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Biomedical subjects

J Diamond

Publications and source records attributed to J Diamond.

At least 163 records · Page 9Linked to original sources
PubMed1985

Environmental management of senile dementia.

A model is described of social activity in club settings geared to the needs of demented and cognitively impaired old people living in the community. As well as reality orientation, guided social interaction, physical activity, dance therapy and craftsmanship, important elements include transport, home assessment and follow-up visits. Parallel support groups for spouses are essential to the complete program, which coordinates planning with local authority agencies. The complex also includes educational programs for staff, professionals and the public. This design is seen as an on-going neighborhood project in which at focal points of the week, the patient enters a meaningful social environment with which he can cope.

Aged↗
PubMed1985

The palatal arch.

Explore the source record for details and available documents.

Facial Bones↗
PubMed1985

Pertussis vaccine and whooping cough as risk factors in acute neurological illness and death in young children.

The National Childhood Encephalopathy Study received reports on 1182 cases of serious acute neurological illnesses in children admitted to hospital in Britain. The frequency of risk factors in cases was compared with matched controls. A personal or family history of convulsions was found significantly more often in cases than in controls, but no such excess was found for a history of allergy. Case children were significantly more likely to have received diphtheria, tetanus and pertussis (DTP) vaccine within seven days before onset and to have a history of whooping cough during the month of onset. The risk of serious acute brain conditions after the disease was more than six times that of three doses of DTP. In addition, there is evidence that deaths attributed to whooping cough may seriously underestimate the number associated with pertussis infection.

Brain Diseases↗
PubMed1984

Temporal and spatial constraints on the collateral sprouting of low-threshold mechanosensory nerves in the skin of rats.

We have studied the collateral sprouting of intact low-threshold mechanosensory nerves into adjacent denervated skin in rats. An "isolated" field was produced by extensive denervations of the surrounding skin; sprouting of the remaining cutaneous nerve supplying the field was looked for in the form of field expansion into the surrounding denervated territory at various postoperative intervals. Such isolated fields failed to expand in the adult rat for periods up to at least 85 days. "Nonfunctional" sprouting is unlikely to explain this failure. However, similar experiments done in very young animals gave a different result. In rat pups aged less than 20 days, isolated fields did expand, but this ceased at about 20 days, and attempts to evoke it after this time were unsuccessful. There seems to be a critical period for sprouting of these touch-sensitive nerves into denervated skin, and our evidence suggests that it may not begin until about 15 days of age. Within this developmental window the sprouting that occurs is spatially constrained, an isolated field expanding preferentially into denervated skin of the parent dermatome; if only skin of neighboring dermatomes is available there is no expansion. In contrast, low-threshold nerves regenerated readily after a crush at all ages studied, and the mechanosensory fields established by regenerating nerves expanded progressively into denervated skin without apparent constraints at dermatomal boundaries. The temporal and spatial constraints found for the sprouting of intact low-threshold axons are in marked contrast to their absence for the well-described sprouting of high-threshold (nociceptive) nerves.

Age Factors↗
PubMed1984

Lectin-binding properties of the Merkel cell and other root sheath cells in perinatal rat vibrissae.

Surface carbohydrates on the Merkel cell of the outer root sheath (ORS) were investigated in 1- to 4-day-old rat vibrissae by use of rhodamine isothiocyanate (RITC)-conjugated lectins. The red fluorescence of RITC provided a convenient assay for lectin binding to the Merkel cell, which is itself identified by its green fluorescence following selective uptake of the dye quinacrine. In monolayers or suspensions of freshly dissociated ORS cells, the Merkel cell showed high affinity for the alpha-fucose-specific lectin, Ulex europeus agglutinin I (UEA-I), thus revealing a novel feature for a basally located cell. Other high-affinity lectins included concanavalin A (Con A), wheat germ agglutinin (WGA), soybean agglutinin (SBA), and Ricinus communis agglutinin I (RCA-I). In contrast, Dolichos biflorus (DBA), Bandeiraea simplicifolia I and II (BS-I and BS-II), and peanut agglutinin (PNA) virtually excluded the Merkel cell, though PNA-binding sites were unmasked after neuraminidase treatment. Other dispersed ORS cells had varying lectin affinities, and generally binding was inhibited by a competing haptenic sugar. The pattern of lectin binding seen in cryostat and paraffin sections of the vibrissa suggested that the Merkel cells share surface properties with their neighboring basal and/or spinous cells; however, unshared properties are likely to exist since ingrowing mechanosensory nerves recognize the Merkel cells, and not other epidermal cells, as their targets.

