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Biomedical subjects

M Goldberg

Publications and source records attributed to M Goldberg.

At least 487 records · Page 27Linked to original sources
PubMed1986

Ultrastructural location of complex carbohydrates in developing rat incisor enamel.

The ultrastructural distribution of complex carbohydrates in an early formation stage of rat incisor enamel was investigated by staining with the periodic acid-thiocarbohydrazide-silver proteinate reaction (PA-TCH-SP) for vicinal glycol-containing glycoconjugates, the phosphotungstic acid-chromic acid mixture (PTA) for glycoproteins, and the cationic dyes alcian blue or bismuth nitrate for sulfated glycoconjugates. In order to remove selectively sulfated complex carbohydrates, half of the serial sections obtained were digested with a bovine testicular hyaluronidase prior to staining. Far fewer electron-dense deposits were observed with the PA-TCH-SP method on hyaluronidase-treated sections, especially those subsequently treated for 48 hours with TCH. On the other hand, the minimal staining obtained with PTA was much more intense on sections treated with hyaluronidase where linear fiberlike structures were observed. With cationic dyes, staining of dotlike alignment structures and ground substance was obtained but was completely abolished by hyaluronidase treatment. Cuprolinic blue in a critical electrolyte concentration, ruthenium hexamine trichloride used with aldehyde during fixation, as well as rapid-freezing followed by freeze-substitution validate that this dotlike distribution is not an artefact of processing. The staining results demonstrated that the glycoproteins and sulfated complex carbohydrates in developing rat incisor enamel each display a specific distribution pattern. The glycoproteins were present as fiberlike structures and the sulfated carbohydrates appeared as dotlike formations located close to the surface of the fiberlike structures, and/or in the spaces between them.

Animals↗
PubMed1986

Visualization of proteoglycans and membrane-associated components in rat incisor predentine and dentine using ruthenium hexammine trichloride.

Ruthenium hexammine trichloride (RHT) used as a probe to visualize anion groups in the predentine and dentine of rat incisors, showed a complex distribution pattern including: intercellular proteoglycans (Pg), detected in the predentine as granules 10-15 nm in diameter and as filaments. Non-aggregating Pg was observed in the spaces between collagen fibres as an amorphous group substance. The dentine included smaller RHT-positive granules, observed after thin-section demineralization; pericellular aggregates, 30-50 nm in diameter, which were absent at the onset of the cell coat along the plasma-membrane of the odontoblast process and of the membrane itself. All these RHT-positive components might be Pg and/or sialoglyconjugates and glyco- or phospholipids present on the plasma membrane.

Animals↗
PubMed1986

Guanabenz: a centrally acting, natriuretic antihypertensive drug.

Guanabenz is acutely natriuretic and diuretic in saline expanded animals. In man, guanabenz has not resulted in sodium retention as seen with other comparable antihypertensives. To directly define the action of guanabenz on sodium and water excretion in man, we performed clearance studies during water diuresis on eight hypertensive subjects under metabolic balance conditions. Each subject underwent three studies: 1) baseline study: no drug, a water diuresis study; this was followed by a saline load (= 2% BW); 2) acute study (24 hr after baseline): 16 mg guanabenz PO; and 3) chronic study: after one week of guanabenz 8 mg PO BID. In the acute guanabenz studies there were: 1) no changes in GFR or ERPF; 2) an increase in both sodium excretion and fractional sodium excretion; 3) a rise in free H2O clearance (CH2O) and (CH2O/GFR) X 100%. These findings were not sustained in the chronic guanabenz studies. We conclude that in man (preconditioned with prior saline loading) guanabenz is acutely natriuretic and water diuretic. These effects are due to decreased tubular sodium and water reabsorption, probably related to inhibition of alpha adrenergic activity. The data are consistent with selectively reduced renal sympathetic activity affecting sodium transport and provide a basis for the absence of edema and sodium retention associated with guanabenz therapy.

Adult↗
PubMed1986

Brain abscess: a complication of oesophageal dilatations.

A 16-month-old boy underwent oesophageal dilatations following an unsuccessful attempt to locally resect a 3 cm long lye stricture. He then developed a brain abscess which was surgically drained. Subsequently, a right colon interposition was performed to bypass the stricture. Following oesophageal dilatations, bacteraemia and fever are common but the occurrence of metastatic brain abscesses is rare. This serious complication should be kept in mind when long-term treatment by repeated oesophageal dilatations is planned.

Brain Abscess↗
PubMed1986

Associations between several sites of cancer and nine organic dusts: results from an hypothesis-generating case-control study in Montreal, 1979-1983.

