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Biomedical subjects

M Grossman

Publications and source records attributed to M Grossman.

At least 145 records · Page 8Linked to original sources
PubMed1993

Adenovirus-mediated transfer of the CFTR gene to lung of nonhuman primates: toxicity study.

In preparation for human trials of gene therapy for cystic fibrosis (CF), we performed a preclinical study of gene transfer into the lungs of baboons. Recombinant adenovirus vectors containing expression cassettes for human cystic fibrosis transmembrane conductance regulator (CFTR) and Escherichia coli beta-galactosidase (lacZ) were instilled through a bronchoscope into limited regions of lung in 14 baboons. A detailed accounting of the extent, distribution, and duration of gene expression is contained in a companion article (Engelhardt et al., 1993b). In this article, we report the results of toxicity studies in which clinical laboratory tests, chest radiographs, and necropsy studies were used to detect adverse effects. The only adverse effect noted was a mononuclear cell inflammatory response within the alveolar compartment of animals receiving doses of virus that were required to induce detectable gene expression. Minimal inflammation was seen at 10(7) and 10(8) pfu/ml, but at 10(9) and more prominently at 10(10) pfu/ml, a perivascular lymphocytic and histiocytic infiltrate was seen. The intensity of inflammation increased between 4 and 21 days. At its greatest intensity, there was diffuse alveolar wall damage with intra-alveolar edema. Airways were relatively spared, despite the intensity of alveolar inflammation. Clinical tests did not accurately reflect the presence of lung inflammation, with the exception of chest radiographs which revealed alveolar infiltrates, but only in regions of lung having the greatest intensity inflammation. We conclude that adenovirus-mediated gene transfer into the lungs of baboons is associated with development of alveolar inflammation at high doses of virus.

Adenoviridae↗
PubMed1993

Effects of radiation therapy on adult brain behavior: evidence for a rebound phenomenon in a phase 1 trial.

Although radiotherapy (XRT) is a necessary course of treatment to prolong life expectancy in patients with many types of brain neoplasms, it has damaging effects that are little understood. We used a comprehensive neuropsychological battery to evaluate five patients with low-grade brain tumors prior to XRT and then at 3-month intervals up to 9 months postcompletion of XRT. We matched patients by age and education with six normal control subjects to assess baseline impairment. In intrasubject comparisons, we examined change over time postcompletion of XRT. In spite of varying locations of tumors, all patients showed deterioration in long-term memory at a mean of 1.5 months postcompletion of XRT. Patients also consistently demonstrated a rebound effect between means of 4.7 and 7.6 months post-XRT. We found no changes over time in working memory, attention, visuospatial processes, or on any other neuropsychological test with the exception of information-processing speed, which quickened over time. Functional measures of fatigue and mood did not correlate significantly with the long-term memory scores. Long-term memory appears sensitive to the proposed white matter changes thought to be the mechanism for the early-delayed effects of XRT. Our findings suggest a neurobehavioral model for studying the effects of XRT on brain functioning.

Adult↗
PubMed1993

Multiphasic allometry.

A multiphasic linear model is presented that describes the allometric relation between body components and permits a smooth transition from one linear segment to the next. Three applications of a diphasic linear model to allometric growth problems were used to illustrate the model. The data sets were selected because a breakpoint exists in the allometric relation. Relations between growth of the alimentary tract and of empty body weight in rabbits, growth of length and of body weight in larval-carp and growth of protein and of fat in pullets were described by a diphasic allometric model. For rabbits and larval-carp, relations were described significantly better by a diphasic instead of a monophasic (simple) allometric model. For situations where response is expected to consist of more than one linear segment, the multiphasic model is recommended.

Animals↗
PubMed1993

A novel approach for introducing hepatocytes into the portal circulation.