Animals↗
PubMed1984

Alkalemia in diabetic ketoacidosis.

A patient with a history of diabetes mellitus and congestive heart failure was taking furosemide and metolazone as diuretics. Diabetic ketoacidosis developed, and the patient became lethargic and confused. Initial biochemical determinations showed an alkalemic pH, serum and urine ketones with an anion gap, and hyperventilation. The hyperventilation was appropriate for the degree of ketoacidosis but it was grossly inappropriate for the alkalemia. This could be explained by a direct effect of ketones on the respiratory center or a sudden increase in hydrogen ion concentration superimposed on previously chronic alkalemic pH due to the potent combination of furosemide and metolazone.

Aged↗
PubMed1984

A fluorescent microscopic study of the development of rat touch domes and their Merkel cells.

The ability of the fluorescent dye quinacrine to label epidermal Merkel cells was used to study the development of touch domes (Haarscheiben) in rat skin. In embryonic and early postnatal pups, sites of touch dome primordia were reliably located within strips of separated trunk epidermis by the occurrence of discrete clusters of fluorescent cells scattered across the basal cell layer. As in excised adult domes, most of these fluorescent (Merkel) cells lay caudal to the emerging tylotrich hair follicle and the cell cluster formed an annular or crescentric disc. Though all the touch domes that comprise the adult population appear to contain labelled Merkel cells by postnatal day 4, the number of these cells per dome continues to increase some 3-4 fold after birth to reach the average adult number (ca 90 cells) on the dorsal trunk around the fifth week. At about this time the adult size (ca 250 micron) of the dorsal Haarscheiben is also reached, as estimated by the length of the long axis of the fluorescent disc. The rostro-caudal orientation of this long axis varied from dome to dome, usually in the range 0-45 degrees clockwise or counterclockwise, and a functional correlate of this is suggested. The density of labelled dome primordia is higher on the dorsal than on the ventral trunk from as early as embryonic day E20-21 and remains higher although the density of domes decreases steadily across the skin during postnatal growth of the animal. This study utilizes a novel fluorescent labelling technique that is applicable to microscopic studies on the development of Merkel cells within their epithelial locations, in this instance the rat touch domes. Although the full population of domes is established early in development, the Merkel cells within a dome continue to increase in number for several weeks after physiological function is known to appear in this structure.

Animals↗
PubMed1984

A quantitative study of the time course of the reduction in Merkel cell number within denervated rat touch domes.

By using the fluorescent dye quinacrine as a marker for the Merkel cells in rat touch domes we have shown that denervation results in a progressive reduction in the number of these cells to a level that remains relatively constant at about 40% of that present at the time of denervation. The time-course of quinacrine fluorescent cell changes after denervation could be described by assuming that (i) there are two populations of quinacrine fluorescent cells, one labile and the other stable, and (ii) the labile population is the one most sensitive to denervation and disappears exponentially with a half-time of ca 10 days. It appeared that this time-course of decay of the labile quinacrine fluorescent cells was the same whether the denervation was performed during the period of postnatal development studied (at 7 and 14 days), when normally Merkel cells are rapidly added to the dome, or later (at 35 and 60 days) when the adult population is virtually established. Correlative electron microscopic studies confirmed that quinacrine fluorescent cell counts reflect fairly accurately the Merkel cell population in denervated domes. These quantitative findings based on the use of quinacrine to visualize the entire Merkel cell population of touch domes show that the normal development and maintenance of these cells are trophically dependent on sensory nerves, although a subpopulation may persist even in long-term denervated domes. In addition, the similarity of the first order rate constant for the decay of quinacrine fluorescent cells after denervation and for the normal generation of quinacrine fluorescent cells suggests that the labile Merkel cell population is one that turns over continuously in the normally innervated touch dome.

Aging↗
PubMed1984

Reinnervation of the rat touch dome restores the Merkel cell population reduced after denervation.

