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Biomedical subjects

Y C Tong

Publications and source records attributed to Y C Tong.

At least 37 records · Page 2Linked to original sources
PubMed1996

The norepinephrine tissue concentration and neuropeptide Y immunoreactivity in genitourinary organs of the spontaneously hypertensive rat.

Tissue concentration of norepinephrine and neuropeptide-Y immunoreactivity (NPY-IR) were measured in the urinary bladder, urethra, prostate and corpus cavernosum of the spontaneously hypertensive rat, as well as the normotensive Wistar-Kyoto rat. The results showed significantly increased tissue norepinephrine concentrations in the urinary bladder, urethra and prostate of the spontaneously hypertensive rat when compared to those of the normotensive rat (hypertensive, n = 18: 18.3 +/- 2.1, 14.9 +/- 1.7, 22.6 +/- 2.3 vs. normotensive, n = 18: 11.2 +/- 1.9, 10.4 +/- 1.3, 16.7 +/- 2.4 nmol/g tissue, respectively, P < 0.05 in each case). No difference was noted in the cavernosal tissue (hypertensive, n = 18: 11.3 +/- 1.6 vs. normotensive, n = 18: 10.1 +/- 1.8 nmol/g tissue, P > 0.01). Correspondingly, tissue NPY-IR was significantly increased in the bladder, urethra and prostate tissue of the spontaneously hypertensive rat (hypertensive, n = 18: 39.7 +/- 5.6, 25.3 +/- 3.4, 31.5 +/- 2.8 vs. normotensive, n = 18: 27.4 +/- 3.1, 18.6 +/- 2.7, 24.2 +/- 3.2 pmol/g tissue, respectively, P < 0.05 in each case). Again, no significant difference was observed in the cavernosal tissue (hypertensive, n = 18: 15.9 +/- 2.2 vs. normotensive, n = 18: 14.8 +/- 2.6 pmol/g tissue, P > 0.01). It is therefore concluded that increased tissue concentration of norepinephrine and NPY-IR were present in the urinary bladder, urethra and prostate of the spontaneously hypertensive rat. The significance of such biochemical findings needs further investigation but may suggest increased sympathetic innervation or activity. On the contrary, no corresponding changes were observed in the corpus cavernosum of the hypertensive rat.

Animals↗
PubMed1996

Dark-cycle video surveillance of sexual performances of normal and diabetic rats.

Clinically, a 59% prevalence of impotence was reported among diabetic male patients. Neurological, vascular, endocrinologic and psychological factors are probably involved. Previous reports with the rat model found deterioration of sexual behavior and reproductive function caused by streptozotocin (STZ)-induced diabetes. The purpose of the present study was to develop the dark-cycle video recording methodology for the observation of rat sexual activities and to study the effect of STZ-induced diabetes on sexual performances of the rat. Adult male Wistar rats were rendered diabetic with intraperitoneal injection of STZ (60 mg/kg body weight). In the 4th week a diabetic rat or a control rat was caged with an adult ovariectomized female rat during the dark cycle. The female had been brought into behavioral estrus with intramuscular injection of 0.1 mg estradiol benzoate 3 days before and 1.0 mg progesterone 3 h before testing. Infrared-light-illuminated video recording was performed to evaluate the sexual performances. The mounting latency and frequency, intromission latency and frequency, the hit rate as well as the post-ejaculatory period of the diabetic rats were significantly deteriorated when compared with the controls (p < 0.05). However, the ejaculatory latency showed no significant difference between the two groups (p > 0.05). In conclusion, it has been demonstrated that with this methodology, behavioral studies on nocturnal animals like the rat can be carried out conveniently. It was shown that the sexual arousal mechanism and copulation-ejaculatory mechanism were both depressed in STZ-induced diabetic rats. The same study model can be used for further pathophysiological and pharmacological researches on the sexual behaviors of diabetic rats.

Animals↗
PubMed1996

Treatment effect of "ryu-wei-ti-huang-wan" (a Chinese herbal prescription) on the sexual performance of male rats with streptozotocin-induced diabetes.