Many attempts have been made to treat metabolic diseases of the liver. One approach, called ex vivo gene therapy, is based on correcting the genetic defect in the patient's hepatocytes. In this model, the liver is resected and hepatocytes are isolated, plated in culture, and genetically corrected with recombinant retroviruses. The cells are then harvested and infused into the portal circulation, where they seed in the sinusoids of the liver. In this study, a canine model was used to develop an approach to ex vivo gene therapy that requires only one surgical procedure. The basic concept is to place a catheter in the mesenteric circulation at the time of liver resection that can be used subsequently to deliver hepatocytes into the liver. With four 18 to 28 kg mongrel dogs, a laparotomy was performed, the left lateral segment of the liver was resected, and a 9.5 Fr Hickman catheter was introduced into the inferior mesenteric vein. At 10 days, the catheter was studied angiographically and removed. The catheter remained patent and was easily removed without untoward effects. A subsequent necropsy was performed to evaluate the consequences of this procedure. There was no hematoma at the site of the catheter placement or evidence for intraportal clot. This approach has been used in subsequent studies to treat a patient with familial hypercholesterolemia.

Animals↗
PubMed1992

A novel mechanism for achieving transgene persistence in vivo after somatic gene transfer into hepatocytes.

Infusion of hepatocyte-specific DNA-protein complexes into rats leads to transient recombinant gene expression in liver. The eventual deterioration of gene expression is due in part to instability of the targeted DNA. In a previous report, we noted retention of transgene sequences in liver and persistent recombinant gene expression when the animals were subjected to partial hepatectomy following in vivo gene transfer. In an attempt to define the mechanism(s) responsible for persistent gene expression following partial hepatectomy, we characterized the molecular state of the retained, liver-associated transgenes. Southern blot analysis of DNA from liver tissues harvested various times after in vivo gene transfer and partial hepatectomy (10 min to 11 weeks) demonstrated high levels of transgene DNA (100-10,000 copies/cell). The predominant form of this DNA appeared to be episomal based on analyses of uncut DNA or DNA restricted by an endonuclease with one site in the plasmid. Livers from several animals contained a small proportion of transgene sequences of unknown structure. The existence of episomal DNA in liver was confirmed in experiments in which intact plasmid was rescued from total hepatocyte DNA by transformation of bacteria. Both strands of DNA in the liver-associated plasmid retained a bacterial pattern of methylation suggesting that the plasmid had not replicated in the eukaryotic cell. These results are consistent with the hypothesis that the majority of transgene sequences are retained as stabilized plasmids. The specific form of DNA which is transcriptionally active was not identified in these studies. This represents a new mechanism for retaining foreign DNA in eukaryotic cells in vivo and has implications both for the development of somatic gene therapies and the pathogenesis of viral diseases.

Animals↗
PubMed1992

Hepatocyte-directed gene transfer in vivo leads to transient improvement of hypercholesterolemia in low density lipoprotein receptor-deficient rabbits.

Familial hypercholesterolemia is an inherited disease in humans, caused by a deficiency of low density lipoprotein (LDL) receptors, that we have used as a model for developing liver-directed gene therapies. Our strategy is to reconstitute hepatic LDL receptor expression in vivo by administering a DNA-protein complex that is capable of targeting the delivery of functional LDL receptor genes to hepatocytes. Infusion of this DNA-protein complex into the peripheral circulation of a rabbit animal model for familial hypercholesterolemia resulted in hepatocyte-specific gene transfer and a temporary amelioration of hypercholesterolemia. This noninvasive approach to gene therapy should have applications in the treatment of a wide spectrum of human diseases.

Animals↗
PubMed1992

Sentence comprehension in Parkinson's disease: the role of attention and memory.

