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S Abrahams

Publications and source records attributed to S Abrahams.

At least 37 records · Page 2Linked to original sources
PubMed1995

Expression patterns of three genes in the stem of lucerne (Medicago sativa).

We have identified three stem abundantly expressed genes in lucerne (alfalfa, Medicago sativa). A cDNA library, constructed from lucerne stem polyadenylated RNA, was screened by differential hybridization. From this screening, cDNA clones that correspond to genes which are preferentially, or specifically, expressed in the stem were isolated. MsaS1 encodes an unidentified protein, MsaS2 encodes an S-adenosyl-homocysteine hydrolase and MsaS3 encodes an extensin-like protein. Northern blot analysis of RNA isolated from individual stem internodes indicated that the three corresponding genes show differing developmental patterns of expression. The expression of MsaS1 was confined to the youngest stem tissue and may be regulated by sucrose. In stem tissue the level of RNA for the three genes decreased in response to wounding. Tissue print hybridization analysis was used to localize the expression of the genes to the xylem side of vascular bundles in lucerne stems.

Adenosylhomocysteinase↗
PubMed1995

A study of a new osmotic purgative for colonoscopy. Is Golytely worth its salt?

An osmotic laxative containing polyethylene glycol and sodium sulfate (Golytely Braintree Laboratories, Inc., Braintree, MA) is widely used to clean the colon for colonoscopy. However, its salty taste makes the mixture unpalatable. We therefore tested the claim that a similar solution but without sodium sulfate (Golytely-RSS Braintree Laboratories, Inc., Braintree, MA) makes preparation of the colon more acceptable to patients in a double-blinded randomized controlled trial. Colonic preparation using polyethylene glycol with or without sodium sulfate was randomized in 100 patients due to undergo colonoscopy. The overall acceptability of the regimen was measured on a linear analogue scale and an estimate of symptoms was obtained. Body weight and serum electrolytes, urea, creatinine, hemoglobin and hematocrit were determined before and after preparation in order to assess fluid absorption. The efficacy of colonic cleansing was graded by the colonoscopist. Four patients did not complete the protocol, 47 received the regimen containing sodium sulfate and 49 received the regimen without it. The two groups did not differ in age or body mass. There was no statistical difference in the overall acceptability of the two regimens to the patients (median acceptability rating 74 for regimen with sodium sulfate, range 4-100 compared with 77 for regimen without, range 3-100, p = 0.32, Mann-Whitney test). Nor was there any difference in taste, nausea, vomiting, cramping or perianal discomfort or in the endoscopists' rating of the cleanliness of the colon. The serum sodium concentration rose slightly (mean 1.6 mmol/L) when the regimen with sodium sulfate was used.(ABSTRACT TRUNCATED AT 250 WORDS)

Cathartics↗
PubMed1995

A positron emission tomography study of frontal lobe function (verbal fluency) in amyotrophic lateral sclerosis.

Positron emission tomography (PET) was used to investigate the location of cerebral cortical and subcortical abnormalities in non-demented patients with amyotrophic lateral sclerosis (ALS). Involvement of the frontal lobes was investigated with a task of executive frontal lobe function (verbal fluency/word generation), using a PET activation paradigm. Two groups of ALS patients defined by the presence or absence of cognitive impairment were tested. ALS patients who had cognitive impairments showed a region of cortical and subcortical dysfunction which extended across a wide area of the frontal lobes, and included the insular cortex and thalamic nuclear complex. These findings support the notion that extra-motor involvement is relatively common in ALS and broadens concepts of selective vulnerability in ALS.

Amyotrophic Lateral Sclerosis↗
PubMed1995

Recognition memory for words and faces following unilateral temporal lobectomy.

