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Biomedical subjects

T F Chen

Publications and source records attributed to T F Chen.

At least 37 records · Page 2Linked to original sources
PubMed1992

Inhibitory role of gamma-amino-butyric acid in the rabbit urinary bladder.

Gamma-amino-butyric acid (GABA) is an established inhibitory neurotransmitter in the central nervous system (CNS) and it has also been identified in the bladder. We have investigated in the rabbit the effect of GABA on detrusor activity. Rabbit detrusor muscle strips were made to contract by electrical stimulation of their autonomic nerves or by the addition of carbachol. The addition of GABA caused substantial inhibition of muscle contraction. GABA acts on 2 classes of receptors-GABAA and GABAB. The inhibition was mediated via the GABAB receptors as its effect was mimicked by baclofen (a GABAB agonist) and inhibited by 2-hydroxysaclofen (a GABAB receptor antagonist). Inhibition was not prevented by bicuculline (a GABAA receptor antagonist). This inhibition may be due to a direct muscle effect since the inhibition, which occurred with carbachol-induced contraction, was not abolished by the addition of tetrodotoxin. GABA, acting via the GABAB receptor, produces substantial inhibition of muscle contraction in the rabbit urinary bladder. This raises the possibility of using GABAB analogues in the treatment of detrusor instability.

Animals↗
PubMed1992

Rectal obstruction secondary to carcinoma of the prostate treated by transanal resection of the prostate.

Rectal obstruction caused by carcinoma of the prostate is uncommon. If the disease does not respond to either hormonal treatment or radiotherapy, the only surgical means of relieving the obstruction has been the formation of a colostomy. We present an alternative treatment, since many of these patients are elderly with a short life expectancy and they may have difficulty coping with a stoma. Seven transanal endoscopic resections of the prostate (TARP) have been performed on 5 patients. The procedure is not without complications, but it does offer simple surgical palliation of the rectal obstruction and obviates the need for a colostomy.

Aged↗
PubMed1991

Epididymectomy for post-vasectomy pain: histological review.

Fifteen epididymectomies were performed on 10 patients with post-vasectomy pain and 12 specimens were available for histopathological review. The findings were compared with those in 2 groups in which epididymectomy was performed for chronic epididymo-orchitis and epididymal cysts. The results showed that 50% of the post-vasectomy group were cured by simple epididymectomy. Pathological findings revealed features of long-standing obstruction and interstitial and perineural fibrosis which may have accounted for the pain. It is important to recognise this late complication of vasectomy and, if surgery is to be performed, to include all of the distal vas and previous vasectomy site in the excision.

Adult↗
PubMed1991

Intraperitoneal rupture of an infected urachal cyst in an infant. Case report.

Peritonitis due to intraperitoneal rupture of an infected urachal cyst is a life-threatening condition, not previously reported in an infant. We report this condition in an 8-month-old infant. The child underwent complete excision of the urachal remnant and made an uneventful recovery; bacterial culture grew Staphylococcus aureus. Subsequent investigations did not reveal any other renal tract abnormalities.

Humans↗
PubMed1990

Obstructing tracheal lipoma: management of a rare tumor.

Benign neoplasms of the trachea are rare. We describe a 46-year-old patient with a lipoma arising from the membranous trachea and causing severe respiratory obstruction. Investigation and management of this problem are discussed, and the literature is reviewed.

Airway Obstruction↗
PubMed1990

[Enhancement of absorption of tetramethylpyrazine by synthetic borneol].

Sprague-Dawley rats were given ig tetramethylpyrazine phosphate (TMP) 5 mg/kg with or without previous borneol 5 mg/kg. The plasma TMP concentrations were analysed by GC method, and the data were treated by NONLIN program. The Cmax were 931 and 562 ng/ml, respectively, (P less than 0.01); while the AUC were 68,849 and 37,174, respectively, (P less than 0.05). It is suggested that the borneol enhances the absorption of the TMP but not in elimination.

Absorption↗
PubMed1989

Endometriosis of the recto-vaginal septum treated by anterior resection.

Two young nulliparous females with severe symptomatic recto-vaginal endometriosis that had not responded to medical treatment were considered for surgery. Pre-operatively they were investigated by laparoscopy and Magnetic Resonance Imaging (M.R.I.) which demonstrated that the lesions were confined to the recto-vaginal septum with no intraperitoneal involvement. Both patients underwent resection of the middle third of the rectum and part of the posterior wall of the vagina with preservation of the ovaries, uterus and fallopian tubes. In one patient a J-colonic pouch with colo-anal anastomosis was fashioned and in the other patient a stapled colo-rectal anastomosis. Both patients are now asymptomatic with normal bowel function six months post-operatively. Radical surgery is indicated very rarely. We believe it should be considered in young nulliparous women who wish to conceive, in whom the diagnosis has been confirmed histologically and who have severe symptoms. M.R.I. is a useful pre-operative investigation to delineate the extent of the disease.