The treatment effect of "ryu-wei-ti-huang-wan', a Chinese prescription composed of extracts from six plants, on diabetic impotence was evaluated in the present study. Adult male Wistar rats were divided into three groups: (1) rats rendered diabetic with a single intraperitoneal injection of streptozotocin (60 mg/kg body weight); (2) rats with streptozotocin-induced diabetes treated with a ryu-wei-ti-huang-wan powder preparation at a dose of 30 mg powder/kg body weight twice a day, and (3) control rats. A male rat was caged with an adult ovariectomized female rat during the dark cycle. Infra-red-light-illuminated video recording was utilized to evaluate the sexual performance. The diabetic rats exhibited depressed mounting activity and no intromission or ejaculation. After ryu-wei-ti-huang-wan treatment either for 1 day or 2 weeks, the diabetic rats showed significant improvement in mounting performance with preservation of intromission and ejaculation. No significant difference in the blood sugar level was noted between the treatment and non-treatment groups. In conclusion, the diabetic rats showed impairment in sexual arousal, erectile as well as ejaculatory functions. Ryu-wei-ti-huang-wan was effective in preserving these functions with a rapid onset. It is evident that the extracts exert the therapeutic effects not through a lowering of blood sugar. These substances are potentially useful in the clinical treatment of male diabetic impotence.

Animals↗
PubMed1996

Prognostic factors of primary transitional cell carcinoma of the upper urinary tract.

OBJECTIVES: We presented and analyzed our results in order to determine the relationship between patient survival and tumor grade and/or stage. In addition, a retrospective tumor DNA ploidy study was done to evaluate its possible role in predicting future tumor recurrence in the bladder. METHODS: A total of 112 patients with upper urinary tract transitional cell carcinomas (TCCs) were recorded at our hospital. Of these, 68 patients without concurrent bladder tumors (ages ranged from 36 to 80, mean 62.4 years; male:female = 1:1.2) were treated by nephroureterectomy and bladder cuff resection. They were followed up for 14-79 months (average 38.2 months). Eight (36.4%) of the 22 patients who had stage C or D tumors had received adjuvant systemic methotrexate, vinblastine, epirubicin, cisplatin chemotherapy after surgery. DNA flow cytometry using paraffin-blocked tumor specimens was performed on the tumors of 52 patients. RESULTS: Their pathologic stages and grades were 11 at stage 0, 15 at stage A, 20 at stage B, 14 at stage C, 8 at stage D; 9 of grade I, 41 of grade II, and 18 of grade III. Postoperatively, 13 patients (19.1%) subsequently developed bladder tumors with a latent period ranging from 2 to 37 months (average 14.9 months). The difference of the tumor DNA ploidy distribution pattern among tumors of high versus low stages and/or grades is not statistically significant (p > 0.05). Overall, the 5-year survival rates for patients with low- and high-stage tumors were 100 and 66.7%, respectively; for patients with grade I-II and III tumors they were 93.6 and 28.3%, respectively. CONCLUSIONS: Patient survival was mainly related to both tumor stages (p = 0.0037) and grades (p = 0.0001), rather than to tumor DNA ploidy. For patients with grade II upper urinary tract tumors, tumor DNA ploidy seems to provide no additional predictive value on subsequent tumor recurrence in the bladder.

Adult↗
PubMed1996

Evidence of nonadrenergic, noncholinergic contraction in rat urinary bladder by 1,1-dimethylphenylpiperazinium stimulation in vivo.

Nonadrenergic, noncholinergic (NANC) contraction has been demonstrated in animal urinary bladder. However, the exact nature of the NANC innervation is still unclear. 1,1-Dimethylphenylpiperazinium (DMPP), which generates action potentials in the cell body of the postganglionic neuron and causes neurotransmitter release (both acetylcholine and noradrenaline), was given intravenously (0.1-0.7 mg/kg) to 3-month-old female Wistar rats under anesthesia (n = 20). Intravesical pressure, heart rate and blood pressure of the rats were monitored on Gould polygraph. Monophasic dose-dependent contractile response was observed upon administration of DMPP in 12 of 20 rats. After total adrenergic and cholinergic blockade with atropine, guanethidine, phentolamine and propranolol, the contractile response was reduced, not completely, in the animals. At the dose of 0.7 mg/kg, the contraction was reduced to about 48% of the original response. The study provides in vivo evidence for NANC contraction in the rat urinary bladder, moreover, the neurotransmitter is released from the postganglionic neurons.

Action Potentials↗
PubMed1995

Responses of dorsal cochlear nucleus single units to electrical pulse train stimulation of the auditory nerve with a cochlear implant electrode.

