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Biomedical subjects

M T Chen

Publications and source records attributed to M T Chen.

At least 19 recordsLinked to original sources
PubMed1992

Elicitation of penile erection following activation of the hippocampal formation in the rat.

We explore the possible involvement of the hippocampal formation in penile erection, using male, adult Sprague-Dawley rats that were anesthetized with pentobarbital sodium. The intracavernous pressure (ICP) was used as the experimental index for penile erection. Electrical activation of the hippocampal formation resulted in two patterns, viz, multiple and single episodes of elevation in ICP, along with visible penile erection and ejaculation. The former pattern exhibited an increase in ICP that was more sustained, with higher peak amplitude and longer latency. Furthermore, they originated respectively from the granule cells of the dentate gyrus and pyramidal cells of the CA1 and CA3 fields of the Ammon's horn. Chemical stimulation of the hippocampus with glutamate also elicited significant increase in ICP. These results thus provided direct evidence to establish that the hippocampal formation may be involved in central neural regulation of the erectile process.

Animals↗
PubMed1992

Sonographic measurement of penile erectile volume.

For more accurate determination of the penile erectile volume in the flaccid and erectile states, and the difference between them, 20 impotent patients from 36 years old to 70 years old were enrolled in the study. Penile Doppler ultrasonography was performed to check the diameter of each corpus cavernosum, and diameter and peak flow velocity of each cavernous artery before and after intracavernous injection with 10 micrograms to 20 micrograms prostaglandin E1 (PGE1). The penile length was measured from base to midglans manually before and after PGE1 injection. The erectile volume in flaccid and erectile states was calculated as pi r2 x length. The summation of erectile volume of left and right corpus cavernosum was taken as the total erectile volume. The patients were classified into good (10 patients) and poor (10 patients) response groups based mainly on the mean peak flow velocity of both cavernous arteries greater or less than 25 cm/s. There was a significant increase of erectile parameters (penile length, diameter of corpus cavernosum, and total erectile volume) after PGE1 injection in each group of patients. For the total of 20 patients, the mean increase of penile length was 4.27 cm (80.0%), the diameter of corpus cavernosum was 0.66 cm (77.9%), and total erectile volume was 27.87 mL (459.0%). A comparison of the increase of penile erectile parameters after PGE1 injection between the good and poor response groups of patients revealed a significantly greater increase of the diameter of corpus cavernosum in the good response patients.

Adult↗
PubMed1992

Cisplatin-based chemotherapy for the treatment of advanced transitional-cell carcinoma of the urinary tract--a preliminary report.

The CMV (cisplatin, methotrexate, and vinblastine) and M-VAC (methotrexate, vinblastine, doxorubicin, and cisplatin) regimens were used to treat 19 patients with advanced transitional-cell carcinoma (TCC) of the urothelial tract. In the CMV group, the partial response rate was 45.5% and the mean response duration was 6.3 months. No complete response was obtained in our series. The median duration of survival was 15.8 and 8.3 months in responders and nonresponders, respectively. The toxic symptoms included one case of sepsis and three cases of renal toxicity. However, nausea and vomiting were experienced by most patients and required the administration of antiemetics. In the M-VAC group, the median duration of survival for responders was longer than that of nonresponders (greater than 10.2 vs 7.2 months), although the number of patients was too small for this difference to reach statistical significance. The toxic symptoms included one case of sepsis, two cases of renal toxicity, and nausea and vomiting in most patients. Bone metastasis in three patients did not respond to chemotherapy (CMV), a finding that is compatible with the results reported by other investigators. In summary, chemotherapy with the CMV or M-VAC regimen was effective in improving the response rate of patients. However, the duration of response was short, toxicity was severe in some cases, and the efficacy against bone lesions was poor. These problems must be solved to improve the outcome of patients with TCC following chemotherapy with the CMV or M-VAC regimens.

Adult↗
PubMed1992

Supernumerary nostrils.

We encountered a rare case of four asymmetrical nostrils 10 years ago. The upper nostrils looked normal while the lower appeared as sinuses. The lower pair communicated with the nasal cavities but the upper pair was obliterated. There was a thick columella and an elongated continuous nasal septum separating the nasal cavities. The left nostril sill was thicker and situated higher than its counterpart. When the patient was 3 months old, the lower sinuses were trimmed and closed primarily, while the upper pair was perforated and kept patent with a silicone tube covered with a split thickness skin graft. Four years later, a revision was performed. Stages of operation were preferred as nasal growth was concerned. The result was satisfactory following 10 years of observation.

