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Biomedical subjects

K K Chen

Publications and source records attributed to K K Chen.

At least 91 records · Page 5Linked to original sources
PubMed1990

Isolation and characterization of the gene encoding a novel, thermostable serine proteinase from the mould Tritirachium album Limber.

A number of proteinases are induced and secreted into the culture medium of Tritirachium album Limber when the nitrogen source is limited to exogenous proteins. We have constructed a cDNA library using the polyadenylated RNA isolated during the nutritional induction with bovine serum albumin. A full-length clone of a gene for a new proteinase (named proteinase R) was identified from this library. This clone contained sequences coding for the 108-amino-acid prepro-leader as well as for the 279-amino-acid mature proteinase. Proteinase R apparently belongs to the subtilisin group of serine proteases that contains disulphide bonds. Homology between proteinase R and proteinase K was found to be about 87% at the nucleotide as well as at the amino acid level. The Brookhaven Protein Data Base co-ordinate file of proteinase K was used as a template to study the proteinase R substitutions in three-dimensional space. The majority of the substitutions of proteinase R with respect to proteinase K were found to be on the exterior of the protein model.

Amino Acid Sequence↗
PubMed1990

Prophylactic bladder neck incision in the treatment of small benign prostatic hyperplasia.

From May 1986 to January 1989, a total of 178 patients with small prostate (less than 20 grams) received transurethral resection for benign prostatic hyperplasia. Twenty-two patients (12.4%) developed bladder neck contracture with an average interval of 247 days. The prophylactic bladder neck incision was performed concomitantly with transurethral resection of the prostate on 72 patients. Although smaller adenoma (average weight: 11.4 grams) was resected in this group, the bladder neck contracture occurred in 4 patients (5.6%), compared to 18 contractures in 106 patients (16.9%) who underwent transurethral resection of the prostate alone for larger adenoma (14 grams), P value less than 0.05. The operation time, peri-operative morbidity and hospital stay were similar in these two groups. It appeared that prophylactic bladder neck incision could protect against the formation of bladder neck contracture in patients with small obstructing prostatic adenoma.

Chi-Square Distribution↗
PubMed1990

Pyeloduodenal fistula: report of 2 cases.

Pyeloduodenal fistula is a rare event, which can occur spontaneously or be caused by trauma. We present two such cases, of which, one was complicated by percutaneous nephrolithotomy for a right renal stone and the other occurred spontaneously from right renal and perirenal abscesses. Its etiology, pathogenesis, clinical manifestations, diagnosis and treatment are discussed. We emphasize that with the increasing use of interventional uroradiologic procedures, particularly percutaneous nephrolithotomy, we may encounter more traumatic pyeloduodenal fistulae.

Abscess↗
PubMed1990

Retroperitoneal abscesses.

Abscesses developing within the retroperitoneal spaces are complicated serious surgical infections marked by an insidious, occult process lead to considerable mortality and morbidity. In a retrospective review of 39 retroperitoneal abscesses in our hospital. Attention is directed to clinical presentation, diagnosis and treatment. On average, 19.2 days was required to establish the diagnosis and overall mortality is 7.7%. Two patients suffered from complications of discharged sinus and recurrent abscess respectively. Computed tomography (CT) is thought to be the best diagnostic modality of retroperitoneal abscesses. Only 2 patients (5.3%) shows bilateral lesions. Detailed anatomic reviews detailing the pathogenesis of bilateral retroperitoneal abscess are also discussed.

Abscess↗
PubMed1989

Cloning and expression of the gene encoding a novel proteinase from Tritirachium album limber.

We have isolated the genomic and cDNA clones encoding a novel proteinase from the fungus Tritirachium album Limber, named proteinase T, synthesis of which is induced in skim milk medium. The coding sequence for this enzyme is interrupted by two introns in the fungal genome. The amino acid sequence of proteinase T as deduced from the nucleotide sequence is about 53% identical to that of proteinase K. Four cysteines are present in the mature proteinase, probably in the form of two disulfide bonds, which might explain the thermal stability of the proteinase. We have expressed the proT cDNA in Escherichia coli. The authenticity of the product has been characterized by Western blotting and N-terminal analysis of the recombinant product.

Amino Acid Sequence↗
PubMed1989

Urodynamic and clinical outcome of Kock pouch continent urinary diversion.

