n = 6) and tremor (TR, n = 10). Among the 347 sites in DA patients motor response was seen at 29 sites, the response with increased dystonia was seen at 28 sites. The effect could be seen at 14 sites (50%) in ventrointermedialis (Vim), five sites (18%) in ventrocaudalis (Vc) and five sites (18%) in white matter (Wm). As for the other four sites, one site was in ventraloralis anterior (Voa), two sites in ventraloralis posterior (Vop), and one site in dorsal thalamus (dth), but reduction of dystonia drive was only seen at one site in dth. On the other hand, among the 459 sites in TR patients, motor response leading to reduction of tremor drive was seen at 38 sites, of which 30 sites (79%) were noted in Vim nuclei, and five sites (13.2%) in vc nuclei; of the remaining sites, two were seen in Vop nuclei, one in dth, and no increasing tremor drive was observed in all area. In general, paresthesia was the most common response, which was found at 159 sites (45.8%) with DA and 216 sites (47.1%) with TR. Pain was only seen at one site in Wm of DA; warm/cold and vertigo could be seen in Vop, Vim, and vc nucleus respectively. No responses were shown at 156 sites (45%) in DA, and 201 sites (43.8%) in TR.

Dystonia↗

PubMed1993

Neurons in the area of human thalamic nucleus ventralis caudalis respond to painful heat stimuli.

A population of neurons in the area of human thalamic nucleus ventralis caudalis (Vc) respond to noxious heat stimuli. In the cutaneous core of Vc 6% (6/108) of recorded neurons had a significantly greater response to noxious heat stimuli than to innocuous control stimuli. Half of these neurons (n = 3) also responded to innocuous cold stimuli. Within the region posterior and inferior to the cutaneous core of Vc 5% (4/77) of neurons responded exclusively to noxious heat stimuli. Cells responding to noxious heat were recorded at a greater proportion (66%) of sites where painful sensations were evoked by microstimulation than at sites where nonpainful sensations were evoked (1.5%). The results suggest that neurons in the region of human Vc mediate the sensory aspect of pain.

Electric Stimulation↗

PubMed1993

Biosynthesis and secretion of growth factor proteins by kidney cells from DES-treated Syrian hamsters.

Long-term estrogen treatment of Syrian hamsters results in the initiation and development of hormone-dependent renal adenocarcinomas. The pathway(s) to neoplastic transformation remain unknown in this animal model of hormonal carcinogenesis. In the present study, short-term primary kidney cell cultures and incubations of freshly prepared kidney slices have been incubated with [35S]-methionine to study the effects of estrogen treatment on protein biosynthesis in the Syrian hamster. An increase in amount of two secreted proteins were observed with an increasing duration of diethylstilbestrol (DES) treatment. Further characterization of these proteins by two-dimensional electrophoresis identified two proteins present only in treated hamsters, a 20-22 kDa protein and a 16-18 kDa protein with an isoelectric point of 8.5-9.0. Immunoprecipitation using specific antibodies to growth factors, followed by separation on SDS-PAGE electrophoresis, showed that kidney slices from five month-treated animals produced a TGF-alpha-like protein and a bFGF-like protein. The induction of these growth factors may play an important role in the tumorigenic process in kidneys of Syrian hamsters, including cell proliferation and vascularization of the tumor tissue.

Animals↗

PubMed1993

In vitro uptake and autoradiographic localization of tritiated gossypol in Taenia taeniaeformis metacestodes.

