Problem-based clinical confrontation modules planned and conducted by students

A course has been described which attempts to introduce clinical relevancy to the basic science knowledge. It has been demonstrated how senior students' feedback about curricular shortcomings can be redirected to their constructive participation in the educational process. The described Clinical Confrontation course develops problem-solving skills and self-learning habits in the learners while they are processing and rearranging prior knowledge. At the same time, both the scientific base of medicine and the internal logic of the disciplines are preserved.

Pharmacokinetic analysis of sustained-release dosage forms of theophylline in humans: comparison of single and multiple dose studies

A pharmacokinetic analysis of two sustained-release dosage forms of theophylline (Theo-Dur and Theotrim) was carried out following single and multiple dose administrations of the two formulations in five healthy subjects. Despite the prolonged absorption after administration of the two sustained-release formulations, theoretical predictions of theophylline steady-state levels following multiple dosages based upon data obtained from the single dose study, correlated with the data of the multiple dose study. This study shows that the recommended dose and dosage regimen of new sustained-release formulations of theophylline can be based upon single dose studies. In the population studied, repetitive doses of 450 mg b.i.d. of Theo-Dur and Theotrim maintain steady-state concentrations of theophylline within the drug's therapeutic window.

Treatment of spastic dysphonia without nerve section

Spastic dysphonia is a disorder characterized by strained, constricted phonation with excessively adducted vocal cords. Despite initial success with recurrent laryngeal nerve section, the search for other treatment continues. Our clinical study involved inserting a needle electrode percutaneously into the region of the recurrent laryngeal nerve in five patients with spastic dysphonia. Electrical stimulation resulted in dramatic improvement in three patients and minimal improvement in two. Our experimental study was designed to create an animal model for an implantable nerve stimulator to be used on a long-term basis. A Medtronic spinal cord stimulation system was implanted into a dog, and a cuff electrode was positioned around the recurrent laryngeal nerve. Vocal cord position could be altered by varying the stimulus frequency. Long-term stimulation of the recurrent laryngeal nerve was relatively safe and effective. Eventually, we plan to implant nerve stimulators into spastic dysphonia patients who respond well to percutaneous stimulation.

Effect of discontinuance of type A behavioral counseling on type A behavior and cardiac recurrence rate of post myocardial infarction patients

Three hundred post infarction participants who had received type A behavioral counseling in the Recurrent Coronary Prevention Project, (RCPP) agreed to be followed for 1 additional year after stopping 4.5 years of continuous type A behavioral counseling. One hundred fourteen participants who had served for 4.5 years as controls in the RCPP Study, thus receiving no type A behavioral counseling, volunteered to receive such counseling for 1 year. Eleven of the 300 previously type A counseled RCPP participants were lost to follow-up at the end of the additional year. The remaining 289 subjects at risk were found to have maintained their previously reduced intensity of type A behavior. Their previously observed relatively low cardiac recurrence rate during the additional year also did not significantly change. Ten of the 114 previous control RCPP participants were lost to follow-up at the end of the additional year. The remaining 104 subjects who had received a year's type A behavioral counseling showed a significantly reduced intensity of type A behavior and a similar significant decrease in both the cardiac mortality and morbidity rate. These results suggest that the decline in the intensity of type A behavior and also in the cardiac recurrence rate previously observed in post infarction subjects exposed to type A behavioral counseling persists for at least 1 year after cessation of such counseling.

The effects of ionizing radiation on the pulmonary vasculature of intact rats and isolated pulmonary endothelium

We studied the effects of ionizing radiation on the morphology of the pulmonary circulation using an in vivo rat model and an in vitro pulmonary artery endothelial cell model. Gamma radiation was given as either an acute (30 Gy) or fractionated (5 X 6 Gy) dose to one hemithorax of rats. An acute 30-Gy dose delivered resulted in a 70% decrease in pulmonary arterial perfusion, using technetium-99m microaggregated albumin (99mTc-MAA), in the irradiated lung by 2-3 weeks after irradiation. Pulmonary microradiographs, using a barium sulfate perfusion method, obtained 2-3 weeks after irradiation demonstrated widespread loss of capillary filling and segmentation of the vessels. Histologic examination demonstrated intact capillaries, suggesting that the alterations in pulmonary perfusion were at the precapillary level. Similar abnormalities in lung perfusion and morphology were found after delivery of fractionated doses of radiation, but the onset of the changes was delayed, occurring 4-6 weeks postirradiation. Using cultured pulmonary endothelial cell monolayers, cell sloughing and retraction from the surface substrate were observed within 24 h after in vitro delivery of 30 Gy. Similar findings occurred in monolayers given fractionated doses (5 X 6 Gy) of radiation 2-3 days after the final dose. The in vivo animal and in vitro endothelial cell models offer a useful means of examining the morphologic alterations involved in radiation lung vascular damage.

