Search PubMed⌕ Search

Biomedical subjects

R J Desnick

Publications and source records attributed to R J Desnick.

At least 307 records · Page 17Linked to original sources
PubMed1980

Immunologic aspects of enzyme replacement therapy. An evaluation of the immune response to unentrapped, erythrocyte- and liposome-entrapped enzyme in C3H/HeJ Gush mice.

The ability of autologous erythrocytes and liposomes to provide nonimmunogenic vesicles which protect entrapped enzyme from immunologic surveillance and initiation of an immune response was assessed in C3H/HeJ Gush mice following repeated administration of these vesicles with and without entrapped enzyme. Erythrocyte-entrapped bovine beta-glucuronidase elicited no antibody response detectable by double diffusion, passive hemagglutination, complement-dependent lysis, or time-course experiments. Moreover, erythrocyte entrapment protected the enzyme from circulating antibody in mice previously sensitized with unentrapped enzyme. In contrast, repeated IV injection of negatively-charged liposomes loaded with enzyme induced both humoral and cellular responses. Low levels of antibody to the bovine enzyme were detectable by the double antibody technique; no antibodies to the liposome were detectable by complement lysis. In time-course experiments, significant decreases in tissue recoveries of liposome-entrapped beta-glucuronidase were observed in mice sensitized with enzyme-loaded liposomes compared to the recoveries in unsensitized mice, due in part to the rapid degradation of antigen-antibody complexes. A similarly decreased tissue recovery of liposome-entrapped enzyme was apparent in mice with circulating anti-beta-glucuronidase antibody, indicating the inability of liposomes to protect entrapped protein from immunologic surveillance. The cellular response to the liposome vesicle was characterized by the enhanced phagocytic activity of reticuloendothelial cells in the liver and spleen, and the activation of peritoneal macrophages. These results identify erythrocytes as nonimmunogenic carriers capable of protecting entrapped protein from immunologic surveillance and therefore suitable for enzyme replacement endeavors. However, the demonstration that both buffer- and enzyme-loaded liposomes induce an immune response mandates further investigation of these carriers prior to clinical trials of liposome-entrapped therapeutic agents.

Animals↗
PubMed1980

Enzyme therapy XIV. Comparison of methods for enzyme entrapment in human erythrocytes.

Seven methods of erythrocyte entrapment--six by hypotonic exchange loading and one by chlorpromazine-induced endocytosis--were evaluted for (1) efficiency of incorporation of beta-glucuronidase, inulin, and glucose; (2) presence of beta-glucuronidase on the erythrocyte surface, as detected by hemagglutination or complement-dependent lysis in the prsence of antibody to beta-glucuronidase; (3) in vitro leakage of entrapped markers; and (4) morphologic alterations by scanning electron microscopy. Dependent on the method of entrapment, the incorporation of markers ranged from 0.7% to 6.2% for beta-glucuronidase, 3.4% to 31% for inulin, and 1.2% to 12.2% for glucose. Maximal incorporation by hypotonic exchange loading occurred when the initial concentration of sodium chloride (150 mM) was reduced to 50 or 75 mM. However, beta-glucuronidase was detected on the erythrocyte surface by hemagglutination for these methods as well as a dialysis method of loading. Essentially no leakage of entrapped enzyme was detected (< 1%) for all methods, although up to 11% of entrapped glucose was released during a 3 hr incubation at 37 degrees C in buffered whole blood. Finally, entrapment methods requiring the greatest reduction in salt concentration resulted in the formation of echinocytes, whereas stomatocytes were observed after entrapment by methods requiring lesser salt dilutions. These results demonstrate the efficiency of entrapment and relative integrity of erythrocytes following various loadng procedures and suggest that in vitro assessment may provide a useful predictor of the imunogenicity and in vivo fate of erythrocyte-entrapped enzymes or other therapeutic agents.

Antigens, Surface↗
PubMed1979

Mucopolysaccharidosis in a domestic short-haired cat--a disease distinct from that seen in the Siamese cat.

