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Biomedical subjects

M T Chen

Publications and source records attributed to M T Chen.

At least 73 records · Page 4Linked to original sources
PubMed1994

Decreased blood flow and defective energy metabolism in the varicocele-bearing testicles of rats.

This study was designed to elucidate the hemodynamic and energetic changes of testicles in experimental varicocele. Partial ligation of the left renal vein was performed in 10 Sprague-Dawley rats to induce dilatation of the internal spermatic vein, and sham operation was performed in the other 10 age-matched Sprague-Dawley rats used as controls. Blood pressure and rectal temperature were maintained at a constant level. Testicular blood flow was detected by laser Doppler flowmeter on the day before surgery and 4 weeks after surgery, respectively. Concentrations of various adenine nucleotides were determined by high-performance liquid chromatography (HPLC). We found a significant decrease from 10.2 +/- 1.5 to 7.4 +/- 1.8 mlLD/min/100 g (p < 0.005) in testicular blood flow after inducing varicocele in the rats. The energy charge of adenine nucleotides of the varicocele-bearing rats was 0.62 +/- 0.07 which was significantly lower than the 0.73 +/- 0.02 of the control group (p < 0.005). These observations have, thus, led us to propose the hypothesis that impaired spermatogenesis may result from defective energy metabolism in the varicocele-bearing testicles of rats.

Adenine Nucleotides↗
PubMed1994

Prediction of lymphatic spreading in prostatic cancer by prostate-specific antigen and Gleason's score.

A total of 58 patients have undergone bilateral pelvic lymphadenectomy as a staging procedure for clinically localized adenocarcinoma of the prostate. Of these, 19 patients (33%) had pelvic lymph node involvement. When a cutoff value of 50 ng/ml was used, the preoperative prostate-specific antigen (PSA) value had a positive predictive value of 57% for pelvic lymph node metastasis. Of the patients with PSA < 20 ng/ml, only 1 (4%) had evidence of lymph node metastasis. None of the patients with well-differentiated tumor (Gleason 2-4) had lymphatic spreading. In contrast, 82% of patients with poorly differentiated tumor (Gleason 8-10) had positive pelvic lymph nodes. Those patients with high PSA (> or = 20 ng/ml) and high Gleason's score (> or = 8) had the highest incidence of nodal extension (90%).

Aged↗
PubMed1994

Separation of thoracopagus conjoined twins. A case report.

A pair of thoracopagus conjoined twins with a connection at the atrioventricular groove of both hearts and a huge conjoined liver were surgically separated. An aortopulmonary shunt was created for Twin B, a victim of complex congenital heart disease with hypoplastic right heart syndrome, who died 5 hours later. However, Twin A survived after prolonged endotracheal intubation and parenteral nutrition. He survived for 7 months, and went home, but finally died of sepsis. In reviewing 47 pairs of surgically separated thoracopagus conjoined twins, in 30 pairs of type A (Leachman's classification, completely separate hearts), 42 patients survived (70%); in 5 pairs of type B (atrial connection only), one patient survived (10%); in 9 pairs of type C (both atrial and ventricular interconnections), none survived; in 3 pairs of unknown type, 2 survived. Total survival rate of surgically separated thoracopagus conjoined twins was 47.9%. The survival rate was 38.2% in those operated in the neonatal period (n = 34) and 63.6% in those operated over 1 month of age (n = 44) (p = 0.016). In conclusion, thoracopagus conjoined twins are rare. Although its separation carries a high risk, especially in those with cardiac connection, this report confirmed that separation is still feasible under proper preparation and planning.

Electrocardiography↗
PubMed1994

The changes of ocular axial length and corneal curvatures after scleral buckling for retinal detachment.

