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Biomedical subjects

R D Barnes

Publications and source records attributed to R D Barnes.

At least 19 recordsLinked to original sources
PubMed2001

Nitric oxide modulates evoked catecholamine release from canine adrenal medulla.

Nitric oxide has various actions, acting in a neurotransmitter-like role and also as a paracrine messenger between vascular endothelial and smooth muscle cells. This study was done to determine whether endogenous nitric oxide has a role in modulating evoked catecholamine release from the canine adrenal medulla. Isolated adrenal glands were perfused with Krebs-Ringer solution as a control, or with Krebs-Ringer solution containing either N(G)-monomethyl-L-arginine (L-NMMA; 3x10(-4) M) to non-selectively inhibit nitric oxide synthase or 7-nitroindazole (10(-4) M), a relatively selective inhibitor of neuronal nitric oxide synthase. Catecholamine release was evoked using the nicotinic cholinergic agonist 1,1-dimethyl-4-phenylpiperazinium iodine. From the collected perfusate epinephrine, norepinephrine, and dopamine were measured by high performance liquid chromatography. Previous studies have shown that in the presence of L-NMMA, basal releases of epinephrine, norepinephrine and dopamine are increased. 7-Nitroindazole had no effect on basal catecholamine release, suggesting that nitric oxide from an endothelial source was responsible for the inhibition of basal catecholamine release from the adrenal medulla. Epinephrine and norepinephrine releases were augmented when either of the nitric oxide synthase inhibitors was added during submaximal nicotinic stimulation, indicating that endogenous nitric oxide inhibited release of epinephrine and norepinephrine. Both neuronal and endothelial nitric oxide synthases appeared to be responsible for this inhibition. In summary, these studies suggest that nitric oxide, from both neuronal and endothelial sources, modulates evoked catecholamine release from canine adrenal medulla, while nitric oxide from an endothelial source is most likely responsible for modulation of catecholamine release under basal conditions.

Adrenal Medulla↗
PubMed2000

Microsatellite analysis of Pinus taeda L. in Zimbabwe.

Deducing the origin of early 20th century introductions of Pinus taeda into Zimbabwe is possible given microsatellite markers and clear population differentiation in ancestral U.S. populations. This study was designed to determine whether P. taeda introductions into Zimbabwe came from one U.S. region or whether the present-day population is an admixture of introductions from east and west of the Mississippi River Valley. Principal components analysis, Cavalli-Sforza and Edwards' chord distances and presence of diagnostic alleles each indicate that the Zimbabwe population is an admixture. There were five novel alleles in the Zimbabwe population not represented in the indigenous U.S. populations, possibly because of de novo mutation, introgression with other introduced North American pines or sampling error.

Alleles↗
PubMed1998

Radical cystectomy for invasive bladder cancer--a local experience.

OBJECTIVES: The aim of this study of patients undergoing cystectomy for invasive transitional cell carcinoma of the bladder was to compare clinical and pathological staging and to review factors that predict survival. PATIENTS: Sixty-three patients (73% male) underwent radical cystectomy between January 1988 and February 1994. The mean age was 61 years (range 33-77 years). RESULTS: Of the patients 14% had clinical and 24% pathological stage T1 disease; figures for T2 disease were 24% and 6%, respectively, for T3 disease 46% and 45%, and for T4 disease 16% and 25%. For T1 and T4 disease the clinical stage predicted the pathological stage in over 80% of cases, and for patients with T3 disease the predictive value of clinical staging was 68%; in no patient with clinical stage T2 disease was this confirmed at cystectomy. The prevalence of tumour infiltration of the lymph glands on histological examination of the cystectomy specimen correlated more closely with pathological stage than with clinical stage. For clinical and pathological staging, respectively, the prevalences were 0% and 0%, for T1, 27% and 0% for T2, 20% and 29% for T3, and 40% and 38% for T4. The overall survival rate (life-table method) was 33% at a median follow-up of 42 months in the surviving patients. No patient with tumour infiltration of the lymph glands survived. Survival also correlated more closely with pathological than with histological stage. For clinical and pathological stage T1 disease the 5-year survival rates were 73% and 91%, respectively; for T2 the rates were 27% and 75%, for T3 32% and 31%, and for T4 28% and 29%. The operative mortality rate was 2% and the rate of recurrence of local disease 10%. CONCLUSIONS: Survival after cystectomy correlates more closely with pathological than with clinical stage of disease. The accuracy of clinical staging in T2 disease is poor. Cystectomy is the standard against which other treatments for bladder cancer must be measured.