Gossypol, a natural polyphenolic compound, induces growth-inhibitory and antiparasitic effects in Taenia taeniaeformis metacestodes in vivo and in vitro. We investigated the uptake and localization of [3H]-gossypol in this parasite. Metacestodes were incubated in 10(-5) M [3H]-gossypol at 37 degrees C. Parasites steadily took up tritium activity over the first 3 h of incubation, after which a plateau was maintained for the duration of the experiment. Tissue: medium radioactivity ratios revealed that intralarval tritium activity matched extralarval activity within 30 min of incubation and continued to increase with time. Reverse-phase high-performance liquid chromatographic (HPLC) analysis confirmed tissue incorporation of tritium activity that manifested as a single radioactive species. Autoradiography localized [3H]-gossypol to the tegument, calcareous corpuscles, and parenchyma over the first 2 h of incubation. By 6 h, parenchymal radioactivity had disappeared. T. taeniaeformis metacestodes rapidly take up and accumulate [3H]-gossypol in vitro. This accumulation is apparently selective for specific sites, which may have implications for gossypol's metacestocidal action.

Animals↗

PubMed1993

Gossypol inhibits basal and estrogen-stimulated DNA synthesis in human breast carcinoma cells.

Estrogen stimulates the growth of hormone-dependent human breast cancer. Failure of chemotherapy frequently results from the development of multidrug resistance. Gossypol (GP), a naturally occurring toxin, inhibits the growth of various carcinoma cells. Thus, the effects of GP on 17 beta-estradiol (E2)-stimulated DNA synthesis were studied in two hormone-dependent human breast carcinoma cell lines: the wild-type MCF-7 and the multidrug-resistant MCF-7 Adr cells. Cells (5 x 104/well) were cultured for 24 hrs in a chemically-defined, serum-free medium consisting of 1:1 mixture of Dulbecco's Modified Eagle's medium and Ham's nutrient mixture F12 (DMEM/F12) supplemented with insulin (5.0 micrograms/ml), transferrin (5.0 micrograms/ml), epidermal growth factor (EGF; 10.0 ng/ml) and antibiotics E2 (0 or 10.0 nM), GP (0, 2.5, 5.0, 10.0 or 20.0 microM) and bovine serum albumin (BSA; 0 or 0.1 mg/ml) were used as treatments in a factorial experimental design. Cells were treated for 24 hrs and finally pulsed with 3H-thymidine (5.0 microCi/ml) for 3 hrs. E2 significantly stimulated 3H-thymidine incorporation in both MCF-7 and MCF-7 Adr cells. GP at 10.0 and 20.0 microM inhibited both basal and E2-stimulated DNA synthesis in human breast cancer cells. The inhibitory effects of GP at 10.0 microM, but not at 20.0 microM, were blocked by BSA treatment. Results from the present study indicate that GP treatment was antiproliferative in both drug-sensitive and multidrug-resistant cancer cells and that the antiproliferative effects of GP on human breast cancer cells were mediated through mechanisms independent of estrogenic responses. Thus, GP could be potentially very useful for treatment of human breast cancer patients, especially those who have developed multidrug resistance.

Breast Neoplasms↗

PubMed1993

Pregnancy can be established in superovulated adult rats treated with progesterone and an aromatase inhibitor.

An adult superovulated rat model has been developed and is characterized by high ovulation rates, early morphological degeneration of embryos, complete embryo loss within 48 hours of conception and elevated peripheral estradiol(E2)/progesterone(P4) ratios. In this study, three trials were conducted using the superovulated adult rat model. First, control naturally cycling rats were compared with superovulated rats supplemented with 1 mg P4 on days 0-3 of pregnancy. A sperm positive vaginal smear is designated as day 0 of pregnancy. The P4 treated rats demonstrated improved embryo retrieval on day 1 of pregnancy, continued embryo recovery with a decrease in normal morphologic characteristics of integrity on day 2, with nearly total embryo loss by day 3. On each day, P4 levels were elevated 2-3 times over control. The second trial compared 3 groups of rats, 1) naturally cycling, 2) superovulated unsupplemented and 3) superovulated rats supplemented with 1 mg P4/rat/day and the aromatase inhibitor, 4-hydroxyandrostenedione (4-OHA), 12.5 mg/rat/day. The superovulated unsupplemented rats had no embryo recovery after day 2 of pregnancy, while the P4 and 4-OHA treated rats showed a variable ability to maintain normally developing embryos through day 4 of pregnancy. E2 levels were elevated in both superovulated groups on days 1-4 of pregnancy as were P4 levels on days 2-4. The E2/P4 ratio was significantly lowered only on day 1 of pregnancy in the P4 and 4-OHA treated group. The third trial demonstrated implantation in 50% of the superovulated rats supplemented with P4 and 4-OHA. In conclusion, implantation in the superovulated adult rats can occur with P4 and 4-OHA supplementation, however, this biologic phenomenon could not be explained by obvious changes in peripheral E2 and P4 levels.