In response to 100-ms duration electrical stimulation within the range 50-400 pulses per second (pps), and at 1.6- to 2.4-mA stimulus current, a range of poststimulus time histogram (PSTH) patterns were observed from dorsal cochlear nucleus (DCN) units, they were usually primarylike, onset or "negative response" and occasionally buildup or pauser patterns. It appeared that the excitatory and suppressive processes, also termed neural drives, in response to 2.5-pps electrical stimulation were the main determinants of DCN unit responses to 50- to 400-pps stimulation. This was demonstrated by a model of DCN responses to electrical stimulation of the auditory nerve. The neural drives required to model the PSTH patterns were (i) an excitatory process with a latency of < 5 ms, (ii) a second excitatory process latency of 4.5-10 ms, (iii) a long acting suppressive process with a latency of < 15 ms and a duration of > 70 ms, (iv) a short acting suppressive response with a latency of 2.5-3.7 ms and a duration usually < 5 ms, but always < 20, and (v) a drive contributing spontaneous activity to the unit. In addition to these processes which were observed at 2.5 pps, an additional, transient suppressive process was postulated to operate only at 50-400 pps. It was postulated that the PSTH patterns observed were due to differences in the strengths of these drives between units.

Animals↗
PubMed1995

Effects of pregnancy and progesterone on autonomic function in the rat urinary bladder.

Previous studies have shown that pregnancy is associated with a decrease in cholinergic function in the rabbit urinary bladder. The present study aimed at evaluating the effects of pregnancy on the autonomic function of the rat urinary bladder and to elucidate whether progesterone is responsible for such alterations. Female Wistar rats, 3 months old, were divided into four groups: (1) 2-week pregnant rats; (2) rats given daily intramuscular injections of progesterone 5 mg/kg for 2 weeks; (3) rats given intramuscular injections of vehicle for 2 weeks, and (4) controls. Cystometry showed a significant increase in bladder capacity in the pregnant rats. The wet weight of the pregnant rat bladder was also significantly increased. Histologic study revealed increased bladder wall thickness with interstitial edema and urothelium proliferative changes to a papillary configuration in these pregnant bladders. Bladder muscle strip study showed significantly reduced maximum contractile responses to acetylcholine and methoxamine in the pregnant and the progesterone groups. Muscarinic receptor binding study demonstrated reduced Bmax in the pregnant rats and rats receiving progesterone injections (control group Bmax = 57 +/- 11, pregnant group Bmax = 44 +/- 8, p < 0.05; progesterone group Bmax = 40 +/- 7, vehicle group Bmax = 58 +/- 9 fmol/mg protein, p < 0.05). The contractile response to lower concentrations (10(-6) mol/l to 10(-4) mol/l) of ATP was elevated in the pregnant rats.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1995

Effect of alpha-chymotrypsin on the nonadrenergic, noncholinergic contraction of the rat urinary bladder in vitro.

The role of peptides in mediating the nonadrenergic, noncholinergic (NANC) response of the rat urinary bladder was studied. Electrical stimulation of muscle strips from 3-month-old female Wistar rat urinary bladders in the presence of autonomic blockers (atropine 10(-6) mol/l, propanolol 10(-6) mol/l, phentolamine 10(-6) mol/l, and guanethidine 10(-6) mol/l) showed NANC contraction accounting for 60% of the maximum contractile responses at 40 Hz. Frequency-response studies showed that in the presence of alpha-chymotrypsin (2 U/ml, 30-min incubation), the NANC contractile responses to electrical stimulation at lower frequencies (3-10 Hz) were enhanced (p < 0.05; n = 9). However, no significant differences were observed at higher frequencies (20-40 Hz). With repetitive 4-Hz stimulation, alpha chymotrypsin caused a 19% increase in the NANC contractile response (p < 0.05; n = 8). It is postulated that the NANC response of the rat bladder smooth muscle is composed of an excitatory (contractile) and an inhibitory (relaxant) component. Some peptide(s) is/are responsible for mediating the inhibitory response.

Acetylcholine↗
PubMed1995

Correlation of transrectal ultrasonographic findings of the prostate with the occurrence of detrusor instability in patients with benign prostatic hyperplasia.

Forty patients with benign prostatic hyperplasia were evaluated with urodynamics and transrectal ultrasonography. Seventeen patients were found to have detrusor instability while the remaining 23 did not. No significant differences were noted during ultrasonography in the estimated prostatic volume, the presumed circle area ratio and the incidence of finding prostatic calcification between these two groups. However, the incidence of detecting intravesical protrusion of the prostate is significantly higher in patients with instability than in patients with stable bladder (53 vs. 13%, p < 0.01). It is therefore postulated that intravesical protrusion may increase afferent impulses from the prostate and alter the stability status of the urinary bladder.

Aged↗
PubMed1995

Model of discharge rate from auditory nerve fibers responding to electrical stimulation of the cochlea: identification of cues for current and time-interval coding.