By using the fluorescent dye quinacrine as a marker for the Merkel cells in the rat touch dome, we previously showed that a sustained denervation of the dome causes a rapid and persistent loss of about 60% of its Merkel cells [Nurse, Macintyre and Diamond (1984) Neuroscience 11, 521-533]. We now show that if the sensory nerves to the skin are crushed (or cut) in 2-week old pups and allowed to regenerate, the Merkel cell population within touch domes shows a biphasic response; there is an initial loss of Merkel cells associated with the early phase of denervation, followed by an increase, associated with the phase of reinnervation. Physiological tests revealed that many (though not all) domes within initially deafferented skin had become functionally reinnervated and had their Merkel cell numbers either wholly or partially restored some 40-100 days post operatively. In one case an adult reinnervated dome, that appeared normal physiologically and by its complement of quinacrine fluorescent (Merkel) cells, also had normal histological features in toluidine blue sections and normally innervated Merkel cells in the electron microscope. These results, based on the use of quinacrine to visualize the Merkel cell population in the touch dome, suggest that sensory nerves may induce the differentiation of new Merkel cells in domes where these cells have become reduced after denervation.

Animals↗
PubMed1984

Impulse activity evokes precocious sprouting of nociceptive nerves into denervated skin.

We have studied the sprouting of intact high-threshold mechanosensory nerves into adjacent denervated trunk skin in adult rats behaviorally, histologically, and electrophysiologically. In the anesthetized animal, stimulation of high-threshold endings in back skin by localized pinching elicits a bilateral reflex excitation of the underlying skeletal muscle, the cutaneous trunci muscle (CTM), visible as a twitch-like puckering of the skin. The reflex was also evoked by electrical excitation of A delta and of C fibers in the dorsal cutaneous nerves (DCNs), with characteristic latencies of 7-20 msec and 40-60 msec, respectively; excitation of low-threshold (A alpha) fibers was ineffective. After cutting selected DCNs, the deprived skin became insensible, but pinch responsiveness gradually recovered over the following 2 weeks. Regeneration of cut axons was not responsible for this recovery; when neighboring intact DCNs were cut, however, all responses were abolished in the recovered skin that had been initially denervated. By 3-5 days after denervation, axons in the dermis were all histologically absent or degenerating; when pinch sensitivity was restored to such skin, silver-stainable axons reappeared in the formerly empty Schwann tubes. During the work we noticed that the periodic examination by pinching, used to follow the time course of recovery of function in individual animals, led to an earlier development of this recovery than in animals that were examined only once at a specified time after denervation. This apparent acceleration in the redevelopment of pinch sensitivity was correlated with the appearance of axons in the recovered skin, and was shown to be due to the impulse activity evoked in the remaining nerves by the periodic pinching; it did not occur when the nerves were blocked by tetrodotoxin (TTX), and it was mimicked by a brief (10-min) period of electrical excitation of the A delta fibers in a remaining nerve carried out at the time when the denervation of skin was done. The time course of the phenomenon suggested that the principal effect of the impulses was to shorten the latency to the onset of sprouting in the activated A delta axons; that is, they induced precocious sprouting. The impulses needed to be conducted centrally for the effect to occur, and precocious sprouting failed to occur if the impulses were allowed to proceed only distally toward the skin. It seems that a brief conditioning burst of impulses in A delta axons sensitizes the neurons to the influence of a sprouting stimulus that appears when skin is denervated.(ABSTRACT TRUNCATED AT 400 WORDS)

Afferent Pathways↗
PubMed1984

Effects of isoproterenol and forskolin on tension, cyclic AMP levels, and cyclic AMP dependent protein kinase activity in bovine coronary artery.

The effects of isoproterenol and forskolin on tension, cyclic AMP levels, and cyclic AMP dependent protein kinase activity were compared in helical strips of bovine coronary artery. Elevation of cyclic AMP and activation of the protein kinase appeared to be well correlated with relaxation of potassium-contracted arteries by isoproterenol. Forskolin, at 1 microM or higher concentrations, also markedly elevated cyclic AMP levels, activated the kinase, and relaxed the arteries. However, a lower concentration of forskolin (0.1 microM) caused significant increases in both cyclic AMP levels and cyclic AMP dependent protein kinase activity, but did not relax the muscles. Relaxation caused by isoproterenol was accompanied by an apparent translocation of cyclic AMP dependent protein kinase activity from the soluble to the particulate fraction in these preparations. A similar shift in the distribution of the kinase was caused by various concentrations of forskolin, irrespective of whether the arteries were relaxed or not. In contrast to previous results in other tissues, low concentrations of forskolin (less than or equal to 1 microM), which themselves markedly elevated cyclic AMP levels in the arteries, did not potentiate the effects of isoproterenol on cyclic AMP levels or tension in these preparations. These results suggest that either cyclic AMP is not solely responsible for the relaxation caused by these agents, or some form of functional compartmentalization of cyclic AMP and cyclic AMP dependent protein kinase exists in this tissue.