Anterior glossectomy: reconstruction with a posterior tongue rotation flap

With traditional techniques, reconstruction of the anterior tongue is often less than satisfactory. The difficulty lies mainly in providing the tongue with the appropriate amount of bulk essential for normal movement and function. We present an alternative method that involves raising a flap from the ipsilateral middle third of the tongue and rotating it into position for suturing to the anterior defect border. We have found this simple procedure to yield adequate tongue bulk for normal speech and deglutition.

The bilobed deltopectoral advancement flap

The bilobed deltopectoral advancement flap is a versatile reconstructive option for selected cervical defects. This modified version of Bakamjian's classic deltopectoral flap utilizes thin anterolateral neck skin to cover complex anterior neck defects. It offers the safety of a minimally rotated pedicle to reduce the chance of flap necrosis from kinking, and the convenience of a single-stage procedure. We have used this flap six times in our clinical experience. Typically, the defects were located in the anterior cervical region, and many of them were reconstructed following total laryngectomy and radical neck dissection. There was no incidence of flap necrosis in the patients, including those who had had preoperative irradiation.

Effect of sulfur amino acid supplementation of raw soy flour on the growth and pancreatic weights of rats

Rat feeding studies showed that L-cystine, L-cysteine, N-acetyl-L-cysteine and L-methionine enhance the nutritional quality of raw (unheated) soy flour as measured in rats by the protein efficiency ratio (PER). Pancreas weights of rats fed diets supplemented with sulfur amino acids were higher than those of rats fed unsupplemented diets. In some instances this increase resulting from nutritional improvement of the diet was relatively greater than that in total body weight. Explanations are offered for these effects in terms of the proposed biofeedback mechanism involving the gastrointestinal endocrine system and the hormone cholecystokinin. The observed stimulation of pancreatic growth by added sulfur amino acids may be closely associated with this pancreatic regulatory mechanism when activated in response to dietary trypsin inhibitors present in unheated soy protein. The extent to which pancreatic hypertrophy develops as a result of a given exposure to trypsin inhibitors may be limited when the total amount or quality of the protein in the diet is less than optimal.

Mesenteric venous thrombosis associated with pregnancy and oral contraception. A case report

Mesenteric vein thrombosis in a pregnant woman taking an oral contraceptive is reported. It is presumed that the hypercoagulable state of pregnancy combined with hormonal contraception led to the thrombosis.

Evaluating the Use of a Data Base System With Community Health Nursing Students

The Data Base Management System for community diagnosis was used during two academic semesters with 80 baccalaureate nursing students. At the end of the two semesters the DBMS was evaluated from feedback obtained through faculty discussions, final student papers and oral presentations. The DBMS met the goals established to evaluate the tool. The clarification of categories for essential data is an ongoing process.

Benign neoplasms of the oral cavity

A wide variety of benign tumors present in the oral cavity. These tumors are for the most part rare and are classified by the tissue of origin. Although benign oral cavity tumors are not life-threatening, they can result in extensive loss of soft tissue and/or bone. Furthermore, many patients are subject to the threat of recurrence, multiple surgical procedures, and the possibility of malignant degeneration. Because many tumors vary little clinically, an adequate biopsy specimen must be obtained for diagnosis. Radiographs are, in general, nondiagnostic. Collaboration with an experienced pathologist is necessary to determine the tumor's probable clinical behavior. Therapy, which is dictated by tumor type, is almost always surgical.

Reduced oxygen tension induces pulmonary endothelium to release a pulmonary smooth muscle cell mitogen(s)

Bovine pulmonary endothelial cells grown in vitro were shown to release a factor that was mitogenic for pulmonary smooth muscle cells during exposure to a reduced oxygen tension atmosphere. The addition of hypoxic endothelium-derived medium resulted in a 60% increase in smooth muscle cell number after 24 h of exposure. Addition of medium from pulmonary endothelium exposed to normoxic conditions or medium derived from either hypoxic or normoxic aortic endothelium did not result in significant increases in smooth muscle cell number. Physicochemical characterization of the hypoxic pulmonary endothelial cell-derived factor(s) showed that it was resistant to heat and reducing agent treatment and stable between pH 3 and 10. The mitogenic activity decreased by 71% at pH 2 and by 68% after treatment with trypsin. The activity adhered to DEAE Sephadex. Gel filtration chromatography of the hypoxic-conditioned medium demonstrated 2 major peaks of smooth muscle cell growth factor activity corresponding to molecular weights between 6,000 and 14,000 and 20,000 and 65,000 daltons, respectively. These data suggest that this pulmonary endothelial cell-derived smooth muscle cell peptide mitogen(s) may be involved in the smooth muscle cell proliferative response seen with chronic alveolar hypoxia.

