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Biomedical subjects

S Segal

Publications and source records attributed to S Segal.

At least 397 records · Page 22Linked to original sources
PubMed1982

Mechanisms controlling differentiation and function of antigen-presenting macrophages.

We have briefly reviewed our studies on the mechanisms controlling the differentiation and activation of peritoneal antigen-presenting cells. We demonstrated that the peritoneal population is composed of two main subsets of cells, only one of which participates actively in primary antigen presentation. The latter is missing in athymic mice and seems to differentiate under the influence of the shortlived, cortisone-resistant subpopulation of thymocytes. The maturation of the peritoneal macrophages is subjected also to an additional inducing effect, that of the spleen. Macrophages from splenectomized donors are impaired both with respect to antigen presentation to naive and to primed lymphocytes, and with respect to phagocytosis of "opsonized" bacteria. The mature antigen-presenting cell is subjected to activating signals deriving from the Fc-bound Ig molecule. This is mediated via a tetrapeptide, tuftsin, which is cleaved off the CH2 portion of the Ig and activates the immunogenic effect of the antigen-pulsed macrophage.

Animals↗
PubMed1982

The effect of phentolamine on synaptosomal phosphatidylinositol in experimental galactose toxicity.

Abnormal myo-[2-3H]inositol incorporation into phosphatidylinositol has been found in phentolamine-treated synaptosomes that were isolated from the cerebral hemispheres of galactose toxic rats and incubated with [33P]Pi and myo-[2-3H] inositol. In galactose toxic rats phentolamine-stimulated myo-[2-3H]inositol labeling of phosphatidylinositol was 70% greater than in normal animals. This enhanced labeling of synaptosomal phosphatidylinositol in galactose toxic rats during stimulation with phentolamine is in marked contrast to the depressed myo-inositol labeling of phosphatidylinositol reported with acetylcholine stimulation.

Animals↗
PubMed1982

Glutamine uptake by rat renal basolateral membrane vesicles.

The presence of a sodium-dependent, saturable uptake process is described in basolateral membranes of rat renal cortex for L-glutamine. Concentration-dependence studies indicate the presence of multiple transport systems with Km1 of 0.032 mM and V1 of 0.028 nmol/mg of protein per min, and Km2 of 17.6 mM and V2 of 17.6 nmol/mg of protein per min. Lysine completely inhibits the high-affinity, low-capacity Km system and partially inhibits the low-affinity, high-capacity system. Cystine and other dibasic amino acids also affect glutamine uptake.

Amino Acids↗
PubMed1982

Limitations of jet ventilation through the laryngoscope.

A series is presented of 100 patients who underwent direct laryngoscopy under general anaesthesia. Our preferred technique of ventilation is jet insufflation by an injector attached to the blade of the laryngoscope, as it provides the surgeon with a quiet and completely exposed larynx. In nine cases, chest expansion was assessed as inadequate by the anaesthetist. These patients were obese with a short neck, and/or stiff-necked; thus, insertion of the laryngoscope was difficult and a good seal between it and the larynx could not be achieved. Arterial blood gas values in six of these patients demonstrated marked hypoventilation. To improve ventilation in these patients an alternative technique of insufflation through a nasotracheal catheter was used. Arterial blood gas values indicated that this method resolved the problem of hypoventilation. Although the catheter somewhat limits the view of the endolarynx, the improved ventilation outweighs the drawbacks of this technique. It is suggested that for the obese and/or stiff-necked patient, a nasotracheal catheter be used electively for ventilation.

Adolescent↗
PubMed1982

Homocystine uptake in isolated rat renal cortical tubules.

Isolated rat renal cortical tubules were used to study the nature of homocystine entry into the tubule cell and its transport interactions with cystine and the dibasic amino acids. The uptake of homocystine with time was progressive, reaching a steady state after 60 min. of incubation. Analysis of the intracellular pool after 5 and 30 min. of incubation revealed that virtually all of the transported homocystine had been converted to other metabolites of the transsulfuration pathway. The major metabolite was cystathionine with a somewhat lesser, but still significant amount as S-adenosylhomocysteine. A kinetic analysis showed that two systems for cellular entry of homocysteine existed with a Km1 of 0.17 mM and a Km2 of 7.65 mM. Arginine and lysine inhibited homocystine uptake via the low Km, high affinity system, but appeared not to inhibit the high Km, low affinity system. Cystine inhibited the low Km, high affinity system, but had an indeterminate effect on the high Km, low affinity system. Homocystine inhibited the uptake of cystine, lysine and arginine by isolated rat renal cortical tubules. The inhibition of homocystine on cystine uptake appeared to occur on both the high and low Km system for tubule cell entry of cystine. The data suggest that the low Km system for homocystine transport is shared with cystine and the dibasic amino acids. These data extend the knowledge of homocystine metabolism and provide a rational basis for new approaches to the treatment of homocystinuria.

