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Biomedical subjects

J Altman

Publications and source records attributed to J Altman.

At least 145 records · Page 8Linked to original sources
PubMed1975

Postnatal development of the cerebellar cortex in the rat. IV. Spatial organization of bipolar cells, parallel fibers and glial palisades.

The ontogeny of the spatial organization of some components of the molecular layer was investigated in cerebella sectioned systematically in the sagittal, coronal and horizontal planes. There is no discernible organization in the distribution of cells of the proliferative zone of the external germinal layer (EGL) but from birth the differentiating bipolar cells of the subproliferative zone are aligned parallel to the surface and to the long axis of the folium. While they are still in or at the base of the EGL, the bipolar cells emit long processes, the future parallel fibers. The next step is the outgrowth of a vertical process which may reach the base of the molecular layer before the granule cell nucleus becomes translocated. The idea that the cell body truly migrates through the molecular layer is not supported by the observations. Bergmann glia cells are frequently seen in Golgi material in neonates but they are probably less numerous than in older infants and their processes are not as well aligned. It is only gradually that the EGL is perforated by flial endfeet which in older infants are occasionally organized into longitudinal rows. In mature cerebella the parallel fibers are separated by thin and relatively narrow, unstained spaces which are oriented in the longitudinal plane and can be traced from the pial surface to a zone just above the layer of Purkinje cells. It is postulated that these spaces are occupied by glial palisades formed by apposed thin vertical processes to which many Bergmann glia cells contribute. The alignment of these palisades is dependent on the orientation of parallel fibers. When the parallel fibers are reoriented by X-irradiation the glial palisades become correspondingly realigned. These observation indicate that the oriented growth of parallel fibers, which follows the polarization of bipolar cells, determines the spatial organization of the glial framework of the molecular layer. They also suggest that the glial palisades mediate functions that are not primarily developmental in nature.

Animals↗
PubMed1975

Radiation-induced interference with postnatal hippocampal cytogenesis in rats and its long-term effects on the acquisition of neurons and glia.

The long term consequences of graduated interference with the acquisition of hippocampal neurons and glia during early infancy were examined with quantitative histology and 3H-thymidine autoradiography. the head region containing the hippocampus was irradiated from day two on with either two (2X), four (4X), six (6X) or eight (8X) doses of 150-200r X-rays. The animals were killed at 30, 60, 90 and 120 days of age. The morphology of the hippocampus was normal in all irradiated groups with the characteristic interlocking flods of the pyramidal and granular layers. While the number of pyramidal calls of Ammon's horn was unaffected, the number of granule cells of the dentate gyrus was progressively and permanently reduced from control levels by the different dosage schedules (2X, 59% reduction; 4X, 77%; 6X, 83%; 8X, 84%). Incidental observations in control animals indicated a 20% increase in granule cells between 30 and 120 days of age in agreement with earlier observations of granule cell labelling after 3H-thymidine injections in adult rats. The time of origin of tha approximately 15-16% of the granule cells surviving irradiation in the 8X group was determined by injecting either pregnant females (gestation days 19-20) or pups (days 0 and 1) with two successive dosed of 3H-thymidine; the animals were irradiated from day two on the eight X-ray doses. The granule cells surviving in the postnatally injected group were all unlabelled and comparable in number to the unlabelled cells in control animals that were given five successive postnatal injections of 3H-thymidine. This established that the radioresistant complement of granule cells is formed prenatally. In the prenatally injected group, over half the surviving cells were labelled; it was assumed that those not labelled were formed befor gestation day 19. In contrast to the permanent reduction in the number of granule cells, there was some reestablishment of the number of cells in the dentate molecular layer and the Ammonic stratum oriens; in the fimbria, recovery in cell number was complete by 60 days. In a supplementary autoradiographic experiment, cell proliferation in the granular layer and in the fimbria was determined at 60 days of age after a single postnatal injection of 3H-thymidine on either day 15 or day 20 in the control, 2X, 4X and 6X groups. The number of labelled cells in the irradiated groups was always well below control levels in the granular layer, but it was wither above or at the same level as controls in the fimbria. Tentative interpretations were offered for the differential long-term effects of variable X-ray schedules on the neuronal and glial populationf of the hippocampus.

Animals↗
PubMed1975

Postnatal development of locomotion in the laboratory rat.

In laboratory rats (Rattus norvegicus) aged 1 to 21 days emergence of postural and locomotor skills was studied in the open field and in experimental situations with homing used as motivation. Righting is mediated initially by curving and rocking of the trunk, later head and shoulder are rotated, and lastly the hindlimbs turn and provide co-ordinated support. Pivoting prodominates during the second half of the first week, crawling during most of the second week, and walking or running by the end of the second week. Balancing on narrow paths and compensating for lateral displacement on rotating rods mature later, as do various skills (climbing up or down on inclined surfaces, rods and ropes, and jumping across gaps) that require substantial hindlimb co-ordiantion.

Animals↗
PubMed1975

7-N-amidinocephalosporins.

7-Aminocephalosporanic acid tert-butyl ester reacts quantitatively at--20 degrees with iminium chlorides to give amidino derivatives. Removal of the tert-butyl protecting group with trifluoroacetic acid and treatment with 1 equiv of triethylamine yield the corresponding zwitterions. These compounds were less active than their penicillin analogs.

Amidines↗
PubMed1975

Pseudo-malignant lesions in Paget's disease of bone.

Two patients with unusual features of Paget's disease are reported. In one patient a circumferential focal and periosteally based mass of Paget's disease presented as a mass lesion superimposed on the sclerotic phase of Paget's disease in the distal femur. Biopsy of the mass showed Paget's disease without neoplasia. The mass has remained unchanged roentgenographically in a 2 year period. In a second patient, a lesion occurred in the mid-portion of the tibia and showed features of the early and radiolucent phase of Paget's disease. In a 4 year period, the lesion has progressed to a more sclerotic phase and to occupy the proximal end of the tibia as well as its mid and lower portions.

Aged↗
PubMed1975

Survey of malpractice claims in dermatology.

A statistical survey of malpractice claims asserted against dermatologists was made. The subject matter of the claims was divided into eight major categories: (1) drug reactions, (2) x-ray burns, (3) poor cosmetic result following surgery, (4) poor cosmetic result following medication, (5) failure to diagnose cancer, (6) improper diagnosis, (7) infection from treatment, and (8) miscellaneous. The study showed that a group of "serious" damage cases, which accounted for 34% of total claims, generated 94% of total dollar losses. The problem areas for malpractice claims appeared to be drug reactions, cosmetic chemosurgery, and failure to diagnose cancer.

Dermatology↗