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Biomedical subjects

M Friedman

Publications and source records attributed to M Friedman.

At least 415 records · Page 23Linked to original sources
PubMed1984

Fluoride enhancement of chlorhexidine uptake by hydroxyapatite and enamel powders.

The purpose of the present study was to examine the in vitro adsorption of chlorhexidine and fluoride to hydroxyapatite and tooth enamel powders. Samples of hydroxyapatite or enamel powder were suspended in aqueous solutions of chlorhexidine gluconate 2.0; chlorhexidine acetate 1.5%; sodium fluoride of various concentrations (0.2%, 1%, 2%) and mixtures of sodium fluoride and chlorhexidine. The data obtained in the study show that chlorhexidine and fluoride adsorb to hydroxyapatite and tooth enamel in vitro. Furthermore, the amount of fluoride adsorbed to hydroxyapatite is reduced in the presence of chlorhexidine in the solution. A probable explanation for this effect may be that there is a competitive adsorption of fluoride and chlorhexidine on to the same binding sites on the hydroxyapatite. Additionally, the presence of fluoride dramatically increases the affinity of chlorhexidine for hydroxyapatite. The fact that fluoride strongly enhanced the adsorption of chlorhexidine to hydroxyapatite and enamel, indicates that fluoride may be of clinical interest beyond the prevention of caries.

Adsorption↗
PubMed1984

New sustained release dosage form of chlorhexidine for dental use: use for plaque control in partial denture wearers.

The aim of this work was to test the effectiveness of a local sustained release application of chlorhexidine in prevention of plaque formation in a group of five partial denture wearers when oral hygiene procedures were withdrawn. The clinical study demonstrates that coating of the partial dentures with ethyl cellulose polymer containing the drug, prevents accumulation of plaque during a period of 12 days. No typical side effects of chlorhexidine such as tooth staining and unpleasant taste were observed during the study.

Aged↗
PubMed1984

Enamel dissolution and fluoride uptake from sugar solutions.

Solubility studies and fluoride uptake by enamel powder in xylitol-buffered solutions versus sucrose- and glucose-buffered solutions were carried out. The studies were done at a pH range of 4-8. The enamel solubility in the xylitol media was similar to the enamel solubility in the other sugar solutions--increasing with a decreasing pH. The solubility of enamel in the buffered sugar solutions was significantly lower as compared to the solubility in the sugar-free buffered solutions--up to the pH of 6. At the pH values of 7 and 8 the amounts of solubility were similar for the experimental and control solutions. No significant differences were found in the fluoride uptake by the enamel powder from the fluoride-containing sugar solutions at the pH values of 6 and 7.5 respectively. The results point to the conclusion that the xylitol does not differ from sucrose and glucose in its effect on enamel powder solubility and the uptake of fluoride ions by enamel.

Carbohydrate Metabolism↗
PubMed1984

Effect of ventilation and perfusion imbalance on inert gas rebreathing variables.

The effects of ventilation-to-perfusion (VA/Qc) maldistribution within the lungs on measured multiple gas rebreathing variables were studied in 14 dogs. The rebreathing method (using He, C18O, and C2H2) allows for measurements of pulmonary capillary blood flow (Qc), diffusing capacity (DLco), lung gas volume, and the combined pulmonary tissue and capillary blood volume (VTPC). VA/Qc imbalance was created by reversibly occluding the right main pulmonary artery or by reversibly obstructing the left main bronchus in eight dogs. Six additional dogs were ventilated with 10 cmH2O positive end-expiratory pressure (PEEP) to create a bimodal distribution of VA/Qc within the lungs. No significant alterations in computed rebreathing variables, except for a small (14%) decrease in DLco, occurred during right main pulmonary artery occlusion, whereas obstruction of the left main bronchus caused parallel decreases (mean of 46%) in all rebreathing variables. Ventilation with 10 cmH2O PEEP for 3 h caused no alterations in VTPC when compared with postmortem determinations of total lung water. Thus marked alterations in distribution of Qc or creation of VA/Qc maldistributions with PEEP caused no significant changes in rebreathing parameters, whereas obstruction of the left main bronchus resulted in decreases in all rebreathing values consistent with the presumed size of the ventilation defect. Thus it appears that rebreathing estimates of VTPC and other rebreathing parameters are accurate in states of moderate VA/Qc maldistribution within the lung.

Airway Obstruction↗
PubMed1984

Retroperitoneal metastatic spread of malignant Brenner tumor.

It became evident that ovarian cancer spreads mainly by continuity to the adjacent pelvic organs. Retroperitoneal node metastases, especially in the absence of other forms of spread, when the neoplasm is confined to the ovary, is less well described. Recent literature stressed that different histological types of ovarian epithelial cancer can and do spread to the retroperitoneal lymphatics early in the course of the disease. In this report we present a patient with FIGO Ia malignant Brenner tumor in whom metastatic disease was found in retroperitoneal lymph nodes. To our knowledge, a similar observation has not been previously described. It should be concluded that selective biopsies of the retroperitoneal lymph nodes should be part of the staging laparotomy for any ovarian carcinoma.