Sentence comprehension is a complex process involving at least attentional, memory, grammatical, and semantic components. We report three experiments designed to evaluate the impairments underlying sentence comprehension difficulties in nondemented patients with Parkinson's disease (PD). In the first experiment, we asked patients to answer simple questions about sentences which varied in terms of grammatical complexity and semantic constraint. We found that PD patients are significantly compromised in their ability to perform this task. Their difficulties became more prominent as grammatical complexity increased, but they were significantly assisted by semantic constraints that limited possible interpretations of a sentence. Analyses of individual patient profiles revealed heterogeneous performance across the group of PD patients and somewhat inconsistent performance for patients across testing sessions. In the second experiment, we tested the possibility that patients' heterogeneous performance on the sentence comprehension task is due to an impairment in memory or attention, cognitive domains known to be compromised in some PD patients. Although PD patients and control subjects differed on one memory measure, there were no significant correlations between attention and memory performance and the results of the sentence comprehension task. In the final experiment, we manipulated the sentences used in the first experiment in a fashion that stressed the need for memory and attention in a sentence. The results indicated that PD patients are significantly compromised in their ability to attend to certain critical grammatical features of a sentence. A regression analysis identified specific grammatical, semantic, and attentional mechanisms as significant contributors to PD patients' overall sentence comprehension, accounting for over 97% of the variance in their performance. We conclude that there are multiple sources of cognitive difficulty underlying PD patients' sentence comprehension impairment.

Aged↗
PubMed1992

Ex vivo gene therapy of familial hypercholesterolemia.

Familial hypercholesterolemia (FH) is an autosomal dominant disorder caused by a deficiency in the receptor that clears low density lipoprotein (LDL) from the serum (reviewed in Ref. 1 and 2). Patients with one abnormal LDL receptor allele have moderate elevations in plasma LDL and suffer premature coronary artery disease (CAD). Approximately 5% of all patients under 45 who have had a myocardial infarction carry this trait. Patients with two abnormal LDL receptor genes (homozygous deficient patients) have severe hypercholesterolemia and life-threatening coronary artery disease in childhood. Strategies for treating patients with FH are directed at lowering the plasma level of LDL. In heterozygotes, this is accomplished through the administration of drugs that stimulate the expression of LDL receptor from the normal allele (2). This therapeutic approach is not effective in the treatment of homozygous deficient patients, especially those that retain less than 2% of residual LDL receptor activity. Partial amelioration of hyperlipidemia has been achieved in some homozygous deficient patients by diverting the portal circulation through a portacaval anastomosis (3) and by chronic plasmapheresis therapy (4). A more direct approach has been to correct the deficiency of hepatic LDL receptor by transplanting a liver that expresses normal levels of LDL receptor. Three patients that survived this procedure normalized their serum LDL-cholesterol (5-9). We have used an authentic animal model for FH, the Watanabe Heritable Hyperlipidemic rabbit (WHHL), to develop gene therapies for the homozygous form of FH (10-13). The WHHL rabbit has a mutation in its LDL receptor gene which renders the receptor completely dysfunctional (12) leading to severe hypercholesterolemia, diffuse atherosclerosis, and premature death. The potential efficacy of gene therapy for FH is supported by a series of studies we have performed in the WHHL rabbit in which we have achieved metabolic improvement (14-18). Liver tissue was removed from WHHL rabbits and used to isolate hepatocytes and establish primary cultures. A functional rabbit LDL receptor gene was transduced into a high proportion of hepatocytes using recombinant retroviruses, and the genetically corrected cells were transplanted into the animal from which they were derived. Transplantation of the genetically corrected, autologous hepatocytes was associated with a 30-40% decrease in serum cholesterol that persisted for the duration of the experiment (4 months, Ref. 18). Recombinant derived LDL receptor RNA was detected in liver for at least 6 months. There was no apparent immunological response to the recombinant derived LDL receptor.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Transplantation of genetically modified autologous hepatocytes into nonhuman primates: feasibility and short-term toxicity.