Adult↗
PubMed1997

Primary chemotherapy for stage 2 testis cancer.

To evaluate the efficacy and toxicity of primary chemotherapy in patients with stage 2 (retroperitoneal lymph node metastases) testis cancer, 20 consecutive patients referred to Groote Schuur Hospital between September 1992 and March 1994 were reviewed. There were 10 patients with non-bulky non-seminomatous germ cell tumour (NSGCT), 5 with bulky NSGCT and 5 with bulky seminoma. The treatment regimen consisted initially of 4 cycles of cisplatin, etoposide and bleomycin. Patients with NSGCT and a residual mass after chemotherapy subsequently underwent retroperitoneal lymph node dissection (RPLND) and those with seminoma underwent a low dose of irradiation to the mass. In 7 (70%) of the 10 patients with non-bulky NSGCT, there was a complete response to chemotherapy and 3 patients underwent limited RPLND. One patient relapsed at follow-up but remains clear of disease after salvage therapy. The survival rate is 100% at a median follow-up of 60 months (range 12-143 months). In 5 patients with bulky NSGCT there was no complete response to chemotherapy. Three have undergone limited RPLND. The survival rate is 52% at a median follow-up of 130 months (range 108-152 months). In 5 patients with bulky seminomas, the survival rate is 100% at a median follow-up of 55 months (range 29-92 months). Toxicity has been modest except for 1 patient who died postoperatively in the early part of the study. Four patients have fathered children after treatment. We conclude that primary chemotherapy is the treatment of choice for patients with stage 2 testis cancer.

Adolescent↗
PubMed1996

Perioperative respiratory complications in patients with asthma.

BACKGROUND: Patients with asthma are thought to be at high risk for pulmonary complications to develop during the perioperative period, and these complications may lead to serious morbidity. Existing medical records were reviewed to determine the frequency of and risk factors for perioperative pulmonary complications in a cohort of residents of Rochester, Minnesota, who had asthma and who underwent anesthesia and surgery at the Mayo Clinic in Rochester. METHODS: Medical records were reviewed for all residents of Rochester, Minnesota, who were initially diagnosed as having definite asthma according to strict criteria from 1 January 1964 through 31 December 1983 who subsequently had at least one surgical procedure involving a general anesthetic or central neuroaxis block at the Mayo Clinic (n = 706). RESULTS: Bronchospasm was documented in the perioperative records of 12 patients (1.7% [exact 95% confidence interval, 0.9 to 3%]). Postoperative respiratory failure developed in one of these patients. Laryngospasm developed in two additional patients during operation. All episodes of bronchospasm and laryngospasm in the immediate perioperative period were treated successfully. No episodes of pneumothorax, pneumonia, or death in the hospital were noted. For univariate analysis, characteristics associated with complications included the recent use of antiasthmatic drugs, recent asthma symptoms, and recent therapy in a medical facility for asthma. Patients in whom complications developed were significantly older at diagnosis and at surgery. CONCLUSIONS: The frequency of perioperative bronchospasm and laryngospasm was surprisingly low in this cohort of persons with asthma. These complications did not lead to severe respiratory outcomes in most patients. The frequency of complications was increased in older patients and in those with active asthma.

Adolescent↗
PubMed1995

Emphysematous pyelonephritis in diabetic patients.

OBJECTIVE: To determine the clinico-pathological profile of patients with emphysematous pyelonephritis (EPN). PATIENTS AND METHODS: The records of 22 diabetic patients who presented with EPN were reviewed. RESULTS: EPN occurred predominantly in female diabetic patients without evidence of ureteric obstruction. The ages of the patients and the duration of the diabetes were variable. EPN occurred in insulin-dependent as well as non-insulin-dependent patients. The patients presented following a prodromal illness of urinary sepsis, with an acute severe illness with symptoms and signs on the affected side. Dehydration and ketoacidosis were common. The diagnosis was made by recognizing gas in the kidney on an X-ray or ultrasound. Eighteen patients were subjected to emergency nephrectomy. CONCLUSIONS: EPN is an uncommon, life-threatening condition characterized by the production of intraparenchymal gas. We believe that vigorous resuscitation and emergency nephrectomy is the treatment of choice.