A 10-month-old male domestic short-haired cat was examined because of progressive lameness, a broad face with depressed nasal bridge, small ears, corneal clouding, and multiple bone dysplasia. The cat excreted excessive amounts of glycosaminoglycan (a component of connective tissue) in its urine and had evidence of lysosomal storage of glycosaminoglycans in fibroblasts and neurons. Activity of alpha-L-iduronidase, a lysosomal enzyme involved in glycosaminoglycan degradation, was deficient in cultured fibroblasts and leukocytes. The mucopolysaccharidosis was distinct from that seen in Siamese cats in terms of the pathologic changes and the specific enzyme deficiency.

Animals↗
PubMed1979

Fetal tissue amino acid concentrations in argininosuccinic aciduria and in "maternal homocystinuria".

Free amino acid concentrations have been measured in the tissues of a fetus at risk for argininosuccinic aciduria and of an obligate heterozygous fetus in a mother homozygous for homocystinuria. Argininosuccinic acid was detected in all tissues studied of the homozygous affected fetus from the heterozygous mother. Abnormal concentrations of methionine and cystathionine were observed in the tissues of the fetus who was an obligate heterozygote for homocystinuria. These abnormal free amino acid concentrations occur early in fetal development and may be related to later brain dysfunction.

Amino Acid Metabolism, Inborn Errors↗
PubMed1979

The ocular manifestations in Fabry's disease.

We present the ocular manifestations in a series of 37 hemizygous male and 25 heterozygous female patients with Fabry's disease. The ocular findings typically do not impair vision, but are unique and diagnostic. Whorl-like corneal deposits were seen in almost all patients and were more severe in the heterozygotes. The lens showed cream-colored anterior capsular deposits, sometimes in striking "propeller" distribution, in one third of the hemizygotes, and in none of the heterozygotes. A faint but unique posterior capsular opacity with a branching radial pattern was seen in 37% of the hemizygotes and 14% of the heterozygotes. Conjunctival vessel aneurysmal dilations and retinal vessel tortuosity were both more frequent and severe in the hemizygotes. Severe visual loss occurred in two hemizygotes as a result of unilateral total central artery occlusions.

Adolescent↗
PubMed1979

Inborn errors of lysosomal catabolism--principles of heterozygote detection.

Carriers of an inborn error of lysosomal catabolism can be recognized, as they have enzyme levels approximately half those of normal individuals. Of the various tissues readily available for assay, plasma and leukocytes and, in some situations, tears are preferred. Although mixed leukocytes have proved satisfactory in Tay-Sachs screening programs, purified preparations of granulocytes or lymphocytes will allow better discrimination in most situations. Enzymes are assayed relative to some other reference parameter which must be a constant or highly correlated with test enzyme activity. In the two mass screening programs in operation, beta-hexosaminidase A and alpha-mannosidase have both been assayed relative to total beta-hexosaminidase activity. Carrier detection is particularly important in X-linked diseases. The techniques used mostly involve hair roots or fibroblasts and depend on random inactivation of the X chromosome. In the mucolipidoses II and III, in which there are a number of deficient enzymes in cells, carriers may be identified on the basis of the ratio of beta-hexosaminidase I1 and I2 to total hexosaminidase.

Animals↗
PubMed1979

Mutational mosaicism and genetic counseling in retinoblastoma.

Mutations may arise throughout an organism's life cycle. Typically, sporadic meiotic mutations give rise to individuals with all their germinal and somatic cells bearing the mutant gene. These mutations may be amorphs (with full penetrance and expressivity) or hypomorphs (with reduced penetrance and expressivity). Mutational mosaicism, however, involves the origin of mutations occurring during mitosis, whether in the parent at some stage prior to reproductive maturity or in the offspring at some time following fertilization. The phenotypic expression and transmission of these new mutations are dependent on the proportion of cells bearing the mutant gene as well as the location of these cells in somatic and/or germinal tissues. Mutational mosaicism was used as a developmental model to analyze 1,500 sporadic and 179 familial cases of retinoblastoma from the world literature. This model provided an interpretation for the origin, onset, and transmissibility of the sporadic unilateral retinoblastoma cases, which represent over 60% of all retinoblastoma patients. The model also permits a reclassification of all transmissible types of retinoblastoma; based on this classification, more accurate risk figures for genetic counseling can be offered. In addition, mutational mosaicism can be extended as a model to other autosomal dominant and X-linked mutations.

Animals↗
PubMed1979

Factors for improved genetic counseling for retinoblastoma based on a survey of 55 families.