Urodynamic studies of the Kock pouch were conducted in 20 patients 3 to 36 months after radical cystectomy and urinary diversion for invasive bladder cancer. Functional pouch capacity, intrapouch pressure, maximal nipple pressure, maximal nipple closure pressure and functional nipple length with the pouch filled to capacity were measured. Intermittent involuntary pressure spikes resembling bowel peristaltic waves occurred in 5 patients (25 per cent). The mean functional pouch capacity was 280.0 +/- 119.2 ml. (standard deviation) and mean maximal intra-pouch pressure was 41.0 +/- 11.0 cm. water in patients with involuntary pressure spikes. In patients without involuntary pressure spikes these values were 332.7 +/- 114.5 ml. and 11.6 +/- 4.8 cm. water, respectively. For all patients the mean maximal nipple pressure was 72.1 +/- 24.6 cm. water, the mean maximal nipple closure pressure was 58.8 +/- 23.1 cm. water and the mean functional nipple length was 3.4 +/- 0.9 cm. A functional nipple length of less than or equal to 2.5 cm. and/or a low maximal nipple closure pressure (less than 40 cm. water) correlated with a small functional pouch capacity (less than 200 ml.) in 5 patients. Clinically, these 5 patients also required frequent catheterization to provide continence. A maximal nipple closure pressure greater than 60 cm. water and an adequate functional nipple length (greater than 3.0 cm.) correlated with a rather large functional pouch capacity (more than 350 ml.). The degree of continence provided by the Kock pouch appeared to be determined by functional nipple length, maximal nipple closure pressure, functional pouch capacity and maximal intrapouch pressure.

Aged↗
PubMed1989

Sarcomas of the retroperitoneum and genitourinary tract.

A total of 62 patients with retroperitoneal or genitourinary sarcoma was treated at our institutions during the last 46 years. Of the patients 51 were followed for at least 5 years or until they died (median followup 11 years); 5 patients were lost to followup. The most common site was the retroperitoneum. Liposarcoma, leiomyosarcoma and malignant fibrous histiocytoma were the most common tumors (74 per cent). Tumors were completely resected in 42 patients (68 per cent) and incompletely resected in 11, while a biopsy only was performed in 9. Some patients also received adjuvant radiation therapy and/or chemotherapy. There were no long-term survivors among patients with unresectable tumors. Over-all 3 and 5-year survival rates were 68 and 39 per cent, respectively. The histological type of the tumor appeared to have prognostic significance. The highest 5-year survivals were for liposarcoma (70 per cent), malignant fibrous histiocytoma (33 per cent) and leiomyosarcoma (13 per cent). The mean survival for patients after adjuvant radiation therapy or chemotherapy was similar to that after a radical operation alone. The primary cause of treatment failure was local recurrence (45 per cent of the patients), which was detected within 3 years of complete resection in most cases (82 per cent). Complete extirpation that provided adequate margins free of tumor was the most effective initial treatment and provided the best chance for cure.

Combined Modality Therapy↗
PubMed1989

Electrohydraulic lithotripsy for stones in Kock pouch.

During endoscopy of the Kock pouch, we found rather large stones in the pouches of 3 male patients 14-23 months after operation. The size of the stones varied from 1.5 to 3.5 cm. Because the stones in the pouch were too large to be extracted using forceps, for fear of damaging the efferent nipple valve, electrohydraulic lithotripsy (EHL) was applied and all stones could be broken down and removed easily. No complication occurred during or after EHL. Topical anesthesia was not necessary in all 3 patients. Usually the stones formed around staples. The major component of the stones was struvite. Urease-secreting bacteria as well as alkaline urine were found in all 3 patients. This result suggested that though EHL was used in an intestinal milieu (instead of urothelial bladder), it was an easy, safe and effective procedure for the removal of rather large stones (greater than 1.5 cm) from the Kock pouch. We suggest endoscopy of the Kock pouch at least once every 6 months or when stones have been demonstrated on plain X-ray of the abdomen. Stones in the pouch larger than 1.5 cm could be removed using EHL to avoid damaging the efferent nipple valve.

Humans↗
PubMed1989

[Experience in using modified HM-3 Dornier lithotripter to treat urinary tract stones].

Low pressure generator has been developed mainly to reduce pain and kidney injury while at the same time maintain an equally effective stone-free rate. Our experience in using Modified HM-3 Dornier lithotripter to treat urinary tract stones has given an average of stone-free rate (58.88%) quite similar to what the conventional one can give. Compared with the conventional intervention, the modified one might increase by 52.07% (2281 vs 1500 pulses) in the average frequency of shock wave and by 26.52% (38.40 vs 30.35 minutes) in average operation time. However, low pressure may contribute to less complications and overall smoother procedure under oral analgesic use.