The study tested the ability of the Warrington Recognition Memory Test (1984) to discriminate between patients with left and right temporal lobe lesions. Forty-seven patients who had undergone unilateral temporal lobectomy (TL) (23 right- and 24 left-sided operations) were tested on the two components of the test, recognition memory for words (RMW) and recognition memory for faces (RMF). The results show that the right TL group were significantly worse than the left TL group on RMF. Conversely, the left TL group were significantly worse on the RMW test, confirming earlier results relating to material-specific deficits in long-term memory following TL. The RMF test was relatively sensitive and specific in detecting significant impairments associated with right TL, but the RMW proved much less sensitive to the effects of left TL. RMW and RMF discrepancy scores were found not to discriminate well between the two groups of patients.

Adult↗
PubMed1994

Variability of pulsatile luteinizing hormone secretion in young male volunteers.

Characteristics of spontaneous pulsatile luteinizing hormone secretion were compared in ten young healthy men in three 24-h profiles obtained at intervals of 14 days and 3 months. The ages of the volunteers ranged from 19 to 25 years, and heights and weights were within normal limits. Blood samples were taken at 10-min intervals and plasma luteinizing hormone (LH) was determined in the same immunoradiometric assay using monoclonal antibodies. Conventional pulse detection was carried out with PULSAR and CLUSTER programs. In addition, a simultaneous multiple parameter DECONVOLUTION was applied. As a group, no significant differences between the three profile series were found for any of the calculated parameters of LH concentration or LH secretion. However, most parameters showed low correlation coefficients between the three study periods, suggesting that substantial individual variations might contribute to the more reliable group results. Median coefficients of variation (cv) for the individual subject ranged from 9.7% (interpulse interval and endogenous half-life) to 37.7% (mass per burst). However, the maximal individual cv observed was 78.4%. Intra-individual variability was lower than the variability between subjects for quantitative properties of LH concentration and secretion, although not significantly so for all parameters. In conventional pulse detection, the highest individual reliability was found for mean and integrated LH concentrations (median cv 10.2 and 13.7%, respectively), number of pulses per 24h (CLUSTER, median cv 12.2%), mean pulse amplitude (PULSAR, median cv 10%) and interpulse interval (CLUSTER, median cv 9.7%). In DECONVOLUTION analysis, the endogenous LH half-life (median cv 9.7%), secretory burst amplitude (median cv 14.8%) and interburst interval (median cv 14.5%) revealed the lowest intra-individual variation. In contrast, the half-duration of a secretory episode and the mass of LH secreted per burst proved to be the least reliable measures (median cv 32.7% and 37.7%, respectively). Calculated endogenous LH production rates correlated highly (p < 0.01) across all three sessions. The relative frequencies of the LH peak amplitudes/heights and peak widths (durations) showed almost identical distribution curves for all three sampling periods. In conclusion, a high reproducibility of group results for both integrative parameters and pulse characteristics of LH concentrations and secretion were found in normal men. However, intra-individual reliability was variable and at times considerable, depending on the parameter chosen. These observations suggest caution in the interpretation of single LH profiles from individual subjects or patients unless the variation reported herein is considered.

Adult↗
PubMed1993

The relationship between abnormalities of cognitive function and cerebral activation in amyotrophic lateral sclerosis. A neuropsychological and positron emission tomography study.

