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Biomedical subjects

R Park

Publications and source records attributed to R Park.

At least 55 records · Page 3Linked to original sources
PubMed1994

Mortality at an automotive stamping and assembly complex.

Mortality among workers with 2 or more years employment at an automotive stamping and assembly complex was analyzed using standardized mortality ratio (SMR), proportional mortality ratio (PMR), and mortality odds ratio (MOR) methods. The stamping plant all-cause SMR was considerably less than expected (for white men, SMR = 0.65, 95% confidence interval [CI] = 0.54, 0.79; for black men, SMR = 0.73, 95% CI = 0.45, 1.13), indicating a strong "healthy worker effect." However, six stomach cancer deaths produced an SMR of 4.4 (95% CI = 1.62, 9.6) and a PMR of 6.8 (95% CI = 2.5, 15). Based on small numbers of cases, stomach cancer risk increased with duration in stamping and tool and die departments where exposures included drawing compound and other metalworking fluids. Stamping plant lung cancer mortality was elevated among production welders (MOR = 2.7, 95% CI = 1.2, 6.3), and increased with duration. Welding was performed on sheet metal sometimes coated with drawing compound, primer, or epoxy resin adhesive. As was observed for the stamping plant, the all-cause SMR for the two assembly plants was unusually low (for white men, SMR = 0.64, 95% CI = 0.56, 0.73; for black men, SMR = 0.57, 95% CI = 0.43, 0.75). The lung cancer SMR was not elevated but the MOR was (MOR = 1.58, 95% CI = 1.1, 2.4) and increased with assembly plant duration (MOR = 1.78, 95% CI = 1.02, 3.1, at mean duration of cases). In the assembly plants, paint oven stack emissions had been reintroduced into the plant by the ventilation system.

Black or African American↗
PubMed1994

Clinical stage IB endometrial adenocarcinoma with an isolated small bowel metastasis.

Although patients with widely disseminated endometrial adenocarcinoma can have tumor involving the intestine, a focal metastasis to the small bowel with no other evidence of extra-uterine spread has not been reported. A patient with a clinical stage IB, grade 2 superficially invasive endometrial adenocarcinoma was found to have an isolated distant metastasis to the small intestine. The patient has been asymptomatic and disease free for almost 4 years following postoperative treatment with whole abdominal radiation therapy on a Gynecologic Oncology Group protocol. The finding of a solitary small bowel metastasis was not predictable based on the current understanding of the biologic behavior of endometrial adenocarcinomas. This case emphasizes the need for a thorough abdominal exploration in patients with endometrial adenocarcinoma by surgeons trained to detect and resect abdominopelvic tumors, and it validates the need for innovative treatment protocols for women with gynecologic malignancies.

Anastomosis, Surgical↗
PubMed1994

Excitatory and inhibitory effects of serotonin on spinal axons.

We studied the effects of serotonin on compound action potentials in dorsal columns isolated from young (nine to 13 days old) rats. Conducting action potentials were activated by submaximal (50%) and supramaximal constant current electrical stimuli and recorded with glass micropipettes. At 10 microM and 100 microM concentrations, serotonin significantly increased mean action potential amplitudes by 9.6 +/- 6.5% (+/- S.D., P < 0.05) and 16.6 +/- 12.2% (+/- S.D., P < 0.005), respectively. Likewise, 10 microM and 100 microM of quipazine (a serotonin2A agonist) increased the amplitudes by 9.6 +/- 2.5% (+/- S.D., P < 0.0005) and 37.7 +/- 8.7% (+/- S.D., P < 0.0005), respectively. In contrast, 10 microM and 100 microM concentrations of 8-hydroxy-dipropylaminotetralin-hydrobromide (a serotonin 1A agonist) reduced axonal excitability by -9.4 +/- 5.5% (+/- S.D., P < 0.05) and -32.9 +/- 10.6% (+/- S.D., P < 0.0005), respectively. At 50 microM concentration, mianserin (a serotonin2A and serotonin2C antagonist) eliminated the excitatory effects of 100 microM quipazine dimaleate. The combination of 50 microM mianserin and 100 microM serotonin reduced action potential amplitudes by -5.6 +/- 4.9% (+/- S.D., P < 0.05). These results suggest that serotonin1A and serotonin2A receptor subtypes are present on spinal dorsal column axons. These two receptor subtypes have opposing effects on axonal excitability. The ratios and sensitivities of these two axonal receptor subtypes may modulate axonal excitability in rat dorsal column axons and have important implications for both development and injury of axons.