Nutritional value and safety in mice of proteins and their admixtures with carbohydrates and vitamin C after heating

When a nutritionally complete basal diet containing 10% protein from casein was supplemented with 20% protein from unheated casein, wheat gluten or soy protein isolate, weanling mice exhibited significantly increased weight gains. In contrast, weight gains were markedly reduced compared to those with the basal diet; that is, growth was inhibited, when the supplement was soy protein or gluten that had been heated at 200 or 215 degrees C for 72 min in the dry state to stimulate crust baking. Addition of various carbohydrates to the gluten during heating prevented such growth inhibition. After heating with sodium ascorbate (but not L-ascorbic acid), soy protein (at 200 degrees C) and gluten (at 215 degrees C) completely prevented growth when added to the basal diet. Growth inhibition also occurred with a heated casein-ascorbate mixture, but was less than with the other proteins. The extent of growth inhibition increased sharply with temperature of heating in the range 180-215 degrees C and with sodium ascorbate concentration in the range 1-20%. Possible physical and chemical changes during heating of protein-ascorbate mixtures are discussed, as are possible mechanisms for the growth inhibition.

Sternomastoid myoperiosteal flap for reconstruction of the subglottic larynx

Reconstruction of the subglottis is usually required after resection of cricoid cartilage or tracheal tissue in cases of trauma, subglottic stenosis, or invasive thyroid carcinoma. There are multiple techniques available for reconstruction of the subglottic larynx, but most of them have a high rate of complications or graft failure. We have found the sternocleidomastoid myoperiosteal flap to be an ideal means of reconstruction. In an experimental study, we performed subglottic reconstruction using the sternomastoid myoperiosteal flap on 15 mongrel dogs to determine the presence of bone formation versus calcified fibrous scar. Radiologic studies suggested apparent metaplastic bone formation at the graft site, and histologic studies confirmed this. Functionally, 12 dogs had stable airways without stridor or subglottic narrowing. Three dogs died of complications. With successful reconstruction of large defects in the canine subglottis, attempts to repair large subglottic and tracheal defects in the human are feasible.

Acute cardiovascular and pulmonary effects of intravenous and aerosolized amiloride in the dog

Active Na+ absorption by the epithelia that line the airways can drive volume from the airway surface. Exposure of the lumen-facing surface of airway epithelia to amiloride inhibits Na+ transport. Consequently, aerosolized amiloride may help hydrate the desiccated surface liquid that characterizes lung diseases such as cystic fibrosis. We studied the acute cardiovascular and pulmonary effects of amiloride in anesthetized dogs. Intravenous amiloride reduced blood pressure and increased ventilation frequency and airways resistance of the dog. The effects were dose-related (ED50 = 1.3 X 10(-6) mol/kg), resembled those of injected histamine, and were antagonized by methapyrilene. These results were compatible with the release of endogenous histamine by amiloride, but the graded dose-effect relationship for amiloride differed from the quantal relationship induced by the prototypical releaser, 48/80. Aerosolization of a Ringer's solution that was nearly saturated with amiloride deposited, in upper airway surface liquid, drug concentrations which in previous studies, were sufficient to inhibit Na+ transport by canine airways (ED50 approximately 10(-6) M). Cardiovascular function, airways resistance, and indices of pulmonary tissue water, gas exchange, and perfusion were not affected. Since circulating amiloride after aerosolization was estimated to fall below the concentration that induced vasodepression and correct circled bronchoconstriction after intravenous injection, we conclude that the potency of aerosolized amiloride to induce acute effects in tissues other than airway epithelia is no greater than that of intravenous drug.

Difficult decisions in parotid surgery

Six atypical case presentations of parotid tumors are presented along with solutions proposed by two experts on the topic. The differences and similarities of the opinions expressed are summarized and discussed by the editor.

Surgical treatment of hyperparathyroidism

During the past decade, major advances have been made in many crucial areas of the surgical management of hyperparathyroidism. An up-to-date protocol is presented and stresses preoperative localization, operative technique, intraoperative diagnosis, cryopreservation, and autotransplantation designed for practical application.

Reversible alterations in cultured pulmonary artery endothelial cell monolayer morphology and albumin permeability induced by ionizing radiation

The effects of ionizing irradiation (0, 600, 1,500, or 3,000 rads) on the permeability of pulmonary endothelial monolayers to albumin were studied. Pulmonary endothelial cells were grown to confluence on gelatin-coated polycarbonate filters, placed in serum-free medium, and exposed to a 60Co source. The monolayers were placed in modified flux chambers 24 hours after irradiation; 125I-albumin was added to the upper well, and both the upper and lower wells were serially sampled over 4 hours. The amount of albumin transferred from the upper well/hour over the period of steady-state clearance (90-240 min after addition of 125I-albumin) was 2.8 +/- 0.2% in control monolayers and was increased in monolayers exposed to 1,500 or 3,000 rads (increase of 63 +/- 10% and 61 +/- 10%, respectively, P less than 0.01). No increase was found in monolayers exposed to 600 rads. The increases in endothelial albumin transfer rates were associated with morphologic evidence of monolayer disruption and endothelial injury which paralleled the changes in albumin permeability. Dose-dependent alterations in endothelial actin filament organization were also found. Incubation of the monolayers exposed to 3,000 rads with medium supplemented with 10% fetal calf serum for 24 hours resulted in normalization of albumin permeability, improvement in morphologic appearance of the monolayers, and reorganization of the actin filament structure. These studies demonstrate that ionizing radiation is an active principle in the reversible disorganization of cultured pulmonary endothelial cell monolayers without the need of other cell types or serum components.