A multi-cancer site, multi-factor case-control study was undertaken to generate hypotheses about possible occupational carcinogens. Probing interviews were carried out with over 2,000 subjects. All incident cases of 19 sites of cancer in males aged 35-70 and resident in Montreal were eligible. The interview was designed to obtain detailed lifetime job histories, and information on potential confounders. Each job history was reviewed by a team of chemists who translated it into a history of occupational exposures. These occupational exposures were then analyzed as potential risk factors in relation to the sites of cancer included. For each site of cancer analyzed as a case series, controls were selected from among the other cancer sites in the study. This report concerns the associations between sites of cancer for which there were over 100 cases processed (stomach; colorectal, also analyzed by subsites; lung; prostate; bladder; kidney; non-Hodgkin's lymphoma) and nine organic dusts (wood; paper; grain; flour; fabrics; cotton; wool; synthetics; fur). All site-exposure combinations were investigated. The ones that provided the most interesting leads were lung-wood dust (odds ratio (OR) = 1.5), stomach-wood dust (OR = 1.5), colorectal-synthetic fiber (OR = 1.5), bladder-synthetic fiber (OR = 1.8), non-Hodgkin's lymphoma-cotton dust (OR = 1.9), colon-grain dust (OR = 2.6), prostate-grain dust (OR = 2.2), and prostate-paper dust (OR = 2.0). Only the associations with wood dust, synthetic fibers and cotton dust showed some evidence of "dose-response" with duration of exposure. Because it is such a common exposure and appears to increase lung and stomach cancer risks, wood dust may be responsible for a great deal of occupational cancer.

Adult↗
PubMed1986

Granular cell tumor of the pancreas.

We report a rare granular cell tumor of the pancreas. We take this to be the second report of such a tumor in this location, and the first to be diagnosed before death. Endoscopy, angiography, and finally laparotomy were critical in establishing the diagnosis.

Female↗
PubMed1986

Effects of serotonin on the internal anal sphincter: in vivo manometric study in rats.

The effects of serotonin (5-hydroxytryptamine, 5-HT) on the internal anal sphincter were studied in anaesthesized rats. Serotonin induced a dose dependent relaxation of the internal anal sphincter. Methysergide blocked this relaxation, but did not affect the rectoanal reflex. Methysergide did not antagonise the actions of cholinergic and adrenergic agonists on the internal anal sphincter. Other 5-HT antagonists such as cyproheptadine, ketanserin, chlorpromazine, amitriptyline and ergotamine failed to reduce or block the internal anal sphincter relaxation due to 5-HT, nor did they alter the rectoanal reflex. Adrenergic and cholinergic antagonists had no effect on the 5-HT-induced relaxation of the internal anal sphincter, suggesting that 5-HT acts upon the internal anal sphincter via a non-adrenergic, non-cholinergic mechanism. Tetrodotoxin reduced or blocked the relaxation of the internal anal sphincter produced by 5-HT, implying that 5-HT acts through neural pathways rather than directly on the muscle. It is concluded that although 5-HT relaxes the internal anal sphincter, it does not participate in the rectoanal reflex.

Anal Canal↗
PubMed1986

Hypercalciuria of mineralocorticoid escape: clearance and micropuncture studies in the rat.

Chronic mineralocorticoid excess results in the predicted retention of salt and water followed by a period of escape from sodium retention and hypercalciuria. We studied a rat model during mineralocorticoid escape (ME) with clearance and micropuncture studies to ascertain the nephron site and possible role of parathyroid hormone. Rats during ME were hypercalciuric compared with a matched saline group. Clearance studies revealed a marked difference in the calcium-to-sodium fractional excretion ratio (FECa/FENa) between saline-expanded and mineralocorticoid (desoxycorticosterone acetate, DOCA)-escaped animals (saline-expanded, 0.40 +/- 0.09 vs. DOCA, 1.02 +/- 0.14; P less than 0.01). The addition of either hydrochlorothiazide (HCTZ) or amiloride (AMIL) to the ME animals significantly lowered this ratio from that seen in the intact ME group (DOCA-HCTZ, 0.47 +/- 0.07; DOCA-AMIL, 0.83 +/- 0.14). Neither parathyroidectomy (PTX) nor parathyroid hormone infusions (PTH) in ME animals altered the FECa/FENa from that seen in the intact ME group (DOCA-PTX, 1.15 +/- 0.20; DOCA-PTH, 1.25 +/- 0.18). Segmental micropuncture along the length of superficial nephrons demonstrated no differences in calcium delivery to late proximal, early distal, and late distal sites. However, FECa was markedly increased in ME animals compared with saline controls (saline, 0.48 +/- 0.13% vs. DOCA, 1.62 +/- 0.24%; P less than 0.05). We conclude that the hypercalciuria of ME is independent of PTH and can be significantly reduced by HCTZ or AMIL. Micropuncture and clearance data suggest that the hypercalciuria of ME is mediated in the terminal nephron. The differences in the results when superimposing various factors that influence distal nephron calcium reabsorption on ME may be related to differences in their site(s) of activity on calcium transport.

Amiloride↗