Analysis of Variance↗

PubMed1993

Acceleration of embryo transport in superovulated adult rats.

The etiology of reduced fertility in rodents and humans after exogenous gonadotropin-induced superovulation is unknown. This study examines implantation failure in adult rats induced to superovulate by gonadotropin treatment. After multiple injections of pregnant mare serum gonadotropin (PMSG) followed by human chorionic gonadotropin (hCG), superovulation in adult rats was confirmed on day-1 of pregnancy, however, on day-13, no implantation sites were observed. Daily flushing of oviducts and uteri revealed that the number of embryos recovered from superovulated rats on day-2 was only one-third of that retrieved on day-1. The numbers of embryos retrieved on these days from the oviducts of control rats, however, were almost equivalent. On day-3, no embryos were retrieved from either the oviducts or uteri of superovulated rats, while all embryos from control rats were found in the oviducts. Most embryos recovered from superovulated rats showed normal development. Compared to levels in control rats, serum estradiol (E2) in superovulated rats increased significantly on days-2 and -3 of pregnancy, whereas, serum progesterone (P) levels remained unchanged. Thus, E2/P ratio increased on days-2 and -3 of pregnancy in superovulated adult rats coinciding with the timing of embryo transport acceleration. Our results suggest that superovulated oocytes can be fertilized and reach an early stage of development within the oviduct. Implantation failure in superovulated rats may be due to the accelerated embryo transport resulting from elevated E2/P ratio.

Animals↗

PubMed1993

Transforming growth factor-beta(1) regulates differentiation of porcine granulosa cells in vitro.

Transforming growth factor-beta (TGF-beta) is a potential regulator of ovarian function and follicular development. It is speculated that TGF-beta mediates the events in the follicle which culminate in ovulation of the oocyte. The complex processes which ultimately leads to this natural phenomenon must involve interactions between the 2 major follicular cell types, theca and granulosa cells, and the oocyte. Furthermore, a complex local regulatory system must exist to determine which follicles should undergo development and, eventually, which of those should ovulate or undergo atresia. To begin to understand this perplexing process, we must first understand the variables which control the function of each individual cell type. This study investigated the effect of TGF-beta(1) on FSH-induced porcine granulosa cell differentiation in vitro. Transforming growth factor-beta(1) was shown to inhibit progesterone production at high concentrations (0.1 and 10.0 ng/ml) after 12-, 24- and 48-hour treatment. However, TGF-beta(1) produced a biphasic effect on FSH-induced progesterone production during the 12-hour interval between the 36- and 48- hour treatment periods; TGF-beta(1) stimulated progesterone production at a low concentration (0.001 ng/ml) and inhibited production at high concentrations (0.1 and 10.0 ng/ml). The results obtained from the biphasic effect were not observed during any of the other incubation periods or intervals investigated. These results show that TGF-beta(1) has opposing effects on the differentiation of porcine granulosa cells as compared with those on rat granulosa cells. Moreover, TGF-beta(1) can produce opposing effects within the porcine granulosa cell itself which are specific to the concentration and treatment period used. The results of this study seem to suggest that TGF-beta(1) is species- and time-specific in its regulatory actions on FSH-induced porcine granulosa cell differentiation.

Journal Article↗

PubMed1993

Effect of epidermal growth factor (EGF) and defined simple media on in vitro bovine oocyte maturation and early embryonic development.