8-Hydroxy-2-(di-n-propylamino)tetralin↗
PubMed1993

Management of advanced ovarian epithelial cancer in the renal transplant patient.

Stage IIIC, grade 1 papillary serous adenocarcinoma of the ovary was diagnosed in a 28-year-old renal transplant recipient. She had been treated with the immunosuppressive agents azathioprine and methylprednisolone for 7 years prior to the discovery of the ovarian cancer. Surgical excision of the tumor was suboptimal due to involvement of the allograft; however, the patient achieved a complete clinical response after eight courses of cisplatin and cyclophosphamide. Since multiagent immunosuppressant therapy may have contributed to the development of the ovarian carcinoma, the intensity of immunosuppression was decreased by discontinuing the azathioprine as soon as the diagnosis of ovarian cancer was made. The methylprednisolone, however, was continued to decrease the possibility of organ rejection. After completion of chemotherapy, the patient was started on a daily regimen of low-dose oral cyclophosphamide as an immunosuppressant. Four months following the completion of cytotoxic therapy, she developed clinically evident disease in the pelvis. Subsequent salvage therapy with carboplatin failed. The patient died from progressive disease 26 months after initial diagnosis. She never developed evidence of renal rejection. Combined modality cancer therapy, preservation of allograft function, and modification of immunosuppressant therapy are important goals in the renal transplant patient with advanced ovarian carcinoma.

Adult↗
PubMed1993

Etiology of the sexual dimorphism in renal peripheral benzodiazepine receptor response to stress in rats.

A sexual dimorphism in stress-induced alterations in renal peripheral benzodiazepine receptors (PBR) was recently reported. The present paper includes five experiments examining the etiology of this sex difference. Surgical removal of ovaries and testes was ineffective in altering the renal PBR stress response in both male and female rats. A diurnal variation in the sexual dimorphism was observed; the difference was seen in the early part of the light cycle, while the two sexes were indistinguishable at the end of the light cycle. Finally, based on recent data indicating the importance of the renin-angiotensin system in the stress-induced decrease in renal PBR, we examined both stress-induced plasma renin activity and renal PBR reactivity to exogenous angiotensin II (AII) administration in both sexes. Female rats show both an attenuated elevation of plasma renin levels in response to inescapable shock stress and a reduced PBR response to AII administration in comparison to males. The present data indicate that the renin-angiotensin system may be a critical factor in the sexual dimorphism in the renal PBR response to stress. The possibility of this difference in the renin-angiotensin system contributing to sex differences in susceptibility to escape deficits following inescapable shock is entertained. The implications for these findings regarding the physiological function of the PBR are also discussed.

Angiotensin I↗
PubMed1993

Ovarian management during radical hysterectomy in the premenopausal patient.

