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Biomedical subjects

M Goldberg

Publications and source records attributed to M Goldberg.

At least 613 records · Page 34Linked to original sources
PubMed1982

[Multidisciplinary approach in public health research. The example of accidents and safety at work].

This article critically analyses the various scientific approaches taken to industrial accidents, particularly in epidemiology, ergonomie and sociology, by attempting to outline the epistemological limitations in each respective field. An occupational accident is by its very nature not only a physical injury but also an economic, social and legal phenomenon, which more so than illness, enables us to examine the problems posed by the need for a multidisciplinary approach in Public Health research.

Accidents, Occupational↗
PubMed1981

Structure and properties of 5-deazaflavin radicals as compared to natural flavosemiquinones.

In order to gain more insight into flavin radicals, on which the selection of 1e-, and 2e- -oxireduction modes in flavoproteins depends, we have investigated structure, spectral properties and decay mode of molecular species occurring in the half-reduced 5-deazaflavin "model" system by flash photolysis and pulse radiolysis. (1) Enforced 1e- -reduction of 5-deazaflavin yields the short-lived red-colored 1-HdFl, which is a strong reductant. In the absence of any electron acceptor, this radical decays by 1,5-prototropy (see below) and dismutation, which is rapidly reversed upon illumination. Competing with this photo-comproportionation, irreversible formation of the photo-stable sigma-dimmer (HdFl)2, covalently linked via C(5), is observed, which becomes prevalent under prolonged illumination. (2) Enforced 1e- -abstraction from 1,5-dihydro-5-deazaflavin yields the tautomeric 5-HdFl, which is a mild oxidant and is transparent at lambda 480 nm. Prototropy 5-HdFl in equilibrium or formed from 1-HdFl can be rate-determining in 5-deazaflavin redox reactions. Hence, the radical state in the 5-deazaflavin system does not mediate double 1e- -oxidoreduction as do natural flavosemiquinones. Instead, 5-deazaflavin flavors nucleophilic substrate addition (carbanion transfer) and formation of intermediate sigma-adducts in (photo)reductions even over the extent observed with natural flavin. This confirms the description of 5-deazaflavin as a "flavin-shaped nicotinamide derivative". It explains at the same time the mechanism of 5-deazaflavin acting as a mild and yet potent photosensitizer in 1e- -reductions of biological redox systems. (3) It is shown that replacement of N(5) by CH in the flavin nucleus also leads to the disappearance of the known action-pK in the photoreduction, which confirms the assignment of the latter pK in the natural flavin system to 5-protonation of the excited flavin triplet. From these model studies the following biological conclusions can be confirmed: The tautomer equilibrium of natural flavin semiquinones is diffusion-controlled and regulated thermodynamically: 5-HFl in equilibrium or formed from 1-HFl, while in flavo-proteins the same equilibrium is regulated by regiospecific H-bridges from the apoprotein, which thus decides between 1e- - (stable 5-HFl) and 2e- -reaction (unstable 1-HFl) modes.

Electron Transport↗
PubMed1981

Vascular problems associated with carotid body tumors.

In the last 25 years at the University of Toronto, 27 patients with carotid body tumors were encountered. All patient problems appeared to be related to delay in treatment, size of the tumor, and previous operations. To minimize hazard in this procedure, one should avoid operating on elderly and unfit patients, and otherwise operate early to avoid the problem of a bulky tumor, using a simple subadventitial approach while reserving complete carotid excision and vascular replacement for complicated adherent lesions. Preoperative angiography is mandatory for definitive diagnosis, which permits proper planning of available operating room time, blood replacement, and availability of workers with expertise in vascular surgery. Adequate surgery is effective in tumor clearance, preventing malignant transformation and the lethal effects of local growth.

Adult↗
PubMed1981

Hyponatremia.

Explore the source record for details and available documents.

Addison Disease↗
PubMed1981

Novel studies on a "silent" high affinity mutant hemoglobin (San Diego, beta 109 Val replaced by Met).

A patient with a "silent" mutant hemoglobin characterized by high oxygen affinity and erythrocytosis is described. A novel approach was used to identify the mutant chain. Functionally active alpha and beta chains were prepared from hemolysates of the patient and a normal control. Hybrid tetramers of patient's beta chain were prepared. Functional studies revealed that the patient's beta chains had a higher oxygen affinity (P50, 1.1 torr) than normal beta chains (P50, 1.7 torr) and the hybrid containing the patient's beta chains had a P50 similar to the patient's "stripped" hemolysate. It was assumed therefore that the mutation was in the beta chain; structural studies using cyanogen bromide cleavage revealed that the patient had Hb San Diego, beta 109 Val replaced by Met, and that the patient's cells contained approximately 50 percent mutant hemoglobin.

Aged↗
PubMed1981

Experience with subclavian vein for vascular access.

We report our experience with the subclavian vein as a route for temporary vascular access. By modifying the technique described by Uldall one can place these catheters at the bedside without the need of a separate exit tunnel. They are easily maintained in place and allow for early discharge home while awaiting permanent vascular access maturation. The results of approximately 600 dialysis treatments showed adequate clearence with a mean postdialysis drop in creatinine of 5.0mg./dl. and BUN of 46mg./dl. Complication rates were minimal with no hemo or pneumothorax. The rate of complications between bedside and operating room placement was not different. We feel the low complication rate, the ease of insertion, and the patency at home makes this an attractive alternative to other means of temporary dialysis such as: peritoneal dialysis, repeat femoral vein catheterization or arteriovenous shunts.