The purpose of this study is to evaluate the effect of EGF and defined simple media on in vitro bovine oocyte maturation and early embryonic development. Bovine follicular oocytes were matured in vitro and co-cultured with frozen-thawed bull sperm, which was capacitated with Hepes buffered saline (HBS) solution. After incubation of oocyte-sperm complexes for 4 days, the cleavage rate was evaluated. The results obtained were as follows: 1) When bovine oocytes were matured and embryos were developed in Park-Lin medium 1 (PL(1)) containing fetal calf serum (FCS) or EGF + bovine serum albumin (BSA), the latter treatment was more effective in inducing embryonic cleavage (18%) than FCS alone (10%). 2) When bovine oocytes were matured in Park-Lin medium 2 (PL(2)) without EGF and the subsequent embryos were developed in PL(2) medium with EGF, the cleavage rate was 22.6%. 3) When bovine oocytes were matured in PL(2) medium with EGF and then the embryos were developed in PL(2) medium with EGF, the cleavage rate was 35.8%. 4) When bovine oocytes were matured in Park-Lin medium 3 (PL(3)) without EGF and then the embryos were developed in PL(3) medium, the cleavage rate was 50%. 5) When bovine oocytes and resulting embryos were matured in PL(3) medium with EGF, the cleavage rate was 53%. 6) The parthenogenesis rate induced by PL(3) medium in our current study was comparable to the findings reported by other laboratories. These results suggest that EGF stimulates in vitro bovine oocyte maturation and subsequently affects embryonic development. It is suggested that PL(3) medium is a better defined simple medium than the other media currently used by other laboratories for in vitro bovine oocyte maturation.

Journal Article↗

PubMed1993

Induction of chromatid breaks and tetraploidy in Chinese hamster ovary cells by treatment with sodium arsenite during the G2 phase.

Treatment of Chinese hamster ovary (CHO) cells with sodium arsenite during the G2 phase induced poorly condensed chromosomes and chromatid breaks. The induction of chromatid breaks was confirmed by the appearance of micronucleated cells after arsenite-treated G2 cells were allowed to re-enter interphase. When the duration of the G2 phase was artificially divided into 4 periods, more chromatid breaks were induced by treatment with arsenite during the very early G2 phase (or G2/S boundary). In addition to the induction of chromatid breaks, arsenite treatment also remarkably retarded the re-entry of mitotic cells into interphase. By replating and incubating arsenite-treated G2 cells in drug-free medium, we subsequently observed the appearance of a population of cells whose DNA content was between 4C and 8C, and metaphase cells with near-tetraploid chromosome numbers in the next mitotic division.

Animals↗

PubMed1993

Effect of ethanol and progesterone on monoamine oxidase activity in cultured cells of human term placenta.

OBJECTIVE: The aim of this study was to evaluate the effect of ethanol and progesterone on the monoamine oxidase activity in cultured human term placental cells. STUDY DESIGN: Human placental cells were prepared from normal human term placentas by enzymatic dispersion in Dulbecco's modified Eagle medium. The viability of placental cells prepared by our method was 90%, and the yield of placental cells was 0.6 x 10(6) cells per gram of wet placental tissue. Five milliliters of Dulbecco's modified Eagle medium containing 3 x 10(5) placental cells was plated in a 25 cm2 flask and cultured for 8 days in an incubator at 37 degrees C under an atmosphere of 5% carbon dioxide and 95% oxygen with a saturated humidity. During the culture period the culture medium was replenished every 2 days. A confluent monolayer condition was achieved after 8 days in culture. The cultured placental cells were treated with different concentrations of ethanol (0, 34.6, and 69.2 mmol/L) and progesterone (0, 16, and 32 mumol/L) on day 8 of culture for 48 hours. At the end of treatment placental cells from control and treated flasks were harvested for the analysis of monoamine oxidase activity by spectrophotometry. The effects of ethanol and progesterone on cultured placental cells were statistically analyzed by one-way analysis of variance followed by Duncan's multiple comparisons procedure. RESULTS: A human placental cell culture system has been established from normal human term placentas. The monoamine oxidase activity in 8-day-cultured human term placental cells was significantly higher than that of freshly prepared placental cells. Ethanol concentrations at 34.6 and 69.2 mmol/L significantly increased and progesterone concentration at 32 mumol/L significantly decreased the monoamine oxidase activity. CONCLUSION: These results suggest that the cultured human term placental cells can be used to examine the in vitro effects of ethanol and progesterone on monoamine oxidase activity. However, the physiologic significance of progesterone's inhibitory effect and the stimulatory effect of ethanol monoamine oxidase activity in the in vivo system have yet to be further investigated.