Adolescent↗
PubMed1989

[Use of double-J in extracorporeal shock wave lithotripsy of large renal calculi].

Treatment of large renal calculi by extracorporeal shock wave lithotripsy alone has not been accepted yet as the treatment of choice because of the high incidence of complications such as stone street inducing obstructive uropathy. From Sep. 1987 to Nov. 1987, Thirty four patients had received double-J catheter in ureter before E.S.W.L. to prevent ureteral obstruction. The age distribution was from 29 to 66 years old (mean = 49.1 Y/O) and male to female ratio was 3:1. All the stone size was larger than 20mm in its longest axial length. Each patient was followed at least 3 months, and the results indicated that 8 patients (23.53%) had stone free, 11 patients (32.35%) had sandy stone in kidney, and 15 patients (44.12%) had stone street in ureter. The additional treatments for significant residual stone included 3 patients needing ureteroscopy, 8 patients needing more than one session of E.S.W.L. and 4 patients having spontaneous stone passage after removal of double-J. Although the necessity of external diversion and the incidence of colic pain after E.S.W.L. would reduce so as to improve patients' quality of life, double-J does not increase the stone free rate, and ureteral obstruction was still possible to induce the renal function impairment. We suggest that double-J be removed as soon as possible if the stone fragments have no change in position after 2-4 weeks of followup and adjuvant treatment be necessary.

Adult↗
PubMed1988

Patient acceptance of and satisfaction with vasoactive intracavernous pharmacotherapy for impotence.

Patient acceptance of and satisfaction with a trial of vasoactive intracavernous pharmacotherapy for impotence among 372 men were retrospectively analyzed. Drop out from the dosage determination phase and the training for injection phase was similar, 9.7 and 8.4 per cent, respectively, while 31.4 per cent of the patients dropped out of the home injection phase. Tachyphylaxis, inconvenience of the procedure or the frequent followup visits required, side effects and concern about unknown long-term effects were the main reasons patients cited for dropping out of the trial. The degree of satisfaction among patients who entered the home injection phase was high. Only 55 patients who dropped out of the trial chose implantation of a penile prosthesis. Vasoactive intracavernous pharmacotherapy is an effective treatment for impotence of various etiologies, and in a carefully selected group of patients the acceptance of and satisfaction with this therapy are high.

Clinical Trials as Topic↗
PubMed1988

Ocular hypotensive efficacy of 0.25% levobunolol instilled once daily.

The authors evaluated the efficacy of once-daily treatment with levobunolol in patients with primary open-angle glaucoma or ocular hypertension in an open-labeled, two-phase titration clinical trial. All patients started the study using 0.25% levobunolol administered once daily for 3 months (phase I). If a patient's intraocular pressure (IOP) was not controlled with this concentration of levobunolol, the concentration was increased to 0.5% administered once daily for 3 months (phase II). During phase I, a significant reduction in IOP was observed in 21 of the 29 patients (72%), with an average IOP reduction of 24%. During phase II, in six patients whose IOP was reduced inadequately with 0.25% levobunolol, one had a significant reduction in IOP with 0.5% levobunolol. The authors concluded that levobunolol, instilled once daily at a concentration of 0.25%, was effective in significantly reducing IOP in the majority of the patients evaluated.

Adult↗
PubMed1988

Identification of a region in the S1 subunit of pertussis toxin that is required for enzymatic activity and that contributes to the formation of a neutralizing antigenic determinant.

The S1 subunit of pertussis toxin possesses two regions (homology boxes), each spanning 8 residues, that are nearly identical in sequence to similarly located regions in the enzymatically active A fragments of two other ADP-ribosylating toxins: cholera toxin and Escherichia coli heat-labile toxin. This observation suggests a functional role for one or both of these regions in enzymatic activity. We have examined the role of one of these regions, located near the amino terminus of the S1 subunit, by using a high-level recombinant expression system and progressive truncation of the gene sequence encoding the amino terminus of the molecule. A series of six truncated, recombinant proteins were produced at high levels in E. coli and examined for their enzymatic and antigenic properties. The three molecules that lacked most or all of the homology box delimited by amino acid residues 8 and 15 lacked detectable enzymatic activity. All of the three molecules in which the box was retained exhibited detectable activity. Only those recombinant molecules that possessed the homology box reacted with a neutralizing and passively protective monoclonal anti-S1 antibody. These findings identify the region of homology located near the amino terminus of S1 as an apparent enzymatic subsite and a potentially important antigenic determinant.

Adenosine Diphosphate Ribose↗