OBJECTIVE: To determine whether the ovaries should be retained or removed in premenopausal women undergoing radical hysterectomies for cervical carcinoma. METHODS: Questionnaires were sent to all women who had radical hysterectomies without further therapy for cervical carcinoma at our institution over a 16-year period. Those who had retained ovarian tissue were asked to have serum gonadotropin levels measured. RESULTS: Eighty-four of 124 eligible women (68%) responded. Sixty-eight respondents were premenopausal at the time of surgery. Thirty-eight had a bilateral salpingo-oophorectomy (BSO), 20 had one ovary preserved, and ten retained both ovaries. Six of 30 (20%) who retained ovaries developed early hormonal failure. Two of these 30 (7%) required oophorectomies subsequently. Twenty-seven of 38 BSO patients (71%) were compliant with their hormone replacement regimens. Fourteen of 15 women (93%) age 40 or younger were compliant, whereas 13 of 23 (57%) over age 40 were compliant (P < .05). Twenty-three of 34 BSO respondents (68%) reported improved or unchanged sexual relations, compared with 24 of 27 (89%) who retained ovaries (P > .05). CONCLUSIONS: Twenty-seven percent of our premenopausal women with retained ovaries have experienced early loss of hormonal function or required subsequent oophorectomies. For an accurate estimate of ovarian longevity, all patients would have to be followed through menopause. Compliance in taking hormone medication was high in our young patients. Sexual function was not adversely affected following castration. A hypothetical cost comparison favored removing, rather than retaining, the ovaries. We recommend that elective BSO be performed on most premenopausal women undergoing radical hysterectomies for cervical carcinoma.

Adult↗
PubMed1992

Clinical surveillance of gynecologic cancer patients.

A survey of gynecologic oncologists was used to determine the optimum follow-up plan for asymptomatic, disease-free patients previously treated for a gynecologic malignancy. Ninety-four (91%) of 103 questionnaires were completed and returned. The majority of respondents recommended a clinic visit for these patients every 3 months for the first year after the completion of therapy, every 3 or 4 months for the second year, every 6 months for the following 3 years, and then annually after this initial 5-year period. Breast, abdominal, lymph node, and pelvic examinations, as well as a pap smear and stool guaiac, were done at each of these clinic visits. A yearly chest X ray was performed by the majority of the survey respondents for the first 3 years following initial treatment. Determinations of serum CA-125 and ovarian germ cell tumor markers were done at each follow-up appointment during the first 5 years after therapy if they were previously elevated. The patients' smoking habits were discussed with them by the majority of respondents. Mammograms were performed periodically before age 50 and then yearly after age 50 by most respondents. Serum cholesterol determinations were accomplished every 5 years or more frequently if indicated. Calcium supplementation was recommended for postmenopausal patients. The majority of respondents did not recommend routine vitamin supplementation or surveillance sigmoidoscopy.

Ambulatory Care↗
PubMed1992

Stress resistance of Drosophila transgenic for bovine CuZn superoxide dismutase.

Several oxidative and non-oxidative stresses were applied to two transgenic strains of Drosophila melanogaster (designated P(bSOD)5 and P(bSOD)11) that express superoxide dismutase (SOD) at elevated levels, and control strains that express normal SOD levels. Transgenic strain P(bSOD)5 exposed to paraquat (1,1'-dimethyl-4,4'-bipyridinium dichloride), a redox cycling agent that generates superoxide anion when metabolized in vivo, was significantly more resistant to this xenobiotic than control flies. When test flies were subjected to 100% oxygen for 20 min each day, the mean lifespan was 3.62 days for control strain 25, but 4.35 days for both transgenic strains. The mortality curves of strains fed 1% H2O2 were similar, but the median lifespan of 72 h for controls and 64 h for transgenics suggests that the transgenic flies were slightly more sensitive to H2O2. The activity of catalase was the same for all strains. Using starvation resistance as a non-oxidative stress, flies maintained on water without any food had identical survival curves; for all strains, the median lifespan was 72 h. Throughout the lifespan, no statistically significant difference in physical activity was displayed for transgenic versus control flies. Collectively, these data suggest that the increased lifespan previously observed in SOD transgenics is specifically related to resistance to oxidative stresses.

Animals↗
PubMed1992

Intestinal invasion by a dysgerminoma in a patient with Swyer syndrome.

An unusual case is presented of advanced dysgerminoma in a patient with Swyer syndrome, 46,XY pure gonadal dysgenesis. Unexpected regional invasion necessitated bowel resection, total abdominal hysterectomy, and bilateral salpingogonadectomy for a complete en bloc excision of the primary tumor mass and the dysgenetic gonads. This report illustrates the possible need for extensive operative resection in patients with Swyer syndrome.