Of 55 families in which one or more patients with retinoblastoma were treated, five of these families involved more than one patient. The remaining 50 were sporadic cases. Two of the five familial cases involved collateral inheritance and three involved direct inheritance. Factors important for genetic counseling included the time of onset of first symptoms, the age of the father, the occurrence of a second primary tumor, unilateral vs bilateral involvement, and the cytogenetic analysis of the patient's chromosomes. Additionally, mutational mosaicism was considered as a cause for sporadic cases of retinoblastoma. Use of the risk figures derived from this study should provide more precise genetic counseling for parents, siblings, and patients with retinoblastoma.

Adolescent↗
PubMed1979

Enzyme therapy in Fabry disease: differential in vivo plasma clearance and metabolic effectiveness of plasma and splenic alpha-galactosidase A isozymes.

A pilot trial of enzyme replacement with splenic and plasma alpha-galactosidase A (alpha-D-galactosidase; alpha-D-galactoside galactohydrolase, EC 3.2.1.22) isozymes was undertaken in two brothers with Fabry disease, an X-linked glycosphingolipid storage disease. Six unentrapped doses (2000 units/kg) of each isozyme were administered intravenously to the respective recipients during a 117-day period. The circulating half-life of the splenic isozyme was about 10 min, whereas that for the plasma isozyme was approximately 70 min. No immune response was detected by skin and immunodiffusion tests or by alterations in the maximal activity or clearance kinetics for either isozyme after successive administrations. After each dose of the splenic isozyme, the concentration of the accumulated circulating substrate, trihexosylceramide (globotriaosylceramide), decreased maximally (approximately 50% of initial values) in 15 min and returned to preinfusion levels by 2-3 hr. In marked contrast, injection of the plasma isozyme decreased the circulating substrate levels 50-70% by 2-6 hr; the concentrations gradually returned to preinfusion values by 36-72 hr.

Adult↗
PubMed1979

Metachromatic leukodystrophy without arylsulfatase A deficiency.

Two siblings of consanguinous parents were noted to have a neurologic syndrome marked by developmental delay, regression of psychomotor performance, marked spasticity and progressive central nervous system degeneration. Markedly delayed nerve conduction times and a sural nerve biopsy which demonstrated changes typical of metachromatic leukodystrophy (MLD) were evident. Impairment of sulfated glycolipid metabolism was documented by analysis of glycospingolipid in urinary sediment. In spite of these findings, activities of arylsulfatase A and cerebroside sulfatidase in white blood cells and cultured skin fibroblasts were near normal. However, when intact growing fibroblasts were loaded with 35SO4-sulfatide a clear defect in sulfatide cleavage, comparable to that seen in MLD patients, was observed. Thus, these patients represent a new form of sulfatide storage disease -- MLD characterized by intact enzyme activity in cell homogenates but defective sulfolipid metabolism in vivo and in intact fibroblasts.

Adult↗
PubMed1979

Argininosuccinic aciduria: prenatal studies in a family at risk.

We have monitored two successive pregnancies in a family which we found to be at risk for argininosuccinic aciduria. We measured argininosuccinic acid (ASA) concentrations in amniotic fluid and utilized an indirect assay of ASA lyase activity in cultured amniotic fluid cells. The assay procedure is based on the uptake of 14C from [14C]citrulline and of [3H]leucine into protein. ASA was easily measured in amniotic fluid from the first fetus at risk, whereas none was detectable in control fluids. Amniotic fluid cells cultured from this fetus had only 5.5% of control ASA lyase activity. The pregnancy was terminated, and hepatic ASA lyase activity in the fetus was shown to be about 1.3% of control values. In addition, eight fetal tissues were analyzed for ASA, and all had significant accumulation. ASA was not detected in amniotic fluid from the second fetus at risk, and ASA lyase activity in cultured cells was 80% of control activity. Enzymatic analysis of erythrocyte lysate confirmed the diagnosis of an unaffected child (ASA lyase = 46% of control) and indicated heterozygosity. Thus, we provide further evidence that argininosuccinic aciduria can be diagnosed successfully in utero by indirect assay of ASA lyase activity in cultured amniotic fluid cells. In addition, high amniotic fluid ASA concentrations provide strong adjunctive evidence for such a prenatal determination, and may prove to be sufficient for diagnosis.

Adult↗