As myopia plays an important role in the pathogenesis of retinal detachment, alterations of refractive components after scleral buckling procedures for retinal detachment may be an important factor for retinal redetachment. To find out the refractive change following retinal detachment surgery, we prospectively followed up the alterations of corneal curvature, and axial components (axial length, anterior chamber depth, lens thickness, and vitreous length) of 44 eyes of rhegmatogenous retinal detachment before and after operations. The procedures consisted of encircling scleral buckling (12 eyes) and segmental scleral buckling (32 eyes). All patients were followed for 6 months postoperatively. The corneal curvatures were measured with a keratometer, the axial length and axial components were measured with an A-scan ultrasonography. The methods and materials used in operation were recorded in detail to correlate with the refractive changes. The corneal curvature showed a trend to flatten early after operation (the 1st week), and gradually reversed to steepening. But, the difference was statistically significant only at the K2 (vertical meridian) in the 1st postoperative week and the K1 (horizontal meridian) in the 4th postoperative week. Lengthening of eyeballs were noted in the encircling group (12 eyes), but only the elongation in the 1st postoperative week was statistically significant. While in segmental buckling group, the axial length of the eyeballs was transiently shortened. The shortening was significant in the 2nd, 4th, and 6th week after operation. The reduction of eyeball's axial length was related to the shortening of vitreous length and shallowing of anterior chamber.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1993

Efficacy of in vitro stone fragmentation by extracorporeal, electrohydraulic, and pulsed-dye laser lithotripsy.

Fragmentation has become the standard therapy for urinary calculi in the modern era. Stone fragility as well as position and size are important for the determination of a treatment program. To compare the efficacy of stone fragmentation, seven kinds of human urinary calculi with known composition (calcium oxalate monohydrate and dihydrate, dibasic calcium phosphate, uric acid, struvite, calcium phosphate, and cystine) were treated by three fragmentation techniques commonly used, namely extracorporeal shock wave (SWL), electrohydraulic (EHL), and pulsed-dye laser lithotripsy. Uric acid, calcium oxalate dihydrate, and calcium phosphate stones could be destroyed easily by any of these methods. Struvite was soft but sticky and not easy to break into tiny particles. Both dibasic calcium phosphate and calcium oxalate monohydrate stones were resistant to the laser and EHL; SWL is the treatment of choice. For cystine stones, none of the treatments was satisfactory; SWL was the only way to break them into large pieces.

Calcium Oxalate↗
PubMed1993

Histopathological changes in Kock pouch.

To investigate whether tumour recurrence or histological changes occur in the Kock pouch, periodic endoscopy with biopsy of the pouch was performed in 15 patients 6 to 66 months after radical cystectomy and urinary diversion for invasive bladder cancer. Endoscopy was undertaken 1 to 4 times in each patient (a total of 37 times in all patients). During endoscopy, random biopsies were taken from the pouch wall, and from the afferent and the efferent nipples. The histological changes were graded as: (1) villous atrophy (grade 0 to 3, 0: nearly normal; 1: shortening, villi/crypt of Lieberkuhn [length] between 1.5 and 4.0; 2: moderate flattening, villi/crypt < 1.5; and 3: almost complete disappearance of villi); (2) fibrosis; and (3) chronic inflammation (grade 0 to 3, based on the amount of fibrous tissue and inflammatory cell infiltration in the lamina propria, respectively). There was no dysplasia or malignant tumour in the Kock pouch in any of the 15 patients. The histology of the ileum changed in terms of villous atrophy, fibrosis and chronic inflammation in the lamina propria and thickening of the muscularis mucosa. The same grade of villous atrophy of the pouch wall, the afferent and the efferent nipples was only found in 3 patients. More fibrosis and less chronic inflammation in the lamina propria were found at the efferent nipple than at the afferent nipple or pouch wall in 8 patients and 5 patients, respectively. Thickening of the muscularis mucosa was found in 13 of 15 patients (86.7%). In conclusion, there was no dysplasia or recurrent tumour in the Kock pouch in patients who were followed for up to 66 months. Various grades of histological changes of the ileum in terms of villous atrophy, fibrosis and chronic inflammation of the lamina propria, and thickening of the muscularis mucosa were found in the pouch wall, and in the afferent and efferent nipples. More fibrosis and less chronic inflammation were commonly observed at the efferent nipple than at the afferent nipple or pouch wall. The degree of histological changes varied even among patients followed over the same period after operation. The time to progression of villous atrophy also varied. The histological changes in some patients were dissimilar even at the same site of the Kock pouch.