Neuropsychological assessment of 16 clinically non-demented patients with amyotrophic lateral sclerosis (ALS) and 16 age-matched controls revealed significantly (P < 0.05) impaired verbal fluency and picture recall in the ALS patients. On the basis of their verbal fluency scores, two subgroups of the ALS patients (five high, five low scores) and a different group of five age-matched controls then underwent positron emission tomographic (PET) measurement of regional cerebral blood flow (rCBF). Scans were performed in the resting state and while subjects performed stereotyped or freely selected movements of a joystick with their right hand. The pattern of cerebral activation associated with self-generated activity was determined by comparing the profile of rCBF during freely selected and stereotyped joystick movements. Statistical parametric mapping was used to determine significant differences in rCBF between the groups at rest and during activation. Regional cerebral blood flow at rest was significantly (P < 0.01) reduced in the anterior cingulate cortex of both ALS subgroups in comparison with controls. The profile of cortical and subcortical activation during performance of freely selected joystick movements relative to stereotyped movements was abnormal in ALS patients: (i) ALS patients with a normal fluency score showed significantly (P < 0.01) attenuated rCBF responses in comparison with controls in the left medial prefrontal cortex (Brodmann area 10) and the right and left parahippocampal gyri; (ii) ALS patients with impaired verbal fluency showed significantly (P < 0.01) attenuated rCBF responses in comparison with controls in the right and left medial prefrontal cortex (areas 9 and 10), the rostral aspects of the right anterior cingulate cortex (areas 24 and 32), the right parahippocampal gyrus and the anterior thalamic nuclear complex; (iii) ALS patients with impaired verbal fluency showed significantly (P < 0.01) attenuated rCBF responses in comparison with patients with normal verbal fluency in the right parahippocampal gyrus, the anterior thalamic nuclear complex and the rostral anterior cingulate cortex (area 24). Regional cerebral blood flow at rest in the right parahippocampal gyrus of ALS patients was significantly correlated with verbal fluency score (P = 0.01) and picture recall score (P = 0.01). Activation of the anterior thalamic nuclear complex in ALS patients was also significantly correlated with verbal fluency score (P = 0.001) and picture recall score (P = 0.01). The results show that abnormalities of function are present in regions along a limbo-thalamo-cortical pathway in some ALS patients during performance of a self-generated motor task.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1991

Contribution of renal medullary mitochondrial density to urinary concentrating ability in mammals.

In mammals, the length of the loops of Henle increases with increasing body size without a concomitant rise in urinary concentrating ability. Because mass-specific metabolic rate falls with increasing body mass, this study sought to determine the extent to which this decline in metabolic rate could explain the low urinary concentrating ability of large mammals with long loops of Henle. Mitochondrial ultrastructural parameters were measured in the medullary thick ascending limbs (mTALs) of a series of nine mammalian genera ranging in body mass from 0.011 kg (bats) to approximately 400 kg (horses). The volume of mitochondria as a percent of mTAL cellular volume declined with increasing body mass (Mb-0.056). Inner mitochondrial membrane area per volume of mitochondrion also declined with increasing body mass (Mb-0.034), as did basolateral membrane area per unit mTAL cellular volume (Mb-0.075). Thus, not only do mitochondria occupy more volume of mTAL cells of smaller mammals, but those mitochondria are also more densely packed with cristae. Inner mitochondrial membrane area per unit volume of mTAL cell cytoplasm scaled as Mb-0.092. The decline in inner mitochondrial membrane area and basolateral membrane area per volume of mTAL cell may explain at least in part the relationship between body mass and renal concentrating ability in mammals of different sizes.

Animals↗
PubMed1990

Effects of respiratory activity on starvation survival of marine vibrios.

The marine bacterium Vibrio fluvialis NCTC11328 responded to nutrient depletion by a reduction in cell volume, and this was prevented by conditions that eliminated respiration as a source of energy. Addition of the protonophore, CCCP, removal of oxygen and introduction of mutations leading to defects of the respiratory chain prevented size reduction during periods of nutrient limitation. Further, survival of the wild-type strain during starvation was reduced under anaerobic conditions and survival of respiratory mutants under aerobic conditions was reduced compared with that of the parent strain. Removal by mutation of the respiratory Na+ pump from Vibrio alginolyticus did not inhibit size reduction or lead to reduced viability in starved cultures.

Aerobiosis↗
PubMed1989

The distribution of MAG in association with the axonal lesions of canine progressive axonopathy.