Follow-Up Studies↗
PubMed1992

Effects of high fat-feeding to rats on the interrelationship of body weight, plasma insulin, and fatty acyl-coenzyme A esters in liver and skeletal muscle.

Rats fed a high-saturated fat diet consumed more energy, gained more weight, and displayed hyperinsulinemia (P less than .05) without an elevation in the fasting plasma glucose level, compared with animals on two different high-carbohydrate diets. The total fatty acyl-coenzyme A (CoA) concentration was 18% (P less than .0001) and 46% (P less than .0001) higher in liver and skeletal muscle, respectively, from rats fed the high-fat diet compared with each of the other diet groups. Major long-chain fatty acyl-CoA molecular species of both tissues in high fat-fed rats reflected the fatty acid profile of the diet. Approximately 29%, 21%, and 16% of total liver and skeletal muscle fatty acyl-CoAs were comprised of oleoyl-CoA, palmitoyl-CoA, and stearoyl-CoA, respectively. The amounts of these three fatty acyl-CoA esters were significantly higher in liver and skeletal muscle after high-fat feeding than with the other diet treatments (P less than .0001). In contrast, the concentration of linoleoyl-CoA was lower in both tissues after high-fat feeding (P less than .0001). In rats fed the high-fat diet, plasma insulin levels were significantly correlated with gain in body weight or body weight (r = .80, P less than .001 for insulin and gain in body weight; r = .73, P less than .001 for insulin and body weight). Total fatty acyl-CoA ester content in liver and skeletal muscle was also strongly correlated with the plasma insulin concentration in high fat-fed rats (r = .80, P less than .001 for liver; r = .78, P less than .001 for skeletal muscle).(ABSTRACT TRUNCATED AT 250 WORDS)

Acyl Coenzyme A↗
PubMed1992

Correlation of contractile function and passive properties of rabbit urinary bladder subjected to outlet obstruction--an in vitro whole bladder study.

The present study investigated the correlation between contractile function and passive properties of rabbit urinary bladder subjected to outlet obstruction. Mild bladder outlet obstruction was induced by placing silicone rings (7 mm. diameter) around the bladder necks of male New Zealand rabbits. The animals were sacrificed after 2 weeks of obstruction. Contractile function was evaluated by measuring the response of the in vitro whole bladder to 500 microM bethanechol administration. Passive properties was assessed by performing in vitro cystometry and stress-relaxation techniques utilizing six different infusion rates. When the intravesical pressure reached 30 cm. H2O the infusion was stopped, allowing the bladder to relax and intravesical pressure to drop to a steady state level. The results can be summarized as follows: 1) Although the intravesical pressure response to bethanechol was about the same in control (13.3 cm. H2O) and obstructed (12.4 cm. H2O) bladder, the obstructed bladder emptied significantly less than control (20.4 vs 89.3%); 2) the results of the passive properties study showed that bladder stiffness was significantly higher at all infusion rates in the obstructed bladder, 3) the obstructed bladder showed significantly less relaxation after rapid stretching of the whole bladder by high speed fluid infusion; 4) histological examination of obstructed bladders revealed marked fibrous thickening of the serosal layer, interstitial fibrosis of the muscle layers, and hypertrophic and/or degenerative changes of the muscle fibers. In summary, 2 weeks after mild outlet obstruction of the urinary bladder the emptying ability, but not pressure generation, was reduced along with increased bladder stiffness and diminished capacity for stress-relaxation. Interstitial fibrosis and changing the properties of the smooth muscle cells might be involved in the functional impairment and deranged viscoelasticity of the urinary bladder after outlet obstruction.

Animals↗
PubMed1992

Acupuncture in the treatment of renal colic.