Adult↗
PubMed1994

Antiviral therapy after penetrating keratoplasty for herpes simplex keratitis.

OBJECTIVE: To assess the efficacy of prophylactic topical antiviral therapy after penetrating keratoplasty for herpes simplex keratitis in the postoperative period and during the treatment of allograft rejection episodes with topical steroids. We used these data to make predictions of the sample size required to perform a prospective study of prophylactic oral acyclovir in the postoperative period. DESIGN: Retrospective review. SETTING: A university referral cornea service. PATIENTS: One hundred thirty-two consecutive penetrating keratoplasties for herpes simplex keratitis in 119 eyes of 118 patients. Only four grafts were performed in actively inflamed eyes. INTERVENTIONS: Sixty-six (52%) of the grafts performed in quiescent eyes received prophylactic postoperative topical antiviral treatment, three (2%) received oral acyclovir, and 59 (46%) received no antiviral therapy. The mean (+/- SD) duration of antiviral therapy was 12.8 +/- 22.5 months. MAIN OUTCOME MEASURES: Herpetic recurrence, allograft rejection episodes, and graft failure. RESULTS: Multivariate analysis showed that early antiviral use was associated with a decreased risk of herpes simplex keratitis recurrence (relative risk [RR] = 0.44; 95% confidence interval [CI], 0.21 to 0.94; P = .007) and allograft rejection (RR = 0.43; 95% CI, 0.25 to 0.75; P = .002). Graft failure was associated with herpetic recurrence within the first year (RR = 2.25; 95% CI, 1.09 to 4.64; P = .001) and allograft rejection episodes (RR = 2.56; 95% CI, 1.20 to 5.26; P = .003). Using these data, a prospective trial of postoperative oral acyclovir would require between 59 and 112 patients per group. CONCLUSIONS: Postoperative prophylactic antiviral treatment is associated with decreased rates of herpes simplex viral keratitis recurrence and allograft rejection. Early recurrence is associated with an increased risk of graft failure. A prospective study of postoperative oral acyclovir would require a multicentered approach.

Acyclovir↗
PubMed1994

Adjuvant chemotherapy for stage I non-seminomatous testicular cancer.

Developments in the treatment of stage I testicular non-seminomatous germ cell tumours have aimed primarily at reducing morbidity since the introduction of retroperitoneal lymph node dissection. Surveillance after orchidectomy, i.e. follow-up alone with chemotherapy only for relapsed disease, was found to be logistically and psychologically taxing for patients. Risk factors for relapse were, however, identified from analyses of tumour histology of the orchidectomy specimen. Between September 1988 and April 1992, 20 patients with clinical stage I testicular non-seminomatous germ cell tumours and a relatively high risk of relapse were entered into a prospective study of adjuvant chemotherapy. The chemotherapy regimen consisted of 2 cycles of cisplatin, etoposide and bleomycin. Each cycle of chemotherapy lasted 3 days. There have been no relapses at a median follow-up of 31 months (range 12-53 months). Acute and late toxicity have been modest. We have found adjuvant chemotherapy to be effective after orchidectomy in patients with stage I disease with adverse prognostic factors for relapse.

Adult↗
PubMed1994

Interpractice visits by general practitioners.

Most of the objectives have thus been successfully met as the interpractice visits have proven to be a well accepted form of self-regulated implicit peer review activity among GPs, continuing with enthusiasm on the part of the participants over a period of five years and now propagating nationally. Significant to the success is the ownership of the scheme by the participants. The advent of QA and CE credit points can only enhance participation rates. Continuing attention to the principles of audit, namely evaluation, change and review, will refine the method in the future into an even more effective tool, which can be recommended to all those in general practice. A necessary area for attention in the future is effective outcome evaluation.