The distribution of myelin-associated glycoprotein (MAG) was examined by immunocytochemistry in the spinal cord, accessory cuneate nucleus and lumbar ventral nerve roots of dogs affected by progressive axonopathy. These areas were chosen because of the frequency of spheroids and the associated changes in the myelin sheath, including vacuolation, demyelination, remyelination and accumulation of a granular, amorphous material within the sheath. Normal animals demonstrated the expected distribution of MAG; periaxonal and associated with uncompacted membrane such as Schmidt-Lanterman incisures. The majority of early axonal spheroids were surrounded by a MAG-positive zone but in the larger swellings and longer duration cases this was sometimes absent in places even though the axon was associated with Schwann cell processes. Axons in vacuolated fibres were commonly surrounded by a single adaxonal process of Schwann cell and normal periaxonal space. This was immunoreactive for MAG but in situations where the process was incomplete or the space distorted, staining was absent. The granular material failed to stain for MAG. Distorted Schmidt-Lanterman incisures, a feature of the advanced disease, were strongly positive. In the CNS, spheroids without myelin sheaths or unassociated with oligodendroglial processes were negative for periaxonal MAG. The study confirms the localization of MAG at the periaxonal space. It also raises the question of how the distribution of periaxonal MAG is affected by axonal swelling with a consequent increase in axonal surface area.

Animals↗
PubMed1987

Progressive axonopathy: an inherited neuropathy of boxer dogs. 4. Myelin sheath and Schwann cell changes in the nerve roots.

Changes in the myelin sheath have been studied in the nerve roots of dogs with Progressive axonopathy, an autosomal recessive inherited neuropathy. The earliest changes were attenuation of the sheath at the proximal paranode and adjacent internode, probably in response to the axonal swelling which occurs in this area. Myelin bubbles were frequently observed along internodes. As the disease developed, progressively more fibres demonstrated short internodes of irregular length and thin myelin sheaths suggesting extensive remyelination and remodelling of the sheath. Short lengths of axons devoid of myelin, and occasional macrophages were also encountered. Sheaths of both original and newly formed internodes were highly irregular in outline. Occasional intra-axonal projections of adaxonal Schwann cell cytoplasm were observed, but complex interdigitations were unusual. A moderately electron-dense, granular material accumulated within the myelin sheath, becoming more obvious in the advanced disease. This material of unknown origin and composition was located predominantly at the intraperiod line principally between the adaxonal cytoplasm and the inner major dense line, but also at Schmidt-Lanterman incisures and between paranodal loops. Xenografts of the canine nerves into athymic mice failed to demonstrate any of the myelin sheath changes. The temporal and spatial relationship of the myelin sheath and axonal changes and the failure to reproduce the natural lesion in grafts suggest that Schwann cell alterations probably occur in response to the axonal changes.

Animals↗
PubMed1986

Progressive axonopathy: an inherited neuropathy of boxer dogs. 3. The peripheral axon lesion with special reference to the nerve roots.

Progressive axonopathy is an autosomal recessive inherited neuropathy of Boxer dogs with lesions in the CNS and PNS. This paper describes the axonal changes in the lumbar and cervical nerve roots and tibial nerve. By 2 months of age the proximal paranodal areas of many larger diameter fibres show small axonal swellings, sometimes with attenuation or loss of the associated myelin sheath. Axoplasmic changes within swollen and non-swollen fibres include disorganization of the peripheral neurofilaments and small accumulations of vesicles and vesiculo-tubular profiles, particularly in the sub-axolemmal area. Occasional fibres, more often in the cervical roots, are massively distended with disorganized neurofilaments. The frequency of the membranous accumulations decreases with progression of the disease. Many axons show a markedly irregular or corrugated outline and are surrounded by an attenuated sheath. The peripheral axonal cytoskeleton is disorganized and misaligned, whereas the central structures maintain a more normal arrangement. Regenerating axonal clusters are common in the cervical ventral roots but occur infrequently in the lumbar roots. Similar axonal changes occur in the peripheral nerves but at a much lower frequency. Any membranous accumulations or cytoskeletal disorganization are more probable in the proximal tibial nerves, while the frequency of axonal degeneration and regeneration increases distally. The morphological appearances indicate gross disturbances in axon-sheath cell relationships and suggest that abnormalities in the transport of various axoplasmic organelles may be involved in the pathogenesis of the axonal lesion.

