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Biomedical subjects

A Feldman

Publications and source records attributed to A Feldman.

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

A method for isolation and partial purification of Trichinella spiralis nurse cells.

Invasion of vertebrate muscle cells by larvae of Trichinella spiralis is accompanied by redifferentiation of the host myofiber into a novel structure called the nurse cell. The nurse cell protects and nurtures the enclosed parasite during its long stay in host muscle. It is anatomically independent of the surrounding uninfected muscle cells and can be isolated from host tissue by mechanical or enzymatic means. Current methods employed for this purpose have yielded only small numbers of nurse cells. An apparatus designed to isolate large numbers of nurse cells and a method for removal of all free larvae and most host muscle debris is described. Homogenization and trypsin digestion of muscle tissue was followed by passage of muscle/parasite suspensions maintained at 37 C through a jacketed glass column fitted with a 40-mesh stainless steel screen at the top and a Nitex screen with 150-microns-diameter pores at the bottom. Nurse cells were retained by the Nitex screen. Density gradient centrifugation using Percoll removed all free larvae and most contaminating muscle debris from nurse cell suspensions. The large quantities of nurse cells made available by this method will allow evaluation of the molecular biology, nutrition, biochemistry, and metabolism of the enclosed parasite and of the Trichinella-modified host muscle cell.

Animals↗
PubMed1994

Hyperphosphatemia in multiple myeloma.

We report three cases of IgG kappa multiple myeloma with pseudohyperphosphatemia. The patients' serum calcium levels were normal, and the hyperphosphatemia was not related to impaired renal function. No hypoparathyroidism was found, and no exogenous phosphate preparation had been given. Since the hyperphosphatemia was of no obvious clinical or physiological significance, as evidenced by normal serum levels of 1,25 dihydroxy vitamin D3, it was diagnosed as spurious and was connected to interference of the paraprotein with the chromogenic assay. In two of the patients major fluctuations in serum phosphate levels were seen, induced by the changes in globulin and paraprotein levels that occurred during therapy and relapse.

Aged↗
PubMed1992

The legal aspects of treating and being treated by an individual infected with human immunodeficiency virus.

Since the first AIDS case was reported in 1981, the AIDS epidemic is spreading dramatically in the United States. In dealing with the prevention of HIV transmission, we need to carefully balance the protection of civil rights that may be devastated by the disclosure of HIV-infection and the protection of public health against HIV infection in the health care setting. Recognizing the need of guidances in this regard, the CDC has issued recommendations regarding the prevention of HIV transmission in the health care setting on the basis of scientific data. In order to assure the acceptance of CDC guidelines in the health care setting, Congress recently passed a law that requires every state to institute CDC guidelines or its equivalent within 1 year. It is hoped that this requirement will ensure that HIV infection control measures are uniform throughout the nations and help HCWs and patients know their legal rights and obligations. Most importantly, the law regulating HIV-infection control will from now on rely on scientific data rather than on the irrational fear of the general public.

Acquired Immunodeficiency Syndrome↗
PubMed1991

Clustering a large number of compounds. 3. The limits of classification.

Clustering is normally used to group items that are similar. In this application of obtaining a diverse sample from the 230,000 compounds in the National Cancer Institute Repository, we cluster to select compounds that are different from the rest, to optimize screening for new leads. With these constraints, our approach yielded many singleton clusters. We can interpret these results as evidence for a limit to classification, contrary to the customary view of chemistry as a study of classes of compounds.

Antineoplastic Agents↗
PubMed1988

Broad-spectrum antiviral activity of the acyclic guanosine phosphonate (R,S)-HPMPG.

(R,S)-9-(3-hydroxy-2-phosphonomethoxypropyl)guanine [(R,S)-HPMPG] exhibits broad spectrum antiviral activity with an ED50 of less than 1 microM against herpes simplex virus (HSV) types 1 and 2, varicella zoster virus, human cytomegalovirus (HCMV) and vaccinia in plaque reduction assays. Wild type HSV-2 and its thymidine kinase deficient variant are equally sensitive to (R,S)-HPMPG. (R,S)-HPMPG is 100-fold more potent than acyclovir (ED50 = 0.45 microM vs. 44 microM, respectively) against HCMV in cell culture, and 10-fold more active than acyclovir in extending survival time in mice intraperitoneally infected with 70 LD50 HSV-1. However, (R,S)-HPMPG is toxic when administered repeatedly at 44 mg/kg/day in uninfected adult mice. The diphosphoryl derivative of HPMPG was enzymatically synthesized and is a competitive inhibitor of HSV-1 DNA polymerase relative to dGTP (K1 = 0.03 microM). HPMPG-PP is 70-fold less active at inhibiting HeLa DNA polymerase alpha than HSV-1 DNA polymerase. At concentrations between 0.3 and 1.5 microM (R,S)-HPMPG inhibited HSV-1 DNA replication greater than or equal to 50% in infected cells as measured by nucleic acid hybridization. Consistent with inhibition of viral DNA synthesis, 6 to 30 microM (R,S)-HPMPG reduces late viral polypeptide synthesis in HSV-1 infected cells. These data indicate that (R,S)-HPMPG is a thymidine kinase independent broad spectrum antiviral drug which is capable of inhibiting viral DNA polymerase.

Acyclovir↗