Animals↗
PubMed1983

Failure of intact cutaneous mechanosensory axons to sprout functional collaterals in skin of adult rabbits.

The original evidence that spared cutaneous nerves will sprout following partial denervation of skin was obtained in adult rabbits, in which nociceptive function returned to the deprived areas. Recently we reported that in the adult rat intact touch-sensitive (low-threshold mechanosensory) nerves fail to establish new functional endings in adjacent denervated skin. We have now investigated low-threshold mechanosensory nerves in the skin of adult rabbits after partially denervating the ear or hind limb; the sprouting of new functional endings into neighboring skin would be revealed by an expansion of the low-threshold receptive fields of cutaneous nerves (the areas of skin from which impulses could be evoked by stroking with a bristle). The results show that intact low-threshold mechanosensory nerves do not establish functional endings in adjacent denervated skin in the adult rabbit. These findings, together with those now reported for the cat as well as the rat, support the conclusion that possibly in all adult mammals intact low- and high-threshold nerves differ in their ability to respond to the presence of adjacent denervated skin by sprouting.

Animals↗
PubMed1983

Merkel cell distribution in the epidermis as determined by quinacrine fluorescence.

The Merkel cell distribution in the basal epidermis of amphibian and mammalian skin was visualized in whole mounts by means of quinacrine fluorescence. In most cases only the isolated epidermis was viewed following dermal-epidermal separation. Tadpole tentacles contained numerous quinacrine fluorescent cells (QFC) 25-40 microns apart. Groups of 2-4 QFC were found around the gland openings in frog epidermis but not in salamander epidermis where the QFC were irregularly scattered 40-100 microns apart. In the rat, ring-like clusters of a few to 200 or more QFC were distributed across the basal epidermis of trunk skin (at touch domes or Haarscheiben), eyelid, ear, nose, and whisker pad. The ridged (glabrous) skin of the nose and footpad contained numerous QFC that appeared to follow the contours of the epidermal ridges. The isolated external root sheath of rat vibrissae contained an upper cylindrical cuff of several hundred QFC; enzymatic dissociation of these sheaths produced individually isolated as well as small clusters of fluorescent and non-fluorescent cells. Electron-microscopic examination of several of these cells confirmed that the fluorescent ones are Merkel cells, identified by the presence of characteristic dense-cored granules; in contrast, the non-fluorescent cells lack this ultrastructural feature.

Ambystoma↗
PubMed1983

Radiation therapy technology manpower needs 1982.

A shortage of radiation therapy technologists has existed in the United States for many years. This report analyzes the data from the third manpower survey of ACR/ASTR carried out in 1981 to 1982, using the Patterns of Care master facility list. Of 1106 questionnaires mailed, 77% were returned. The survey identified 3757 technologists performing radiation therapy technology duties. Of these, 2537 of these were Registered Technologists (Therapy) American Registry of Radiologic Technologists RTT (ARRT), 1220 were not. There has been a good growth in the total number of RTT (ARRT) members as indicated by the 1982 ARRT Annual Report (1148 in May, 1977, 2878 in May, 1982). Using the "Blue Book" Criteria of 1981 of 2 RTT/megavoltage unit or 2 RTT/300 new patients, the technology need (2900) would appear filled. However, 860 of the RTT were performing supervisory or dosimetry duties and 42% of the 2897 staff technologists were non RTT personnel. At the time of the survey, 597 funded vacancies existed (241 in 1977). A trend toward a changing standard of 3 RTT/megavoltage unit, reflecting the increased complexity of modern radiation therapy techniques, especially in Patterns of Care Strata A1, A2, C1 institutions was identified. While great progress has been made, there is a continuing need for recruitment into the 113 existing educational programs to try to stabilize the supply of technologists. Attention should also be given to measures for upgrading the skills and knowledge of the non RTT personnel in the field and retention of the RTT personnel.

Health Facilities↗