Animals↗
PubMed1982

Ultrastructural localization of substance P immunoreactivity in the ventral horn of the rat spinal cord.

At the light microscope level, the minute concentrations of substance P (SP) in rat spinal ventral horn can be visualized best by amplification with the double bridge PAP method of Vacca et al. (1975; 1980) in 5 microns paraffin tissue sections. Morphologically, the immunoreactive sites resemble punctate bodies. They occur in close apposition with the large ventral horn cells and their associated neuronal processes. By the Sternberger PAP procedure, we now describe these punctate bodies at the electron microscope level. Ultrastructurally, they appear as tiny boutons (terminal and preterminal) and small unmyelinated processes. The boutons and processes typically contain one to several immunolabeled dense core vesicles among many immunolabeled clear vesicles. They range in size near the limit of resolution of the light microscope (LM), thereby justifying further the use of LM amplification staining by the double bridge method. The immunolabeled boutons often synapse with large smooth dendrites (which may originate from motoneurons) by asymmetrical or symmetrical synaptic densities. Their synaptic densities appear immunostained as well. The data support the view that the electrophysiological action of SP in the ventral horn occurs in part by synaptic action along the processes of the ventral horn cells. Other mechanisms of action are considered for the peptide as well. Additional types of membrane specializations (synaptoid junctions) and SP neural circuits are described below.

Animals↗
PubMed1976

Anti-donor immune responses in prediction of transplant rejection.

We assessed various immune responses against donor tissue to determine their value in the diagnosis and prediction of clinical rejection episodes. Twenty-six consecutive clinical renal-transplant recipients were examined. Cell-mediated lymphocytotoxicity preceded and accompanied 41 of 45 rejection episodes (P less than 0.001). Complement-dependent antibody was present in 12 of 15 rejections (P less than 0.002)--four not accompanied by, and eight in association with, cell-mediated lymphocytotoxicity. Mixed lymphocyte reactivity or nonreactivity and inhibition by autologous serum occurred equally often in rejection and quiescence. Lymphocyte-dependent antibody occurred during both rejection episodes and quiescent phases, with a greater frequency during quiescence (P = 0.05). Cell-mediated lymphocytotoxicity was the best predictor of rejection (P less than 0.05). Cell-mediated lymphocytotoxicity was the best predictor of rejection (P less than 0.001), and was more easily suppressed by standard immunosuppressive therapy, than complement-dependent antibody. If specific cell-mediated lymphocytotoxicity, with or without antibody, recurred after rejection therapy, the graft underwent further rejection.

Antigen-Antibody Reactions↗
PubMed1976

Transplant monitoring: patterns of the immune response.

Immune responses, specific to the stored donor tissue, were measured in 26 recipients over 4,000 days. CML positive crossmatches were associated with accelerated rejections (three cases). LDA positive crossmatches resulted in primary non-functioning kidneys (three cases). Post-transplantation. CML (16 hour inculation) was associated with rejection (p equals 0.001), highly predictive of rejection (p equals 0.001), and when positive after rejection treatment, was associated with a failure to respond (p equals 0.005 - 0.01). 51Cr-CDA was also associated with rejection (p equals 0.002). Recovery of these immunologic participants from the explanted kidney substantiated that they were important effector mechanisms in vivo.

Antibodies↗
PubMed1975

Lymphocyte-dependent antibody and renal graft rejection.

A patient with preformed cytotoxic lymphocyte-dependent antibody (L.D.A.) against the specific renal transplant donor rapidly rejected the grafted kidney. The characteristics of rejection were not those of hyperacute rejection due to cytotoxic complement-dependent antibody or of acute rejection is attributed to the cytotoxic activity of L.D.A. The avoidance of transplants based on positive crossmatches by the L.D.A. test or at least the carrying out of the L.D.A. crossmatch is advised.

Adult↗