Adnexa Uteri↗
PubMed1991

Nongenital pelvic leiomyosarcoma metastatic to the heart.

A patient who had a 5-year history of a low-grade nongenital pelvic leiomyosarcoma was evaluated for worsening dyspnea, hypertension, and jugular venous distension. An echocardiogram revealed a large right atrial mass. At surgical exploration, metastatic leiomyosarcoma was found within the inferior vena cava extending from below the renal veins up into the right atrium. Using cardiopulmonary bypass with profound hypothermia and circulatory arrest, the inferior vena cava was opened below the renal veins, and the tumor was transected. That portion of the tumor above this transection was then extracted through a right atriotomy. Resection of the pelvic tumor was not thought to be feasible. The patient remains asymptomatic with stable pelvic tumor 1 year after the procedure.

Female↗
PubMed1991

Intestinal surgery performed on gynecologic cancer patients.

A retrospective review covering a 9-year period revealed 113 patients who underwent 157 major bowel procedures during 130 operations performed solely by gynecologic oncology surgeons. Forty-eight percent of the operations were done for tumor cytoreduction, and 33% were performed for a bowel obstruction. Other indications included colostomy closure, fistula repair, resection for multiple enterotomies, temporary diversions, repair of perforated bowel, treatment for severe proctosigmoiditis, management of ureteral stricture, treatment for vulvar necrosis, and resection of an incidental small bowel tumor. Of the 157 procedures, 44% were colostomies, 32% were bowel resections with reanastomosis, 9% were urinary conduits, 6% were intestinal bypass procedures, 5% were colostomy closures, and 4% were ileostomies. Postoperative complications occurred in 32% of the 130 operations. These included wound infection, death, sepsis, fistula formation, urinary tract infection, unexplained febrile morbidity, anastomotic leakage, stomal infarction, adult respiratory distress syndrome, bowel obstruction, deep venous thrombosis, and wound hematoma. Four of the eight deaths were due to tumor progression, three were from sepsis, and one was from adult respiratory distress syndrome. Of the 130 operations, 89 (68%) were associated with no complications. These data support the concept that gynecologic oncology surgeons are able to perform intestinal operations as therapy for gynecologic malignancies with acceptable complication rates. Since a thorough understanding of the natural history of the cancer, familiarity with alternative therapeutic options, and knowledge of the prognosis are important in making operative decisions, and since gynecologic oncologists are technically capable of performing operations on the small bowel and colon, referral of patients with a primary or recurrent gynecologic malignancy or with a subsequent intestinal complication after initial therapy should be directed to the gynecologic oncologist whenever possible.

Adult↗
PubMed1991

A technique for managing terminally ill ovarian carcinoma patients.

A patient with terminal ovarian carcinoma was admitted with malnutrition, abdominopelvic pain, and an inoperable complete small bowel obstruction after failing standard therapy and several experimental regimens for her disease. Despite this serious situation, she had an overall high performance status. Instead of administering intravenous narcotics, providing nasogastric suction, and giving other supportive care to make her apparently imminent death as comfortable as possible, her malnutrition was treated with total parenteral nutrition administered through an indwelling central venous catheter during the night hours only. The pain was successfully treated with an indwelling epidural catheter with the continuous infusion of morphine through a portable pump carried by a shoulder strap. The intestinal obstruction was relieved by a percutaneous endogastric tube which drained spontaneously into a leg bag. This regimen allowed the patient complete daytime mobility. She remained active, largely at home, with slowly progressing tumor until her death 9 months after the institution of this supportive care.

Adult↗
PubMed1991

Radical vulvectomy with partial rectal resection and temporary colostomy as primary therapy for selected patients with vulvar carcinoma.