Aged↗
PubMed1993

Deoxyribonucleic acid histogram of testes in primary transsexualism.

The influence of oestrogen on spermatogenesis was evaluated by comparing its effect on the testes of primary male transsexuals and those who had undergone hormone therapy for prostatic carcinoma. Eight primary transsexuals were studied. They had been diagnosed on clinical and psychiatric evidence and had been on oestrogen therapy for several years since puberty. Histological sections of testicular tissue obtained at reassignment surgery from 8 phenotypic male transsexuals (aged 24-32 years) with an XY chromosome complement were studied by light microscopy. The formalin-embedded specimens were analysed by flow cytometry for deoxyribonucleic acid (DNA) histograms. Both the histology and DNA histograms revealed a pattern of maturation arrest in 12 of 16 testes in which the diploid cell compartment occupied most of the spermatogenetic element, followed by tetraploid and monoploid cells. Two testes showed impaired spermatogenesis and 2 were normal. The DNA histograms and pathology were also evaluated in 20 testes after 3 to 8 years of hormone therapy in patients with advanced prostatic carcinoma (aged 60-78 years). No maturation arrest was found in these patients. Sixteen of them had a pattern of fibrosis and atrophy and 4 had impaired spermatogenesis. It was concluded that oestrogen influenced spermatogenesis and affected the maturation of spermatogonia mostly during puberty.

Adult↗
PubMed1993

Long-term stone regrowth and recurrence rates after extracorporeal shock wave lithotripsy.

We reviewed 1055 patients with symptomatic urinary calculi treated by extracorporeal shock wave lithotripsy (ESWL) monotherapy to determine the long-term stone regrowth and recurrence rates as correlated with the pre-treatment stone burden, site and multiplicity. Long-term follow-up (mean 75.8 months) was available in 94 patients, representing 106 renal units. The recurrence of stone was defined as reappearance of stone on follow-up plain abdominal radiographs. The regrowth of stone was defined as stone regrowing larger than one-third of the original residual size. A stone-free rate of 53% was achieved. The overall stone regrowth and recurrence rates were 26 and 15% respectively. It was concluded that the stone recurrence rate after ESWL was not influenced significantly by the stone size or the multiplicity, but that the regrowth rate was. Stone recurrence and regrowth rates after ESWL were both influenced by the stone location.

Adult↗
PubMed1993

Experience using extracorporeal shock-wave lithotripsy to treat urinary calculi in problem kidneys.

Seventeen patients with urolithiasis in problem kidneys which comprised horseshoe kidneys, medullary sponge kidneys (MSKs), polycystic kidneys and duplex kidneys presented to our hospital and were evaluated for treatment with extracorporeal shock-wave lithotripsy (ESWL). A total of 21 renal units were treated with ESWL. Auxiliary procedures included preoperative retrograde ureteral catheterization (1 horseshoe kidney) placement of a retrograde double-J catheter stent (1 MSK), percutaneous nephrolithotomy (PCNL; 2 MSKs) and postoperative PCNL (1 MSK). The outcome showed that 5 renal units (23.8%) were stone free, 15 renal units (71.4%) had a decreased stone load with residual stone and improved symptoms, and 1 renal unit (4.8%) had residual stone with persistent symptoms. We conclude that ESWL can be used as a primary management tool for calculi in problem kidneys.

Female↗
PubMed1993

Local chemolysis of obstructive uric acid stone with 0.1 M THAM and 0.02% chlorhexidine.

