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Biomedical subjects

R Novak

Publications and source records attributed to R Novak.

At least 55 records · Page 3Linked to original sources

The respiratory aspect of the treatment of brain injury associated with acute alcohol intoxication--results of an animal experiment.

The effects of spontaneous respiration and mechanical ventilation were examined by investigating the interaction between elevated intracranial pressure and alcohol intoxication. Ethanol (200 ml 48%) was infused in 11 young pigs with elevated cerebral pressure during mechanical ventilation (group 1), 7 young pigs with elevated cerebral pressure during spontaneous respiration (group 2), and 4 young pigs without elevated cerebral pressure during spontaneous respiration (group 3). While the behavior of intracranial pressure during mechanical ventilation in the animals from group 1 was inhomogeneous with a tendency to rise (29-34 mmHg), cerebral pressure (28-55 mmHg) increased drastically in the animals from group 2. This increase was associated with a sharp rise of Pa,CO2 (37.6-73.3 mmHg) and a decrease of Pa,O2 (74 mmHg to 13 mmHg). None of the animals in group 2 survived. Pa,CO2 also rose in alcoholized animals without elevated cerebral pressure (group 3) (41.9-63.9 mmHg); intracranial pressure, however, remained within the normal range. All animals in group 3 survived. Our findings indicate that elevated intracranial pressure and alcohol intoxication have a cumulative or potentiating effect on depression of the respiratory center. Respiratory depression can be prevented by mechanical ventilation and, therefore, a further rise of intracranial pressure generally avoided.

Alcoholic Intoxication↗

[Course of superficial carcinoma of bladder (Ta-T1). Apropos of 171 cases].

171 patients with superficial bladder carcinoma (Ta-T1) treatment by endoscopic surgery only, were followed during the period from 1.1.1976 to 31.12.1980. The effect of previous tumors in case history, multiplicity, cellular differentiation and tumor size on the frequency of recurrence and tendency to tumor progression was investigated. It was established that the size of tumor most influences the frequency of recurrence, followed by tumors in case history, multiplicity and epithelial anaplasia. A tendency to muscular invasion during recurrence depends mainly on the tumors size and its grade of cellular anaplasia.

Humans↗

An in vitro comparison of rat and chicken brain neurotoxic esterase.

A systematic comparison was undertaken to characterize neurotoxic esterase (NTE) from rat and chicken brain in terms of inhibitor sensitivities, pH optima, and molecular weights. Paraoxon titration of phenyl valerate (PV)-hydrolyzing carboxylesterases showed that rat esterases were more sensitive than chicken to paraoxon inhibition at concentrations less than or equal to microM and superimposable with chicken esterases at concentrations of 2.5-1000 microM. Mipafox titration of the paraoxon-resistant esterases at a fixed paraoxon concentration of 100 microM (mipafox concentration: 0-1000 microM) resulted in a mipafox I50 of 7.3 microM for chicken brain NTE and 11.6 microM for rat brain NTE. NTE (i.e., paraoxon-resistant, mipafox-sensitive esterase activity) comprised 80% of chicken and 60% of rat brain paraoxon-resistant activity with the specific activity of chicken brain NTE approximately twice that of rat brain NTE. The pH maxima for NTE from both species was similar showing broad, slightly alkaline optima from pH 7.9 to 8.6. [3H]Diisopropyl phosphorofluoridate (DFP)-labeled NTE from the brains of both species had an apparent mol wt of 160,000 measured by sodium dodecyl sulfate polyacrylamide gel electrophoresis. In conclusion, NTE from both species was very similar, with the mipafox I50 for rat NTE within the range of reported values for chicken and human NTE, and the inhibitor parameters of the chicken NTE assay were applicable for the rat NTE assay.

Animals↗

Directed manual recruitment of collapsed lung in intubated and nonintubated patients.

Four patients with collapsed lung are presented that demonstrate the utility of the directed manual recruitment technique (DMRT) in a range of clinical situations presented by weaning difficulties, recurrent acute atelectasis, and acute respiratory failure in the nonintubated patient. DMRT is an easily applied noninvasive method of lung expansion in the treatment of patients with segmental and lobar collapse and is safe when carried out with appropriate precautions.

Adult↗

Surgical treatment of urethral stricture: still a problem?