A model of the response of auditory nerve fibers to electrical stimulation of the cochlea is presented. Auditory nerve fiber responses are described in terms of cochlear regions activated by the stimulus: region A, in which the discharge rate equals a value of the pulse rate plus spontaneous activity, and region B, in which the discharge rate is less than pulse rate plus spontaneous activity but greater than spontaneous activity. The cues for intensity and time-interval coding provided by regions A and B are discussed.

Auditory Pathways↗
PubMed1995

Discharge rate-level functions from dorsal cochlear nucleus single units in response to acoustic and electrical stimulation of the auditory nerve.

Discharge rate-level (I/O) functions possessed by dorsal cochlear nucleus (DCN) units were examined, in response to bipolar electrical stimulation of the cochlea of the barbiturate-anesthetized cat. Spontaneously active units usually possessed nonmonotonic functions with a minimum, and spontaneously inactive units usually possessed monotonic functions or nonmonotonic functions with a maximum (NM+). In response to acoustic high-pass filtered noise, the function relating discharge rate and cutoff frequency resembled the same unit's I/O function to electrical stimulation. The I/O functions to acoustic characteristic tones were usually monotonic or NM+. These results suggest that in the DCN, a prerequisite for the generation of acoustic-like responses with an electrical stimulus may be the matching of the cochlear place and spatial extent activated by each stimulus.

Acoustic Stimulation↗
PubMed1994

Neural processes in the dorsal cochlear nucleus of the anaesthetised cat investigated from unit responses to electrical stimulation of the auditory nerve.

Extracellular responses of dorsal cochlear nucleus single units were recorded in response to biphasic, bipolar electrical stimulation of spiral ganglion cells and their peripheral processes using a banded electrode array in the scala tympani of the barbiturate anaesthetised cat. The DCN responses to this stimulus were the result of excitatory and suppressive (including inhibitory) processes. The excitatory responses from DCN units were usually within a range of 1.8-2.8 ms and these responses were probably the result of monosynaptic input from the auditory nerve. Latencies > 2.8 ms were most likely due to activation of di- and poly-synaptic pathways from auditory nerve fibres, except that latencies between 3.5-4.75 in hearing animals could have arisen from electrophonic mechanisms. Suppression of spontaneous activity was usually long acting, lasting > 70 ms following each pulse of the pulse train, but short acting suppression with a latency of 3.5-4.75 ms and a duration of < 10 ms was occasionally observed. These suppressive responses probably resulted from synaptic inhibitory input, but neural membrane properties may have contributed. In hearing animals, excitatory latencies within the range 1.8-5.2 ms were similar for units with different response area types or different PSTH patterns in response to acoustic CF tones or noise.

Acoustic Stimulation↗
PubMed1993

Electrode position, repetition rate, and speech perception by early- and late-deafened cochlear implant patients.

Psychophysical and speech perception studies were conducted on eight patients using the 22-electrode cochlear implant manufactured by Cochlear Pty. Ltd. Four early-deafened patients became deafened at 1-3 years of age and were implanted at 5-14 years of age. Four late-deafened (postlingual adult) patients became deafened at 38-47 years of age and were implanted at 42-68 years of age. Psychophysical studies measured the discrimination of trajectories with time-varying electrode positions and repetition rates. Speech perception studies measured performance using two speech coding strategies: a multi-electrode strategy which coded the first and second formant frequencies, the amplitudes of the two formants, and the fundamental frequency; and a single-electrode strategy which coded the amplitudes of the first and second formants, and the fundamental frequency. In general, the four late-deafened patients and one early-deafened patient were more successful than the other three early-deafened patients in the discrimination of electrode position trajectories and in speech perception using the multi-electrode strategy. Three of the four late-deafened patients were more successful than the early-deafened patients in the discrimination of repetition rate trajectories. Speech perception performance in the single-electrode strategy was closely related to performance in repetition rate discrimination. The improvement in speech perception performance from the single-electrode to multi-electrode strategy was consistent with successful performance in electrode discrimination.

Acoustic Stimulation↗
PubMed1993

Psychophysical and speech perception studies: a case report on a binaural cochlear implant subject.

Further improvements in speech perception for cochlear implant patients in quiet and in noise should be possible with speech processing strategies using binaural implants. For this reason, presented here is a series of initial psychophysical and speech perception studies on the authors' first binaural cochlear implant patient. For an approximate matching of the places of stimulation on the two sides, the patient usually reported a single percept when the two sides were simultaneously stimulated. Lateralization was strongly influenced by amplitude differences between the electrical stimuli on the two sides, but only weakly by interaural time delays. Speech testing, comparing monaural with binaural electrical stimulation, showed a binaural advantage particularly in noise.