The patient with carcinoma of the vulva may present with tumor involvement of the perirectal area. Traditional treatment has often involved ultraradical therapy including a radical vulvectomy with posterior or total pelvic exenteration in an effort to obtain adequate surgical margins. Five-year survival rates for these patients range from 20-50%, and major operative morbidity as well as psychological problems are associated with this extensive surgery. Five patients treated for a locally advanced vulvar carcinoma involving the perirectal area were thought to be candidates for a rectum-sparing procedure. They underwent a radical vulvectomy, bilateral inguinal lymphadenectomy, partial rectal resection, and a diverting colostomy. Four of the five patients agreed to a colostomy closure 6 months after their primary therapy; these four patients have resumed normal bowel function. All patients remain clinically free of tumor.

Adenocarcinoma↗
PubMed1991

Indwelling epidural catheters for pain control in gynecologic cancer patients.

Seven patients with severe pain caused by an advanced, incurable gynecologic malignancy were treated with an indwelling epidural catheter connected to an implantable subcutaneous port through which morphine was infused. There were few major complications associated with insertion or maintenance of the system. The average usage was 60 days, although the system functioned continuously for 6 months in one patient. Pain distribution in these women ranged from the upper abdomen to the lower extremities. All patients, including one with liver metastases, reported good to excellent pain control with the epidural narcotics. Two subjects with upper abdominal pain occasionally required supplemental oral oxycodone, but the other five patients had adequate pain relief with the epidural system alone. The indwelling epidural system provides excellent analgesia for patients with advanced, incurable gynecologic cancer.

Adult↗
PubMed1990

Adjuvant therapy in stage I and stage II epithelial ovarian cancer. Results of two prospective randomized trials.

About a third of patients with ovarian cancer present with localized disease; despite surgical resection, up to half the tumors recur. Since it has not been established whether adjuvant treatment can benefit such patients, we conducted two prospective, randomized national cooperative trials of adjuvant therapy in patients with localized ovarian carcinoma (International Federation of Gynecology and Obstetrics Stages Ia to IIc). All patients underwent surgical resection plus comprehensive staging and, 18 months later, surgical re-exploration. In the first trial, 81 patients with well-differentiated or moderately well differentiated cancers confined to the ovaries (Stages Iai and Ibi) were assigned to receive either no chemotherapy or melphalan (0.2 mg per kilogram of body weight per day for five days, repeated every four to six weeks for up to 12 cycles). After a median follow-up of more than six years, there were no significant differences between the patients given no chemotherapy and those treated with melphalan with respect to either five-year disease-free survival (91 vs. 98 percent; P = 0.41) or overall survival (94 vs. 98 percent; P = 0.43). In the second trial, 141 patients with poorly differentiated Stage I tumors or with cancer outside the ovaries but limited to the pelvis (Stage II) were randomly assigned to treatment with either melphalan (in the same regimen as above) or a single intraperitoneal dose of 32P (15 mCi) at the time of surgery. In this trial (median follow-up, greater than 6 years) the outcomes for the two treatment groups were similar with respect to five-year disease-free survival (80 percent in both groups) and overall survival (81 percent with melphalan vs. 78 percent with 32P; P = 0.48). We conclude that in patients with localized ovarian cancer, comprehensive staging at the time of surgical resection can serve to identify those patients (as defined by the first trial) who can be followed without adjuvant chemotherapy. The remaining patients with localized ovarian cancer should receive adjuvant therapy, and with adjuvant melphalan or intraperitoneal 32P should have a five-year disease-free survival of about 80 percent.

Adult↗
PubMed1990

Bowel perforation associated with intraperitoneal chromic phosphate instillation.

Intraperitoneal chromic phosphate is widely used as adjuvant therapy in the treatment of early-stage ovarian epithelial carcinoma. Delayed bowel injury is an infrequently observed complication of chromic phosphate administration. This report presents a case of colon perforation which occurred 4 months after treatment with intraperitoneal chromic phosphate for stage IB ovarian papillary serous cystadenocarcinoma.

Chromium↗