A prospective randomized study was performed to compare the effect of acupuncture and intramuscular Avafortan injection in the treatment of renal colic. Our results showed that acupuncture is as effective in relieving renal colic as Avafortan but it had a more rapid analgesic onset (3.14 +/- 2.88 minutes versus 15.44 +/- 7.55 minutes, p less than 0.05). Of the patients in the Avafortan group 7 (43.8%) had side effects, including skin rash in 3, tachycardia in 2, drowsiness in 1 and facial flush in 1. No side effects were noted in the acupuncture group. During 2 hours of observation acupuncture and Avafortan seemed to be ineffective in promoting stone passage. However, patients receiving Avafortan treatment were more likely to have paralytic ileus. In summary, acupuncture can be a good alternative for the treatment of renal colic.

Acupuncture Therapy↗
PubMed1992

Intracavernous pressure as an experimental index in a rat model for the evaluation of penile erection.

This report communicates our attempt to design a small animal model for the evaluation of penile erection, based on the pharmacological responses of cavernous tissues in the rat that resemble those of human subjects. Male adult Sprague-Dawley rats anesthetized with pentobarbital sodium were used in conjunction with papaverine and prostaglandin E1, two vasoactive drugs most commonly used in clinical management of impotence. Intracavernous administration of papaverine (0.05, 0.1, 0.02, 0.4 or 0.8 mg.) induced a progressive increase in intracavernous pressure that peaked at 0.4 mg. This effect was associated with visible penile erection that became conspicuous when accompanied by additional bursts of transient intracavernous pressure fluctuations. The duration of papaverine-induced increase in intracavernous pressure was significantly shortened by clonidine (15 micrograms, intracavernous). Injection of prostaglandin E1 (1, 2 or 4 micrograms) into the corpus cavernosum also elicited an elevation in intracavernous pressure, but the responses exhibited acute tachyphylaxis. By manifesting a response to papaverine and prostaglandin E1 that is similar to that in human, we conclude that the intracavernous pressure in the rat may represent a suitable index for the evaluation of penile erection in small laboratory animals.

Alprostadil↗
PubMed1992

Determinant role of testosterone in the pathogenesis of urolithiasis in rats.

By using an ethylene glycol-induced urolithiasis model, we assessed the role of testosterone in the pathogenesis of urolithiasis. The intact and castrated male and female rats were fed with 0.5% ethylene glycol in drinking water for four weeks. The renal excretions of oxalate, citrate and other electrolytes were measured, and the stone and crystal deposit were examined microscopically. The results showed that drinking a loading of 0.5% ethylene glycol for four weeks produced hyperoxaluria in all rats, but the intact male rats excreted more urinary oxalate than any other groups of rats. The ethylene glycol-fed rats exhibited hypocitraturia except the castrated male rats. However, urolithiasis occurred in intact male but not female rats. Castration in male rats fed with ethylene glycol dramatically decreased the incidence of renal stone from 71.4% (5/7) to 14.3% (1/7). On the other hand, there was still no renal stone formed in the oophorectomized female rats which received ethylene glycol treatment. These data indicate that serum testosterone level plays a determinant role in urolithiasis formation.

Animals↗
PubMed1992

Uninephrectomy enhances urolithiasis in ethylene glycol treated rats.

Uninephrectomy (uNX) usually induces compensatory hyperfunction of the remaining kidney in an attempt to preserve the homeostasis of body fluid composition. The present study used uninephrectomized Sprague-Dawley rats on a lithogenic diet (0.5% ethylene glycol, EG) to evaluate the influence on urinary stone formation and calcium oxalate crystal deposition of compensatory excretion of lithogenic substances in the remnant kidney. The results showed that there were no urinary stones or calcium oxalate crystal deposits in the intact or uNX rats fed a normal diet. In the EG feeding groups, the incidence of massive (grade 3) crystal deposits was significantly higher in the uNX rats (87.5%) than that in the intact rats (37.5%; P less than 0.05). The incidence of urinary stone formation was also higher in the uNX rats as compared to that of the intact rats, although the difference did not achieve statistical significance. The serum magnesium, phosphorus and creatinine increased significantly, whereas creatinine clearance (CCr), 24-hour urinary excretions of citrate, sodium, potassium and chloride decreased significantly in the uNX rats fed EG. These data indicate that uninephrectomy increases the vulnerability of the contralateral remnant kidney to urolithiasis and crystal deposition when the lithogenic risk factors are present. Furthermore, once the remnant kidney forms urolithiasis or massive calcium oxalate crystal deposits, the renal function is severely compromised.