Adult↗
PubMed1984

Interaction of bretylium tosylate with rat cardiac muscarinic receptors. Possible pharmacological relevance to antiarrhythmic action.

The interaction of the antifibrillatory antiarrhythmic drug, bretylium tosylate, with the muscarinic receptor in tissue homogenates from regions of rat brain and heart was investigated. Competition-binding experiments were carried out with the highly specific tritiated antagonist N-methyl-4-piperidyl benzilate. Bretylium tosylate competitively displaced the labeled antagonist from the muscarinic receptor. The binding of the drug to the two brain preparations was found to be best fitted by a one-site model in each case. On the other hand, in the case of both heart preparations, a two-site model yielded a significantly better fit for the binding data than that given by a single-site model. The low affinity-binding constants in the atrium and the ventricle were similar (approximately 10 microM) to those in the brain regions examined, namely, the cortex and the medullapons. Sites with relatively higher affinity for the drug were detected in the heart only, with equilibrium-binding constants of 0.24 +/- 0.12 microM and 0.97 +/- 0.27 microM for the atrium and the ventricle, respectively. The drug also exerted anti-acetylcholine activity (K1 = 14 +/- 2 microM) measured physiologically in the guinea pig atrium, which correlated well with the concentration of the drug observed to be efficacious clinically (approximately 10 microM).

Animals↗
PubMed1984

Sustained release device containing metronidazole for periodontal use.

The purpose of this study was to develop a sustained release device containing metronidazole for insertion within periodontal pockets and to examine the release kinetics in vitro and in vivo. Cast films of ethyl cellulose with or without polyethylene glycol, containing metronidazole, were prepared and exhibited sustained release. Release rate of metronidazole from the film was measured by means of a UV spectrophotometer, and kinetics of release in vitro was found to conform to Higuchi's diffusional model. The microbiological results proved that embedding metronidazole in ethyl cellulose film does not inhibit the biological activity. The release kinetics in vivo correlated with in vitro results, exhibiting a sustained release of metronidazole over a period of three days from 30% metronidazole with polyethylene glycol or 40% metronidazole in ethyl cellulose chloroform cast. This study demonstrates that, by embedding metronidazole in ethyl cellulose, it is possible to obtain sustained release of the drug within the periodontal pocket for three days.

Bacteroides fragilis↗
PubMed1984

Measurement of cardiopulmonary function by rebreathing methodology in piglets.

The use of a multiple gas rebreathing method for the measurement of cardiopulmonary function in mechanically ventilated neonates was evaluated. The following indices of cardiopulmonary function were assessed in 20 piglets (mean weight, 2.3 kg): 1) pulmonary capillary blood flow (Qc), 2) diffusing capacity for carbon monoxide (DLCO), 3) lung gas volume (FRC), 4) oxygen consumption (VO2), and 5) volume of the pulmonary tissues and capillaries (VTPC), the latter an estimate of total lung water. During mechanical ventilation at zero end expiratory pressure, all rebreathing parameters correlated well with body weight. Additionally, a good correlation (r = 0.81, slope = 0.99) between VTPC and postmortem estimate of total lung water was observed. The effect of ventilation with positive end expiratory pressure (PEEP) was then studied in 10 piglets. On increasing PEEP from zero to 15 cm H2O, FRC significantly increased by 208%, Qc significantly decreased by 60%, and no changes in VTPC occurred. Seven piglets were then studied after induction of lung injury by oleic acid infusion. Compared with the pre-oleic acid infusion values, all the rebreathing variables decreased during ventilation without PEEP. Unlike the situation with the normal piglets, when PEEP was increased from zero to 10 cm H2O in the oleic acid-infused piglets, the values for FRC and VTPC significantly increased. Mean VTPC at 10 cm H2O was 20 +/- 2 ml/kg which correlated well (r = 0.93) with the postmortem total lung water value of 19 +/- 1 g/kg. Thus, multiple gas rebreathing methodology is applicable to studies using small animals.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Mesenteric vein thrombosis associated with oral contraceptive administration during pregnancy.

A case is reported of mesenteric venous occlusion in a young woman who by mistake received oral contraceptives during pregnancy. A resection of the damaged small bowel was performed followed by an end to end enteroenterostomy. It is suggested that the hypercoagulable state normally found in pregnancy was aggravated by the hormonal intake and lead to the mesenteric vein thrombosis.

Adult↗
PubMed1984

Rigid membranes of Malayan ovalocytes: a likely genetic barrier against malaria.