Amino Acids↗
PubMed1982

The in vitro synthesis and secretion of alkaline phosphatase from first trimester human decidua.

We studied the in vitro synthesis and secretion of alkaline phosphatase by human first trimester decidual tissue incubated in organ culture. Decidua synthesizes two different alkaline phosphatase isoenzymes; heat stable and heat labile. decidual tissue maintains a constant pool of alkaline phosphatases. The synthesis of alkaline phosphatase may be the driving force for its secretion. The de novo synthesis and secretion rate of alkaline phosphatases were also investigated. The higher specific radioactivities of the secreted enzymes than those found in the tissue may suggest that newly synthesized alkaline phosphatase is preferentially released. The intracellular distribution of the alkaline phosphatase isoenzymes was compared as well. The characteristics of the two isoenzymes are different in human decidua of maternal origin from those previously reported in the human placenta originating from embryonic stem cells.

Alkaline Phosphatase↗
PubMed1982

Early repair of traumatic perforations of the tympanic membrane in children.

The results of early repair of traumatic perforations of the tympanic membrane by alignment and approximation of the fragmented drum and paper patching of the defect are described in 14 children. The procedure was performed under light general anaesthesia, using Ketalar (ketamine hydrochloride) in a minimal dosage. In all cases except one, healing following patching was complete and uneventful. The disadvantage of general anaesthesia is outweighed by the prompt and uncomplicated healing, and a higher percentage of defect closure, compared with untreated cases in other reports.

Audiometry, Pure-Tone↗
PubMed1982

Effect of splenectomy on the progression of postoperative pulmonary metastases of the 3LL tumor.

Surgical excision of the local intrafootpad tumor of the 3LL lung carcinoma is followed by accelerated growth of its lung metastases. When, however, splenectomy was performed concomitantly with tumor excision, the acceleration of lung metastases was prevented. In cases where excision of the local tumor took place when it reached large sizes, concomitant splenectomy did not prevent the accelerated growth of the lung metastases. If, however, at these stages of tumor growth splenectomy was performed 3 days prior to the excision of the tumor, it did prevent the accelerated growth of metastases. Intrafootpad reinoculation of tumor cells following tumor excision and splenectomy caused further reduction in metastatic growth. The results suggest that existence of two possible distinct mechanisms which control metastatic growth: the local tumor might exert non-immunologically, an inhibitory effect on its lung metastases, and the spleen, possibly via suppressor lymphocytes, may suppress an immune effector activity against the tumor metastases, an activity which is manifested following splenectomy.

Animals↗
PubMed1982

In vitro sperm cervical mucus penetration: studies in human and bovine cervical mucus.

The objective of this study was to assess the feasibility of substituting bovine estrus cervical mucus (BCM) for human midcycle cervical mucus (MCM) for investigation of sperm cervical mucus (CM) interaction and evaluation of cervical factor in infertility. In vitro sperm cervical mucus penetration tests (ICMPT) were performed with the use of ejaculated human spermatozoa collected from fertile donors and infertile men. Tests were performed in a flat capillary tube with the use of MCM and BCM. Mean +/- standard deviation (SD) of sperm penetration in MCM was 32.3 +/- 15.5 mm and in BCM 27.3 +/- 12.1 mm after 90 minutes of migration. The difference was significant (P less than 0.001). A highly significant correlation was found between sperm penetration in MCM and BCM. The depth of sperm penetration in both human cervical mucus (HCM) and BCM was also significantly related to sperm count and motility. Positive correlation was observed between normal morphologic features and sperm migration in BCM but not in MCM. It is concluded that human sperm penetrate BCM at a slower rate than MCM, but BCM can be effectively substituted for HCM in laboratory testing of sperm penetration.

Animals↗