Animals↗
PubMed1992

Diagnosis of venous leakage by 133Xe corporeal clearance after intracavernous injection of prostaglandin E1 in poorly responding patients.

133Xe corporeal clearance after intracavernous (IC) prostaglandin E1 (PGE-1) injection was assessed in detecting venous leakage (VL) in a group of impotent patients with poor clinical response to PGE-1 injection. 133Xe corporeal washouts were done in the flaccid state and at full erection or at 20 min after the IC injection of 20 micrograms PGE-1 in cases where no full erection occurred in sequence on two separate days. In each case, data were acquired in frame mode after intracorporeal injection on one side of the midline just behind the glans of 0.1 ml, namely, 1-2 mCi (34-74 MBq) 133Xe in saline for 20 min. A time-activity curve was generated from the region of interest (ROI) at the site of injection and a computer routine was used to calculate clearance half-time (T1/2) in min and flow rate (Q) in ml per 100 g tissue per min. The data of 20 patients with equivocal response to IC PGE-1 were analysed. Of them, 14 had venous leakage and six had no vascular impairment (NVI). Venous leakage was proved by Doppler analysis, cavernosography after PGE-1, and/or selective arteriography. Twelve of 14 patients with VL had enhanced 133Xe corporeal clearance after PGE-1 with a significant decrease in T1/2 (mean +/- S.D.) from 115.9 +/- 196.0 to 13.3 +/- 13.4 (P less than 0.05) and increase in Q from 2.1 +/- 2.2 to 7.5 +/- 5.6 (P less than 0.01). In contrast, all six patients with NVI had decreased 133Xe corporeal clearance.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1992

Laparoscopic ligation of internal spermatic vein.

Laparoscopic procedures have long been a standard form of treatment for gynaecological disorders but have only recently shown promise in the evaluation and treatment of urogenital diseases, such as pelvic lymphadenectomy. We performed laparoscopic ligation of the bilateral internal spermatic veins in 15 male pigs. The average operative time was 20 min and operative morbidity was minimal, comprising mild subcutaneous emphysema around the trocars. Engorgement of the spermatic vein proximal to the endoclip site was noted. There was no operative mortality. Laparoscopic ligation of the internal spermatic veins seems to be a feasible method for the treatment of varicoceles, especially bilateral lesions.

Animals↗
PubMed1992

Laparoscopic nephrectomy in a porcine model.

Laparoscopic nephrectomy was performed in 15 male pigs, the procedure was successful in 14. Extraction of the intact kidney through a 5-cm lower abdomen incision was done in 7 animals; complete destruction and evacuation of the kidney was accomplished by a round-knife suction device through a 1-cm port in another 7 pigs. Grossly, the specimen consisted of sausage-like tubular renal tissue and a small amount of tissue debris. Pathology revealed that the glomerular and tubular structures were well preserved, no interstitial hematoma could be found. Four ports were usually used, one 1-cm umbilical camera port, one 0.5-cm port for ureter traction, and two 1-cm working ports along the midclavicular line. All the pigs recovered uneventfully. The average operation time was 3 h 20 min. The application of endo-GIA (United States Surgical Corporation) for renal hilum reduced the operative time to 2 h 20 min. Complications included renal vein tear during endoclip application and cutting in the first case, mild subcutaneous emphysema in 2 cases. This first pig received exploratory laparotomy for the repair and ligation of the renal vein. No more major complications occurred with increasing experience. From this porcine experiment, we conclude that the combination of laparoscopy, a tissue destroyer and an endobag for the entrapment of kidney seem to be a promising technique for clinical nephrectomy.

Animals↗
PubMed1992

Construction of detubularized ileal neobladder after radical cystoprostatectomy.