Adult↗
PubMed1993

The perception of temporal modulations by cochlear implant patients.

The perception of temporal modulations of pulsatile electric stimuli was measured in seven cochlear implant patients using the Cochlear Pty. Limited prosthesis. Four patients were postlingually deafened adults and three patients were young adults who were deafened very early in life. The first study measured detection thresholds for modulated pulse duration for a series of modulation frequencies and pulse rates. The shape of the detection thresholds as a function of modulation frequency, the temporal modulation transfer function, often resembled a low-pass filter with a 50-100-Hz cut-off frequency. Thresholds did not markedly vary across the different pulse rates for most patients. Thresholds were less than 10%-20% of the range of usable hearing for most patients. The second study compared detection thresholds for modulated pulse durations around different reference pulse durations: 50, 100, and 300 microseconds. Detection thresholds were generally proportional to the different reference pulse durations. The third study measured difference limens for the discrimination of modulation depth. The difference limens were similar to the detection thresholds for the same reference pulse duration and pulse rate. The three patients deafened very early in life showed more within-group variation in performance, and their overall levels of performance were poorer than those of the postlingually deafened adults.

Acoustic Stimulation↗
PubMed1993

Evaluation of expandable leadwires for pediatric cochlear implants.

The development of cochlear implants for use in very young children (1-2 years old) will require techniques designed to accommodate temporal bone growth. Previous anatomic studies have shown that the leadwire of a cochlear implant must be capable of expanding up to 20 mm between the round window and the implanted receiver-stimulator in response to skull growth. In the present study morphologic and biomechanical evaluation of five expandable leadwire designs was conducted following their implantation in young cats. Two helical shaped leadwire designs frequently exhibited extensive fibrous tissue adhesions and broke during long-term implantation. In contrast, thin, flexible Silastic envelopes were effective in minimizing tissue adhesions. Residual V- and Z-shaped leadwires, placed in these envelopes, showed little evidence of fibrous tissue adhesions following implantation periods of up to 2 years. Moreover, these leadwires readily expanded both during the growth of the animal and when biomechanical expansion studies performed at the completion of the implant period. These expandable leadwire designs appear to be appropriate candidates for use in pediatric cochlear implants.

Animals↗
PubMed1992

Effects of acute in vitro overdistension of the rabbit urinary bladder on DNA synthesis.

Urinary bladder outflow obstruction induces a myriad of structural and functional changes in the organ. Among the morphological responses to outlet obstruction is both hyperplasia and hypertrophy of specific cellular elements. The initial event which has been implicated in the initiation of the response to outflow obstruction is an initial period of high intravesical pressure and subsequent distention of the bladder. In a previous study, it was shown that at one day following partial outlet obstruction there was a marked increase in thymidine labelling of the urothelium, at 3-5 days, the labeling shifted from the urothelium to the interstitial and serosal elements. The current study was designed to determine if acute distention of the urinary bladder can induce an increase in DNA synthesis (3H-thymidine incorporation), and localize the increased DNA synthesis via autoradiography of 3H-thymidine. In this study, the bladders of adult male New Zealand white rabbits were mounted in isolated in vitro baths. Each control bladder was filled to either 5 or 20 ml. with saline, or distended to 120% of capacity. The bladders were incubated for 7 hours at which time 3H-thymidine was placed both within and outside the bladder for an additional one hour. At the end of the time the bladder was divided at the ureteral orifices into bladder body and base, and each body and base divided into two sections. One section of bladder body and base was quantitatively analyzed for both labelled and unlabelled DNA; the second section was fixed and prepared for autoradiography. The results can be summarized as follows: 1) Acute overdistention for 8 hours induced a slight decrease in the DNA concentration which was mediated by edema of the bladder wall. 2) Acute overdistention induced a 5-fold increase in 3H-thymidine incorporation in the bladder body and a 3-fold increase in the bladder base. Radioautoradiography of the overdistended bladders showed significant and substantial labelling which was confined to the urothelial basal cells. The control bladders showed little or no labelling. These results are consistent with the theory that acute distention following partial outlet obstruction initiates the proliferative response of the bladder to outlet obstruction, and the urothelium is the initial target of the proliferative response. Functionally, the proliferative response may serve to maintain the structural as well as functional integrity of the bladder.

Animals↗