Catheterization↗
PubMed1981

Dexamethasone for prevention of respiratory distress syndrome: multiple perinatal factors.

Antepartum dexamethasone administration was associated with a significant lowering of the incidence of respiratory distress syndrome (RDS) and with marked reduction of early neonatal mortality in premature infants. Dexamethasone had its greatest effect in infants delivered between 28 and 32 weeks' gestation (P < .001), and the difference was still significant up to 34 weeks' gestation (P < .05). Although the effect of dexamethasone was more marked in patients with intact membranes, it was also effective in those with prolonged rupture of the membranes. Membrane condition before delivery was unrelated to the incidence of RDS. The effectiveness of dexamethasone was analyzed with respect to the condition of the infant at delivery, the mode of delivery, and multiple births. As compared to the controls, dexamethasone was most effective in singletons, infants delivered vaginally, and those with high Apgar scores. The effect of dexamethasone was not significant in twins, breech deliveries, cesarean section deliveries, or infants with low Apgar scores. The effects of dexamethasone appear to be modified by intrauterine asphyxia. Dexamethasone therapy cannot be substituted for optimal delivery conditions of the premature.

Dexamethasone↗
PubMed1981

[Freeze fracturing and thin-section study of intercellular junctions between odontoblasts and the rat incisor. Changes induced by vinblastine].

The study of thin sections and replicas obtained after freeze-fracture showed that the intercellular junctions of the young secretory odontoblasts of the rat incisor were of two types. Zonula adherens (desmosomes) united the cellular bodies at the predentinal border. Ahead of these structures gap junctions were observed. An injection of vinblastine sulfate induced 4h, a) an enlargement of intermembranous spaces between the gap junctions, b) a reduction of the contact surfaces in the desmosomes and c) a thickening of the intracytoplasmic dense material made of microfilaments, associated with the junctional complex. These modifications favoured the observation of these structures after freeze-fracture. The desmosome junctions could play a mechanical function (partitioning of the predentinal compartment) whereas the gap junction allowed the electrotonic coupling of the odontoblasts. They allowed however an intercellular diffusion route for ionic components (calcium) and matrix components of serum origin.

Animals↗
PubMed1981

Microchannels in the surface zone of artificially produced caries-like enamel lesions.

In the surfaces zones of artificial carious lesions, tiny microchannels, about 0.5 - 1.5 micrometers in diameter and roughly 100 micrometers in length, have been observed. The mineral components seem to be concentrated at the lumen borders, whereas the organic components have disappeared or are disorganized. These observations suggest that the channels mentioned are involved in the lesion development and play an important role in diffusion (transport) processes taking place between the sub-surface lesion and the liquid phase outside the lesion. The microchannels originate in prisms in the perikymata of the surface enamel. They extend in the direction of the Hunter-Schreger bands, mainly in connection with diazones. No relationship could be found between the microchannels and the direction of the prism sheaths. This indicates that in initial artificial lesion formation the enamel structure plays an important role.

Dental Caries↗
PubMed1981

Effects of methylprednisolone and azathioprine on bronchial healing following lung autotransplantation.

The effect of low-dose immunosuppressive therapy upon the healing of the bronchial anastomosis and skin wound following lung autotransplantation was evaluated. Autotransplantation was performed in two groups of dogs: Group 1 (15 dogs) received no immunosuppression and Group 2 (13 dogs) received postoperative immunosuppression with methylprednisolone (2 mg/kg) and azathioprine (1.5 mg/kg). Two to four skin incisions 7 cm in length were made in the dorsal region of each dog. Dogs were put to death at 4, 9, 16, and 23 days postoperatively and the bronchial anastomoses and skin wounds were evaluated by breaking strength measurements. Bronchus and skin breaking strength increased with time in both groups. Bronchus breaking strength was similar in the two groups at day 4 and day 9. However, by day 23 bronchus breaking strength was significantly higher in Group 1 (p less than 0.001). Skin breaking strength was significantly higher in Group 1 on days 9 and 16 (p less than 0.005) and on day 23 (p less than 0.001). Our results suggest that low-dose methylprednisolone and azathioprine significantly affect the breaking strength of both bronchial anastomoses and healing skin incisions following canine lung autotransplantation.

Animals↗
PubMed1981

Recurrent thrombotic thrombocytopenic purpura after viral infection. Clinical and histologic simulation of chronic glomerulonephritis.

We describe a patient with recurrent thrombotic thrombocytopenic purpura (TTP) manifested solely by aphasia after influenza infection. The clinical diagnosis was not made during acute episodes, and during the intercurrent period the patient had features of chronic glomerular disease, including hypertension, proteinuria, RBC casts, and a nonspecific renal histological appearance. A final episode of aphasia, acute renal failure, and microangiopathic anemia and thrombocytopenia made the diagnosis of TTP apparent. Chronic glomerular disease may in rare instances be a manifestation of occult TTP or the sequel of a prior acute episode of this disorder.

Acute Kidney Injury↗