A high frequency of nonhemolytic hereditary ovalocytosis in Malayan aborigines is thought to result from reduced susceptibility of affected individuals to malaria. Indeed, Kidson et al. recently showed that ovalocytes from Melanesians in Papua New Guinea are resistant to infection in culture by the malarial parasite Plasmodium falciparum. In order to determine if protection against parasitic invasion in these ovalocytes might be the result of some altered membrane material property in these unusual cells, we measured their membrane and cellular deformability characteristics using an ektacytometer . Ovalocytic red cells were found to be much less deformable in comparison to normal discoid red cells. Similar measurements on isolated membrane preparations revealed a marked reduction in ovalocytic membrane deformability. To produce equal deformation of ovalocytic and normal membranes, ovalocytes required an 8-10-fold increase in applied shear stress, indicating that their membrane was capable of deforming under sufficient stress. To test the possibility that this increased membrane rigidity might confer resistance to parasitic invasion, we performed an in vitro invasion assay using Plasmodium falciparum merozoites and Malayan ovalocytes of varying deformability from seven different donors. The level of infection of the ovalocytes ranged from 1% to 35% of that in control cells, and the extent of inhibition appeared to be closely related to the reduction in membrane deformability. Moreover, we were able to induce similar resistance to parasitic invasion in nonovalocytic normal red cells by increasing their membrane rigidity with graded exposure to a protein crosslinking agent. Our findings suggest that resistance to parasite invasion of Malayan ovalocytes is the result of a genetic mutation that causes increased membrane rigidity.

Blood Viscosity↗
PubMed1983

Brain metastases in early cancer of the uterine cervix. A case report.

This paper describes a case of cancer of the uterine cervix (clinical stage IB) in which signs of brain metastases developed within 1 week of diagnosis. Common sites of distant metastases in patients with carcinoma of the cervix are the liver and lung parenchyma. However, these organs were free of disease and only the brain, an extremely rare site, was involved.

Brain Neoplasms↗
PubMed1983

Second malignant tumors detected by needle aspiration cytology.

Between 1967-1980, 14 second primary cancers were detected by needle aspiration cytology in patients treated for malignant tumors. The interval between the first cancer and the occurrence of the second cancer varied from six months to 21 years. In all 14 cases, the cytologic diagnosis of the second cancer was later confirmed by histopathologic examinations. In 13 patients, the second cancer was dissimilar from the first one, and in one patient the two cancers were subtypes of lymphoproliferative tumors. In three patients the cytologic diagnosis falsely defined the subtype of the second cancer. Malignant lymphoma was the predominant tumor either as the first cancer (50%) or as the second cancer (43%). Thyroid cancer occurred as the second cancer in three patients. Needle aspiration cytology of all newly appearing lesions can be performed routinely during follow-up examinations to discriminate between relapsed disease and new malignant tumors.

Adult↗
PubMed1983

Parathyroid localization by computed tomographic scanning.

Increased accuracy of parathyroid hormone assays has yielded an earlier diagnosis of primary hyperparathyroidism, often in an asymptomatic stage. Non-invasive modalities used to localize parathyroid abnormalities have not been accurate for small adenomas. Although arteriography has been shown to be accurate in detection of adenomas, the invasive nature of the study, as well as possible complications, minimizes its use in preoperative localization of parathyroid abnormalities. The computed tomographic (CT) scan was used preoperatively in eight patients to assess its accuracy in localizing parathyroid abnormalities. The radiographic findings were correlated with surgical and pathologic findings. The conditions of seven patients were correctly diagnosed preoperatively by the CT scan, including that of one patient with diffuse hyperplasia. With the increased accuracy attained by this noninvasive examination, we believe that CT scanning should be a routine part of the preoperative examination of patients with primary hyperparathyroidism.

Adenoma↗
PubMed1983

Nasal polyposis with invasion into the orbit.

Proptosis of the left eye developed in a 51-year-old man with a long history of nasal polyposis. Displacement of the orbit was associated with a palpable mass superior and lateral to the orbit. Roentgenographic studies, including a sinus series, computed tomographic scan, and axial tomogram of the left orbit, showed a soft-tissue mass in the superolateral compartment of the left orbit and left frontal sinus, suggesting a mucocele. The surgical and pathological findings disclosed polyps of the frontal sinus invading the orbit through a dehiscence of the lateral orbital roof. To our knowledge, this is the first reported case of invasion of frontal sinus polyp into the orbit through the superolateral wall.

Adult↗
PubMed1983

Serotonin and the ovarian hyperstimulation syndrome.

Ovarian hyperstimulation syndrome was induced in rabbit by administration of human menopausal gonadotropin (HMG) and human chorionic gonadotropin (HCG). In an attempt to establish whether serotonin plays a part in the induction of this syndrome, the hyperstimulated rabbits were divided into two groups and were administered known anti-serotonin drugs, cyproheptadine and methysergide, respectively. The group treated with cyproheptadine, a non-specific serotonin antagonist, exhibited significant acceleration in the regression of the syndrome. Methysergide, a specific serotonin antagonist, administered to the second group, neither prevented the occurrence of the syndrome nor accelerated its regression. The results of this work indicate that serotonin does not seem to be directly involved in the production of the ovarian hyperstimulation syndrome in rabbits.

Animals↗
PubMed1983

Nonstress Test in standing and lying women.

The effect of the maternal postural position on the Nonstress Test (NST) was evaluated in 14 normal pregnancies at 38-40 weeks of gestation. Each women was studied for two periods of 30 min, each in the standing and left lateral recumbent positions. Comparing both positions no significant difference was found in the number of fetal movements and heart rate accelerations. The total surface area of accelerations (TSAA) was significantly larger in the standing position.

Female↗