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Biomedical subjects

L S Chang

Publications and source records attributed to L S Chang.

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

Human erythrocyte protein 4.2: isoform expression, differential splicing, and chromosomal assignment.

Human protein 4.2 (P4.2) is a major membrane skeletal protein in erythrocytes. Individuals with P4.2 deficiency exhibit spherocytosis and experience various degrees of hemolytic anemia, suggesting a role for this protein in maintaining stability and integrity of the membrane. Molecular cloning of P4.2 cDNAs showed that P4.2 is a transglutaminaselike molecule in erythrocytes but lacks the essential cysteine for cross-linking activity. Two cDNA isoforms have been identified from a human reticulocyte cDNA library, with the long isoform containing a 90-base pair (bp) in-frame insertion encoding an extra 30 amino acids near the N-terminus. Characterization of the P4.2 gene suggests differential splicing as the mechanism for generating these two cDNA isoforms. The donor site for the short isoform (P4.2S) agrees better with the consensus than the donor site for the long isoform (P4.2L) does. Expression of P4.2L was detected by a long-isoform-specific antibody raised against a peptide within the 30-amino acid insert. Western blot analyses showed P4.2L to be a minor membrane skeletal protein in human erythrocytes with an apparent molecular weight (mol wt) of approximately 3 Kd larger than the major protein 4.2, P4.2S. By in situ hybridization of a full-length 2.4-kilobase (kb) cDNA to human metaphase chromosomes, the gene for P4.2 was mapped to bands q15-q21 of chromosome 15, and it is not linked to the gene for coagulation factor XIIIa (plasma transglutaminase, TGase).

Amino Acid Sequence↗
PubMed1992

Molecular cloning of the cDNA for the catalytic subunit of human DNA polymerase delta.

The cDNA of human DNA polymerase delta was cloned. The cDNA had a length of 3.5 kb and encoded a protein of 1107 amino acid residues with a calculated molecular mass of 124 kDa. Northern blot analysis showed that the cDNA hybridized to a mRNA of 3.4 kb. Monoclonal and polyclonal antibodies to the C-terminal 20 residues specifically immunoblotted the human pol delta catalytic polypeptide. A multiple sequence alignment was constructed. This showed that human pol delta is closely related to yeast pol delta and the herpes virus DNA polymerases. The levels of pol delta message were found to be induced concomitantly with DNA pol delta activity and DNA synthesis in serum restimulated proliferating IMR90 cultured cells. The human pol delta gene was localized to chromosome 19 by Southern blotting of EcoRI digested DNA from a panel of rodent/human cell hybrids.

Amino Acid Sequence↗
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

Immunochemical properties of Naja naja atra (Taiwan cobra) phospholipase A2 using polyclonal and monoclonal antibodies.

The immuno-chemical properties of Naja naja atra phospholipase A2 (NNA-PLA2) were studied by using the chemically modified PLA2 derivatives and the PLA2 homologues toward anti-NNA-PLA2 polyclonal and monoclonal antibodies. Anti-NNA-PLA2 polyclonal antibodies inhibited the enzymatic activity of NNA-PLA2 and Hemachatus haemachatus DE-I by 87% and 68%, respectively. However, the enzymatic activities of Naja nigricollis CMS-9 and notexin were not significantly affected by the polyclonal antibodies. Competitive enzyme immunoassay revealed that the affinity of NNA-PLA2 for polyclonal antibodies was 330-fold higher than that of Hemachatus haemachatus DE-I. Naja nigricollis CMS-9 and notexin failed to inhibit the binding of NNA-PLA2 to polyclonal antibodies. This implies that the epitope(s) of NNA-PLA2 might comprise some substituted residues in the sequence of PLA2 homologues. Three monoclonal antibodies against NNA-PLA2 were prepared by a hybridoma technique. Two of these monoclonal antibodies inhibited the enzymatic activity of NNA-PLA2, but the other did not. Removal of the N-terminal octapeptide affected the epitope interacting with these monoclonal antibodies. Selective modification of tyrosine residues at positions 3 and 63 or lysine residues at positions 6 and 65 induced a substantial reduction in affinity of NNA-PLA2 for polyclonal and monoclonal antibodies. The three monoclonal antibodies failed to recognize PLA2 homologues. The comparison of the sequence of NNA-PLA2 to those of PLA2 homologues showed that most of the amino acid substitutions of PLA2 homologues occur in the spatially nearby region of the N-terminal region and residues at positions 63 and 65.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
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

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

The filter properties of the arterial beds of organs in rats.

The frequency properties of arterial beds in organs were studied by temporarily ligating the renal, the gastric, the splenic or the superior mesenteric arteries of rats. Blood-pressure waves of the tail arteries were recorded before and during the ligations, and were analysed by Fourier's transformation. Their frequency spectra have been found to change profiles following specific patterns with the ligations of different arteries. The results were significant with regard to the frequency selectivities of the organic arterial beds. Such frequency properties can be clearly explained when the circulation system is viewed as an electrical circuit network in which the organic arterial beds work as filters.

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

A second observation of the fetal methemoglobin variant Hb F-M-Fort Ripley or alpha 2G gamma 2(92)(F8)His----Tyr.

We have identified a second baby with the fetal methemoglobin F-M-Fort Ripley. It was observed in a Caucasian infant from Canada; at least eleven additional members of that family were known to have had a neonatal cyanosis similar to that seen in the propositus and in a previously described baby (2). Sequencing of amplified DNA that included (part of) the G gamma gene greatly facilitated the characterization. The G gamma X chain was readily isolated by reversed phase high performance liquid chromatography; its quantity was approximately 12.5% of total gamma. Interestingly, the baby also carried the A gamma T mutation on one chromosome, either in cis or in trans to the G gamma X mutation. Hb F-M-Fort Ripley could be isolated in reasonably pure form by DEAE-cellulose chromatography. The isolated Hb FX was unstable, had spectral changes characteristic for the M-hemoglobins, while its methemoglobin derivative reacted rapidly with cyanide. Oxygen affinity data could not be obtained. It is suggested that the formation of a rather large amount (approximately 25%) of mixed hybrids (alpha 2G gamma X.gamma) with low oxygen affinity is the main cause for the occurrence of the neonatal cyanosis.

Base Sequence↗
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↗