Adult↗
PubMed1989

[A case report and metallurgical analysis of broken Luque rod].

Wire breakage is frequently mentioned in Luque rod instrumentation with segmental sublaminar wiring, but breakage of the Luque rod is rare. A case report of a broken Luque rod in a patient following a scoliosis post-corrective operation is presented and a metallurgical analysis is provided to evaluate the mechanism of breakage. In the metallurgical analysis, we find many slots and dimples on the rod surface which were induced by an inappropriate bending apparatus and bending manipulation. These defects resulted in a stress concentration effect and initiated fatigue. As for the stress on the rod, this resulted from the force correcting the scoliotic deformity plus the load resulting from patient's daily activity, which increased the progression of fatigue and then induced the final breakage. So, to avoid Luque rod breakage we suggest that the bending manipulation be done appropriately, with external orthosis given to those patients with severe deformity or who are daily very active.

Adult↗
PubMed1988

Mass spectrometry of L-beta-aspartamido carbohydrates isolated from ovalbumin.

Using ovalbumin as a starting material, we have isolated and purified relatively large stocks of known glycopeptides for use as models with which to investigate and develop mass spectrometric procedures for the analysis of this class of compounds. In the process, we have discovered six new components in the L-beta-aspartamido carbohydrate fraction of ovalbumin. Positive and negative fast atom bombardment mass spectra, produced on a KRATOS MS50-TC, confirm that the newly found chromatographic peaks correspond to as yet unidentified compounds in the molecular weight range of 1000-3000. Fragment ion peaks present in the mass spectra of some of the unknown compounds can be rationalized in terms of the fragment ion patterns established from the structures of the known glycoasparagines.

Animals↗
PubMed1973

N,O-di and N,N,O-tri ( 3 H) acetyl -bungarotoxins as specific labelling agents of cholinergic receptors.

1. alpha-Bungarotoxin isolated from the venom of Bungarus multicinctus was acetylated with [(3)H] acetic anhydride and N-[(3)H] acetyl imidazole. Tri-N-acetyl and hexa-N-acetyl derivatives were obtained from the former, and N,O-di, N,N,O-tri and N,N,N,O-tetraacetyl derivatives from the latter reaction, respectively.2. There were parallel decreases in both neuromuscular blocking action in the phrenic nerve-diaphragm preparation of rats and depression of acetylcholine response of the rectus abdominis muscle of frogs with increased acetylation. Also, a parallel but greater decrease of toxicity in mice was found.3. N,O-Di and N,N,O-triacetyl toxins were localized mostly in the motor endplate region of the rat diaphragm, whereas a slight nonspecific binding along the whole muscle fibre in addition to the peak in the endplate region was observed with N,N,N,O-tetraacetyl and tri-N-acetyl toxins. In contrast, there was a marked nonspecific binding with hexa-N-acetyl toxin and no peak was observed at the endplate zone.4. The specific binding was saturable and irreversible. The number of toxin-receptive sites in one endplate was 1.9-2.2 x 10(7) for all of the labelled toxins irrespective of their potency.5. (+)-Tubocurarine protected effectively against the binding as well as the irreversible neuromuscular blocking effect of the toxins.6. Denervation of the rat diaphragm caused an increase of toxin-receptive sites beginning from the endplate zone at 1-2 days and then along the whole muscle fibre, reaching the maximum at about 18 days. The total receptive sites increased by about 30-fold.7. The significance of the findings is discussed and it is concluded that N,O-di and N,N,O-tri-[(3)H] acetyl alpha-bungarotoxins are specific and irreversible labelling agents for the cholinergic receptors of skeletal muscle.

Acetylation↗
PubMed1973

Influence of chronic neostigmine treatment on the number of acetylcholine receptors and the release of acetylcholine from the rat diaphragm.

1. Rats were treated twice daily for 7 days with neostigmine and the diaphragm was isolated for study of its acetylcholine content, release upon nerve stimulation and the number of receptors in the end-plate.2. While the content of total acetylcholine was unchanged, the release of acetylcholine on stimulation with trains of 500 pulses at 100 Hz every 20 sec was reduced by about 50%. Five days after the end of neostigmine treatment the release of acetylcholine recovered to normal.3. The total number of acetylcholine receptors in the end-plate as measured from the binding of N, O-di[(3)H]acetyl alpha-bungarotoxin was reduced from 2.1 x 10(7) to 1.2 x 10(7) per end-plate.4. The above-mentioned changes are not due to acute pharmacological effects of neostigmine, nor to an immediate effect of cholinesterase inhibition but presumably due to chronic accumulation of acetylcholine at the neuromuscular junction.

Acetylcholine↗