Ex vivo gene therapy directed to the liver is being developed for the treatment of inherited metabolic diseases. Transplantation of hepatocytes that have been transduced with a low-density lipoprotein (LDL) receptor gene is a potential form of therapy for familial hypercholesterolemia (FH). We have demonstrated efficacy of ex vivo gene therapy for familial hypercholesterolemia in a rabbit animal model of this disease. In preparation for human trials, we describe in this report experiments in baboons for documentation of the feasibility and safety of autologous hepatocyte transplantation. Three baboons underwent a partial hepatectomy and their hepatocytes were isolated, cultured, and transduced with a retrovirus containing the human LDL receptor gene. The hepatocytes were harvested and infused into an indwelling catheter that had been placed into the inferior mesenteric vein at the time of liver resection. The baboons tolerated the procedures well and are being maintained and clinically evaluated for an indefinite time period. Follow-up evaluations have ranged from 3 to 8 months. Clinical evaluations have been unremarkable and blood chemistry and hematology determinations have stayed within normal limits.

Animals↗
PubMed1992

Somatic gene transfer in the development of an animal model for primary hyperparathyroidism.

The overproduction of hormones is associated with a variety of endocrinological disorders. We have used somatic cell gene transfer of human PTH (hPTH) to develop an animal model of hypercalcemia and osteoclastic skeletal resorption. Recombinant retroviruses were used to transduce a functional hPTH gene into cultured rat fibroblasts. The recombinant-derived preproparathyroid hormone peptide was appropriately processed in this ectopic cell, and intact hPTH (1-84) was secreted at a high level (2-5 ng/10(6) cells/24 h). Transplantation of the PTH-secreting cells into syngeneic rat recipients was associated with the development of hypercalcemia mediated by increasing serum concentrations of hPTH. Thyroparathyroidectomy in these hypercalcemic rats producing hPTH did not result in hypocalcemia and tetany, which was observed in control animals undergoing thyroparathyroidectomy. Chronic overproduction of hPTH (60 days) was associated with severe hypercalcemia, metastatic calcification, and histological changes of osteoclastic resorption of bone. This animal model will be useful in studying the pathophysiology of severe hyperparathyroidism in humans and should help in the evaluation of new medical therapies for hypercalcemia.

3T3 Cells↗
PubMed1992

Estimation of genetic parameters for somatic cell score in Holsteins.

Genetic parameters of somatic cell scores for Holstein cows were estimated using an animal model and REML for two data sets. Set 1, with 13,017 records from 5278 cows, was used to obtain variance components, heritability, and repeatability for two lactation measures: the simple average and the weighted average of test day data. Set 2, with 14,418 records from 4806 cows, was used to obtain genetic correlations for the simple average between lactations 1 and 2, between lactations 1 and 3, and between lactations 2 and 3. Simple and weighted average of test day somatic cell scores had the same heritabilities (.12) and repeatabilities (.35). Phenotypic variances were about 1.2, and herd-sire interaction variances were small (.002). Genetic correlation for somatic cell score was about .55 between lactations 1 and 2 and between lactations 1 and 3 and .65 between lactations 2 and 3. Phenotypic correlation was .20 between lactations 1 and 2, .16 between lactations 1 and 3, and .31 between lactations 2 and 3.

Animals↗
PubMed1992

Characterization of poultry egg production using a multiphasic approach.

Egg production for an individual hen is described by a multiphasic model in which each phase is determined by number of eggs within a clutch, including internally laid eggs, and pause between clutches. Number of eggs in a clutch is determined by circadian rhythm, which consists of a daily rhythm and lag. Internal laying is a result of asynchrony in the development of the oviduct and the ovary. Pause consists of a circadian rhythm and a period called delay. It is expected that lag and internal laying are determined genetically, whereas delay is determined by the environment, especially by photoperiod. A multiphasic model was developed to characterize egg production by lag and delay, expressing cumulative egg number in terms of time. Data need to be adjusted for internal laying prior to the analysis. The inverse function, expressing time in terms of cumulative egg number, was used to estimate average lag and delay for individual hens. Hourly data from four hens over a 16-day period were analyzed to estimate parameters for lag and delay. Data were preadjusted for internal laying and for pause. Lag ranged from -.08 to 2.11 h, and was related positively to number of clutches and, consequently, related negatively to average length of clutch and total number of eggs over the period. Average delay was about 16 h, which may be determined by the light:dark ratio.

Animals↗