Cells, Cultured↗

PubMed1993

Decreased level of PDGF-stimulated receptor autophosphorylation by fibroblasts in mechanically relaxed collagen matrices.

The goal of our studies was to characterize the interrelationship between extracellular matrix organization and fibroblast proliferation in response to growth factors. We compared fibroblasts in monolayer culture with cells in contracted collagen matrices that were mechanically stressed or relaxed. In response to platelet-derived growth factor (PDGF), DNA synthesis by fibroblasts in mechanically relaxed collagen matrices was 80-90% lower than in monolayer culture and 50% lower than in mechanically stressed matrices. Fibroblasts in monolayer and contracted collagen matrix cultures contained similar levels of PDGF receptors, but differed in their autophosphorylation response. Cells in mechanically relaxed matrices showed lowest levels of autophosphorylation, 90% less than cells in monolayer culture. Experiments comparing receptor expression and capacity for PDGF-stimulated autophosphorylation showed that cells in mechanically relaxed collagen matrices never developed normal receptor autophosphorylation. Furthermore, when mechanically stressed collagen matrices were switched to mechanically relaxed conditions, capacity for receptor autophosphorylation decreased within 1-2 h and remained low. Based on immunomicroscopic observations and studies on down-regulation of receptors by PDGF binding, it appeared that most PDGF receptors in monolayer or contracted collagen matrix cultures were localized on the cell surface and accessible to PDGF binding. In related studies, we found that EGF receptors of fibroblasts in mechanically relaxed collagen matrices also showed low levels of autophosphorylation in response to EGF treatment. Based on these results, we suggest that mechanical interactions between cells and their surrounding matrix provide regulatory signals that modulate autophosphorylation of growth factor receptors and cell proliferation.

Cell Membrane↗

PubMed1993

Correlation of specific virus-astrocyte interactions and cytopathic effects induced by ts1, a neurovirulent mutant of Moloney murine leukemia virus.

ts1 is a highly neuropathogenic and lymphocytopathic mutant of Moloney murine leukemia virus TB (MoMuLV-TB). We previously reported that the primary neuropathogenic determinant of ts1 maps to a single amino acid substitution, Val-25-->Ile, in precursor envelope protein gPr80env. This Val-25-->Ile substitution apparently renders gPr80env inefficient for transport from the endoplasmic reticulum to the Golgi apparatus. These findings suggest that the cytopathic effect of ts1 in neural cells might be due to the accumulation of gPr80env in the endoplasmic reticulum. Since endothelial and glial cells are targets of ts1 infection in the central nervous system, we established primary endothelial and astrocyte cultures to investigate the mechanism of cell killing caused by ts1. A continuous cell line, TB, was used as a control. Our results showed that both ts1 and MoMuLV-TB replicated and induced a cytopathic effect in astrocyte cultures, albeit to different degrees; ts1 appeared to be more lethal than MoMuLV-TB. On the other hand, ts1 and MoMuLV-TB infections of endothelial or TB cells were not cytopathic. The cytopathic effect in infected astrocytes correlated with the inefficiency of gPr80env transport and the intracellular accumulation of gPr80env as well as aberrant virus particles.

Animals↗

PubMed1993

Thermal and pain sensations evoked by microstimulation in the area of human ventrocaudal nucleus.