In the introduction the author stresses that the main facts which decide the choice and prognosis of therapy are localization, length and the so-called complexity of the stricture. His 15-year material from 388 operations on 290 patients is presented. Circular strictures of the anterior urethra (a total of 135 operations) are treated through endoscopic urethrotomy as the primary procedure and mostly by open resection as the secondary one. Longitudinal strictures of the anterior urethra (199 operations) are treated by marsupialization, pedicled cutaneous flap and Michalowski's "sleeve" technique as primary procedures. As the secondary procedure (after failure of the first operation) marsupialization only was performed. Complex strictures of the posterior urethra (total 54) were treated mostly by transpubic approach, which showed good results in 74% cases on 41 operations.

Endoscopy↗

Effect of methylazoxymethanol acetate on rat liver nuclear and nucleolar RNA synthesis.

The effect of methylazoxymethanol acetate on rat liver nuclear and nucleolar RNA synthesis is investigated at various doses (5 to 50 mg/100 g body weight) and for various lengths of time (1 to 24 hr). The results show that this carcinogen is a potent inhibitor of both nuclear and nucleolar RNA synthesis. Like other carcinogens studied previously in this laboratory, e.g., N-hydroxy-2-acetylaminofluorene, aflatoxin B1, and actinomycin D, methylazoxymethanol acetate inhibits RNA synthesis at multiple sites. It impairs chromatin template function and selectively inhibits the activity of RNA polymerase II. Experimental evidence suggests the mechanism of inhibition of RNA polymerase II activity is due to a decrease in catalytic efficiency rather than in the total number of the enzyme. In addition, it is found that methylazoxymethanol acetate induces a dramatic condensation of nucleoplasmic chromatin.

Animals↗

[Current status of transpubic surgery of the posterior urethra].

The transpubic approach is indicated for repair of complex stenoses of the posterior urethra, fundamental technical points being perineal mobilization of the anterior urethra, dissection of the intercrural septum, symphyseotomy, and direct anterior anastomosis of the two extremities of the urethra. Analysis of results in a personal series of 49 patients operated upon for posterior urethral stenosis showed that good results were obtained in 35 cases (71%), no postoperative endoscopic or surgical procedure being necessary. However, recurrence of the lesion was noted in 6 cases (12%), absolute incontinence following operation in 3 cases (6%), and relative incontinence in 5 cases (10%). Postoperative sexual disorders developed in 11 adults, 8 of these reporting various types of erection difficulties.

Humans↗

Cytokinetically based induction chemotherapy and splenectomy for childhood acute nonlymphocytic leukemia.

A four-drug regimen, based on cell kinetic principles, induced complete remissions in 68 of 95 children (72%) with acute nonlymphocytic leukemia (ANLL). Patients entered remission after 2-5 weekly cycles of vincristine-daunorubicin (day 1) followed by sequential cytosine arabinoside and 6-azauridine (days 4-7). With continuation therapy of monthly vincristine-doxorubicin-cyclophosphamide, weekly cytosine arabinoside, and daily 6-mercaptopurine, the median duration of complete remission was 10 mo and the median survival time 21 mo. Portal triaditis, evident in 11 of 23 patients with liver biopsies, was associated with long remissions. A larger spleen size (greater than 5 cm) and a higher myeloblast labeling index (greater than 10%) at diagnosis were clearly related to shorter durations of remission. Splenectomy within 1 mo of remission had no statistically significant effect on the frequency of relapse or length of remission. Patients without central nervous system (CNS) leukemia at diagnosis, all treated prophylactically with intrathecal methotrexate, had a low frequency of initial CNS relapse (3/56, 5%). The 2-yr disease-free survival rate is 29% (20 of 68 patients attaining complete remission). fifteen patients have completed 2.5 yr of therapy, and each remains in continuous complete remission, off treatment, for 1+ -36+ mo. This induction chemotherapy was as effective as more intensive regimens, with the advantage of less toxicity and shorter periods of hospitalization.

Acute Disease↗

Antireflux ureteroileosigmoidostomy by means of ileal intussusception.

Ureteroileosigmoidostomy is recommended for supravesical urinary diversion after cystectomy. Wallace's method for the ileal conduit with a terminal nipple is employed, but the ileal segment is anastomosed to the rectosigmoid instead of the abdominal wall. In this way, the nipple on the distal end of the ileal segment protrudes into the lumen of the large bowel rather than into the abdominal wall, preventing therefore sigmoidoilal reflux. Radical cystectomy has been supplemented with this procedure for urinary diversion in 29 patients with bladder carcinoma.

Colon, Sigmoid↗