We used a modified chemolytic solution by combining 0.1 M THAM (tris[hydroxymethyl] aminomethane) with 0.02% chlorhexidine to treat 10 obstructive uric acid stone patients. A total of 23 local chemolysis sessions were performed. Five patients received 13 sessions (average: 2.6) as an adjuvant chemolysis after extracorporeal shock wave lithotripsy 5 patients received 10 sessions (average: 2) as a primary treatment. The average time of local chemolysis was 2.3 days, ranging from 1 to 4 days. In the 23 local chemolysis sessions, only one patient developed two episodes of fever (8.7%), which were managed successfully by conservative treatment. The mean values of effective renal plasma flow of treated kidney was increased from 108.2 to 155.6 ml/min (p < 0.05). The stone-free rate assessed by IVP and ultrasonography at 3 months follow-up was 80%. Our results indicate that the combined use of 0.1 M THAM and 0.02% chlorhexidine is an effective and safe method to treat obstructive uric acid stones.

Aged↗
PubMed1993

Intradiverticular tumors of the bladder: surgical implications--an eleven-year review.

An 11-year review of all vesical diverticula and bladder tumors was undertaken. Fourteen patients were found to have primary neoplasms arising in the diverticula. The most common type was transitional cell. Hematuria was the most common presentation. Diagnosis is relatively difficult and treatment is not well defined. Lack or thinness of muscular layer of the diverticulum also potentiates early peridiverticular invasion and results in poor prognosis. Early diagnosis and adequate treatment are indicated.

Aged↗
PubMed1993

Acute pancreatitis following transurethral resection of prostate.

Three cases of acute pancreatitis following transurethral resection of the prostate are reported. The incidence is rare. A review of perioperative data failed to disclose any unique factor except in 1 patient who had an underlying biliary tract disease. Hyperamylasemia or hyperlipaemia in association with abdominal pain and vomiting was noted in all patients to establish the diagnosis. Computed tomography also confirmed the existence of acute pancreatitis. One patient died of respiratory and renal failure. However, early diagnosis and prompt treatment are essential to reduce high mortality. In conclusion, acute pancreatitis should be considered as one of the differential diagnoses in the presence of abdominal pain with vomiting, azotemia or oliguria after transurethral resection of the prostate.

Acute Disease↗
PubMed1993

Silica stone--development due to long time oral trisilicate intake.

We report a case of a 30-year-old female who had a long-term history of trisilicate-containing antacid intake for gastric discomfort. She had experienced repeated attacks of renal colic. Neither intravenous pyelography nor ureteroscopy could define the presence of calculi. The metabolic evaluations were normal. However, X-ray diffraction revealed a silicate stone. We suggest that the attack of renal colic in those patients with long-term history of trisilicate intake should arouse the possibility of silica urolithiasis.

Administration, Oral↗
PubMed1993

Experience in the morbidity associated with double-J catheter indwelling and its management.

Placement of internal ureteral stents for internal urinary diversion and prevention of urological complications has been well established. However, indwelling stents have occasionally been associated with patient morbidity and intolerance. A total of 255 patients while the internal ureteral stent had been used were analyzed. The symptoms including urinary frequency (42.0%), hematuria (41.6%) and suprapubic pain (20.4%), loin pain (17.3%) and micturition pain (16.9%) accounted for the major complaints of the stent indwelling patients. The major complications, i.e. stent migration, heavy encrustation, pyelonephritis, fragmentation, intolerance and penetration of collecting structure, were occasionally observed. These complications increase secondary morbidity in patients. The double-J stents should be used carefully with regard to the prevention and treatment of untoward conditions as early as possible.

Adolescent↗
PubMed1993

Reversed cephalic vein: a lifeboat in head and neck free-flap reconstruction.

Free flaps always followed surgical resection in head and neck cancer patients as a means of reconstruction. Problems may be encountered in recurrent patients who have received postoperative cervical irradiation, since finding a good, healthy vein for microanastomosis is sometimes difficult. The internal jugular vein, with or without vein grafting, as the recipient vessel may solve the problem. However, we encountered two patients in whom the internal jugular vein was very fibrotic as a result of irradiation. A long vein graft to the nonirradiated, healthy area was the only choice in this condition. A new method in which a reversed cephalic vein is used as the recipient vessel was designed. It seems that the reversed cephalic vein can play the role of lifeboat as recipient vein and solve the most difficult problem encountered in head and neck free-flap surgery.

Fibrosis↗
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↗