1. We have studied the sensations evoked by threshold microstimulation (TMS) in the area of the human principal sensory nucleus of the thalamus [ventralis caudalis (Vc)] in patients (n = 11) undergoing stereotactic surgery for the treatment of movement disorders and pain. Preoperatively, patients were trained to describe somatic sensory stimuli using a standard list of descriptors. This same list was used to describe sensations evoked intraoperatively by thalamic microstimulation. Stimulation sites (n = 216) were defined by location within the area where the majority of cells had a reproducible response to innocuous cutaneous stimulation (core region) or in the cellular area posterior and inferior to the core region (posteroinferior region). 2. TMS-evoked sensations were categorized as paresthetic if the descriptors "tingle," "vibration," or "electric current" were chosen by the patient to describe the sensation and as thermal/pain if the descriptors "cool," "warm," "warm and cool," or "pain" were chosen. Thermal/pain sensations were evoked by stimulation in 82% (9/11) of patients and at 19% of sites studied. These results suggest that thalamic microstimulation can evoke thermal/pain sensations reproducibly across patients. 3. Thermal/pain sensations were evoked more frequently by stimulation at sites in the posteroinferior region (30%) than by stimulation at sites in the core region (5%). Nonpainful thermal sensations composed the majority of thermal/pain sensations evoked by stimulation in both the core (80%) and posteroinferior regions (86%). Sites where stimulation evoked pain and nonpainful cool sensations were found anterior to the area where nonpainful warm sensations were evoked. Thermal/pain sensations were evoked at sites located medially near the border between the core and posteroinferior regions. 4. Radiologic techniques were used to determine the presumed nuclear location of stimulation sites. Thermal/pain sensations were evoked less frequently by stimulation in the part of Vc included in the core region than by stimulation in any of the following: the part of Vc included in the posteroinferior region, ventralis caudalis portae nucleus, ventralis caudalis parvocellularis nucleus, or the white matter underlying the ventral nuclear group. 5. The location of the sensation evoked by stimulation [projected field (PF)] varied widely in size. PFs were categorized as large if they involved more than one part of the body (e.g., face and arm) or if they crossed at least one joint proximal to the metacarpophalangeal joint or to the metatarsophalangeal joint. PFs were more frequently large at sites where thermal/pain sensations were evoked by TMS (33%) than at those where paresthesia were evoked (6%).(ABSTRACT TRUNCATED AT 400 WORDS)

Brain Mapping↗

PubMed1993

Urinary N-acetyl-glucosaminidase excretion and environmental lead exposure. Green Cross Health Service Association Study Group.

To understand the relationship between chronic low-level lead exposure and renal function, residents living nearby a lead battery factory for more than 10 years were selected and entered in this cross-section study. The residents living in the 1st village, within 500 m from the factory, were grouped in group 1; those in the 2nd village, within 1,000-1,500 m, in group 2, and those in the 3rd village, far from any lead-contaminated sources, in group 3. Twenty-four-hour urinary N-acetyl-glucosaminidase (NAG) was detected as early indicator of renal damage, and an ethylenediamine-tetraacetic acid mobilization test was performed to estimate total body lead burden of lead-exposed persons. Blood lead level (BLL) showed a significant difference among the three study groups. The further the distance between the group and the factory, the higher BLL. The results showed a significant high prevalence of abnormal urine NAG excretion in the chronic lead-exposed group, although BLL and body lead burden of these persons were within the 'normal' range. A significant correlation between body lead burden less than 200 micrograms and 24-hour urine NAG excretion and a dose-response relationship between them were found. These observations suggested that lead was the possible cause of abnormal renal tubular function in persons with chronic low-level lead exposure, but this effect became blunt when body lead burden was more than 200 micrograms. The possible explanation may be that high body lead burden from long-term exposure will deplete the kidney of NAG or render it insensitive to the effects of lead exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylglucosaminidase↗