Australia↗
PubMed1994

Neo-adjuvant chemotherapy and radical irradiation for locally advanced bladder cancer--a phase 2 study.

Eighteen patients with T3 or T4 bladder cancer were treated with neo-adjuvant chemotherapy and radical irradiation. The tumour response was assessed after two cycles of chemotherapy and two further cycles of chemotherapy were given to patients with responding tumours. Each cycle of chemotherapy consisted of cisplatin (60 mg/m2) as well as methotrexate and vinblastine. After chemotherapy, a complete response (CR) was obtained in four (22%) patients and a partial response in eight (44%) of patients. After irradiation, a complete response was obtained in 12 (67%) patients. Four of the 12 patients who achieved a CR relapsed at a minimum follow-up of 3 years. The 3-year continuously disease-free survival rate (with preserved bladders) is 44%. (95% confidence interval = 21-65%.) Altogether, 11 patients are alive (including three who have undergone salvage cystectomy) for an overall 3-year survival rate which is 61%. This approach to therapy is feasible but the local control rate is unsatisfactory.

Aged↗
PubMed1993

Salvage cystectomy after radical irradiation for bladder cancer-prognostic factors and complications.

We have studied 46 patients who underwent salvage cystectomy between March 1981 and June 1992 for persistent or recurrent carcinoma after radical irradiation for bladder carcinoma. The overall 5-year survival rate was 43%. There was a higher 5-year survival rate in patients with an incomplete response compared with those with a complete response to their prior irradiation (50 and 36%), in patients with grades 1 or 2 compared with grade 3 histology (75 and 28%), and in patients with T1 or T2 tumours compared with T3 tumours (59 and 32%). The median interval between commencing irradiation and performing cystectomy was 11 months. In the 25 patients with a prior complete response the median interval was 16 months; this was statistically significantly longer than in the 21 patients with an incomplete response (median interval 7 months). A worsening of tumour grade and category was found in some patients when comparing the findings at cystectomy with those prior to irradiation. This was consistently higher in patients with a prior complete response than in those with an incomplete response. There were 3 deaths and 12 non-fatal major complications due to the prior irradiation or surgery, with a mortality rate of 7% and an overall 5-year complications rate of 35%. Only one of the complications occurred in the 13 patients treated with conventional 2 Gy fractions alone (5 fractions/week). Their overall complication rate was statistically significantly lower than that of the others. Salvage cystectomy is indicated for selected patients with persistent or recurrent disease after radical irradiation for bladder cancer. The expectation of a survival rate similar to that found in patients treated with immediate cystectomy may not be justified.

Adult↗
PubMed1993

Chemotherapy, radical irradiation plus salvage cystectomy for bladder cancer--severe late small bowel morbidity.

A proportion of patients with invasive bladder cancer are treated with radical irradiation and salvage cystectomy. The use of neo-adjuvant chemotherapy is being widely investigated. Five patients with invasive bladder cancer at Groote Schuur Hospital have undergone salvage cystectomy after neo-adjuvant chemotherapy and radical irradiation. Two of these patients had severe small bowel morbidity while clear of carcinoma and this was fatal in one patient. In our historical series of 30 patients who had salvage cystectomy after radical irradiation alone, there was only one patient with similar small bowel morbidity. There may be an increase in small bowel morbidity from neo-adjuvant chemotherapy in patients who are treated to clinical tolerance by irradiation and who then require a cystectomy.

Adult↗
PubMed1989

Carcinoma of the penis--the Groote Schuur Hospital experience.

The records of 62 patients with carcinoma of the penis seen at Groote Schuur Hospital between 1968 and 1985 were analysed retrospectively. Jackson's staging system was used - 44% of patients were stage 1, 27% stage 2, 19% stage 3 and 10% stage 4. The results of treatment in each stage are outlined. Overall 65% of patients were alive and free of disease at follow-up while 24% died. The overall five-year survival rate was 56%. The management of the inguinal nodes is discussed. Early sentinel node biopsy is recommended, as clinical inguinal node assessment is inaccurate and late detection of inguinal node metastases is associated with a poor prognosis.

Adolescent↗