In an attempt to improve the patient's quality of life, we performed construction of neobladder using detubularized ileum along with radical cystoprostatectomy in 3 male patients with invasive bladder cancer. The mean followup was 28.3 months (16-45 months). All 3 patients achieved continent urination through the natural urine pathway-urethra with a satisfactory urinary stream during the day, but only 2 of them could also obtain continence in the night. Urodynamic study of the ileal neobladder showed a low pressure (mean 15.3 cm water) and no involuntary pressure spikes in the neobladder. The maximal urethral closure pressure (mean 62.0 cm water) and functional profile length (mean 3.0 cm) were adequate. In addition, the maximal uroflow rate was good (mean 16.7 ml/sec). There was no reflux in any of our patients. The radionuclide renal function study revealed that the renal function was preserved after operation in all 3 patients. Neocystourethroscopy showed no tumor and no stricture at the ileourethral anastomotic site in our 3 patients. There was no complication related to the operation. No disturbances of nutrition or electrolytes were found in any patient. All 3 patients had a satisfactory quality of life after operation though one patient died of widespread metastasis 16 months after operation. In conclusion, construction of detubularized ileal neobladder may be one of the ideal surgical procedures for bladder substitution after radical cystoprostatectomy.

Aged↗
PubMed1992

Comparison of effective renal plasma flow (ERPF) and endogenous creatinine clearance (Ccr) in evaluation of the differential kidney function: an in vivo study.

Eleven patients with obstructive uropathy were inserted with a pigtail catheter either for urinary diversion, endopyelotomy or percutaneous nephrolithotomy. Differential kidney functions were obtained by single-sample technique with I-131 orthoiodohippurate (OIH) and separate endogenous creatinine clearance (Ccr). Good linear correlation was noted between effective renal plasma flow (ERPF) and Ccr (r = 0.84, p less than 0.005), but there was still some discrepancy between these two examinations, chiefly found in two severely obstructed kidneys. Determination of ERPF by I-131-OIH single-sample technique is a simple, rapid, inexpensive and relative accurate test to measure the differential kidney function. But if the ERPF is at extremely low level, further investigations such as sonography of kidney and separate endogenous creatinine clearance should be done to avoid unnecessary nephrectomy.

Adolescent↗
PubMed1992

Radionuclide renal function study in various surgical treatments of upper urinary stones.

We conducted a radionuclide renal function study using 131I-hippuran in 188 patients with upper urinary stones before and every 3 months to the maximum of 12 months after various surgical treatments. Of 28 patients with renal staghorn stone, 24 underwent anatrophic nephrolithotomy and 4 percutaneous nephrolithotomy (PCNL). Of 36 patients with renal pelvic stone, 15 received open pyelolithotomy, 16 received PCNL and 5 received extracorporeal shock wave lithotripsy (ESWL). Of 71 patients with renal calyceal stone, 48 underwent PCNL and 23 ESWL. Of 53 patients with ureteral stone, 41 received ureterolithotomy, 8 PCNL and 4 ureteroscopic extraction. The renal function study determined individual and total renal function in terms of effective renal plasma flow (ERPF) at unilateral and bilateral kidneys. The mean total ERPF decreased 3-6 months after anatrophic nephrolithotomy (377.4 +/- 121.8 vs. 308.8 +/- 105.4 ml/min) or PCNL (447.4 +/- 152.3 vs. 386.8 +/- 140.8 ml/min) for staghorn stone. The mean ERPF of the kidney on the operative side decreased significantly to an extent of 29.4% up to 6 months after anatrophic nephrolithotomy. The mean ERPF on operative side increased significantly to an extent of 18.3% up to 6 months after ureterolithotomy. In conclusion, among the upper urinary stones, the unilateral (operative side) and total bilateral renal function decreased 1, 3, and 6 months, respectively, after anatrophic nephrolithotomy. On the contrary, the renal function increased significantly on the operative side up to 6 months after open ureterolithotomy. There was no significant change of mean ERPF at the kidney on operative or non-operative side in other kinds of upper urinary stones and surgical treatment.

Adult↗
PubMed1992

[Laparoscopic orchiectomy for intraabdominal cryptorchism and varicocelectomy].

Laparoscopic procedures have recently been used in the evaluation and treatment of some urogenital diseases. A case of right intraabdominal cryptorchism associated with left varicocele was successfully treated by laparoscopic orchiectomy and ligation of the contralateral internal spermatic vein concomitantly. This new technology can be easily performed and has the advantages of less tissue trauma, easy application for bilateral lesions, and less patient morbidity. We consider laparoscopy is a promising method for the diagnosis and treatment of intraabdominal testis.

Adolescent↗