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Biomedical subjects

M Katzman

Publications and source records attributed to M Katzman.

34 records · Page 2Linked to original sources
PubMed1992

Hepatobiliary infections caused by Haemophilus species.

Haemophilus species are rarely associated with hepatobiliary infections. We report a case of hepatic abscess caused by Haemophilus paraphrophilus and review the English-language literature for reports of infections of the liver and biliary system caused by Haemophilus species. Most patients identified had predisposing conditions. The pathogenesis of hepatobiliary infections due to Haemophilus species may involve ascending spread from the gastrointestinal tract or hematogenous seeding following oropharyngeal colonization.

Adult↗
PubMed1992

High incidence of bronchospasm with regular administration of aerosolized pentamidine.

A systematic evaluation of changes in pulmonary status by objective spirometric assessment and subjective rating using visual analog scale was performed in a cohort of 134 patients receiving aerosolized pentamidine (AP) for the prevention of Pneumocystis carinii pneumonia. Significant bronchospasm defined as greater than or equal to 15 percent reduction in the forced expiratory volume in 1 s was noted in 26 of 100 (26 percent) of patients receiving AP alone. Despite the use of salbutamol (albuterol) as concurrent aerosolized treatment in 34 subjects, bronchospasm developed in 9 of 34 (26 percent) of the patients. The subjective respiratory status rating scale was found to be unreliable in correctly predicting the development of bronchospasm. We conclude that a high incidence of bronchospasm is present in patients receiving regular AP administration using an ultrasonic nebulizer as studied, and concurrent administration of salbutamol is not fully protective of this acute adverse pulmonary reaction.

Aerosols↗
PubMed1991

A covalent complex between retroviral integrase and nicked substrate DNA.

Purified retroviral integrase (IN) from avian sarcoma-leukosis viruses can appropriately process the termini of linear viral DNA, cleave host DNA in a sequence-independent manner, and catalyze integrative recombination; an exogenous source of energy is not required for these reactions. Using DNA substrates containing radioactive phosphate groups, we demonstrate that IN becomes covalently joined to the new 5' phosphate ends of DNA produced at sites of cleavage. Most of the phosphodiester linkages between IN and DNA involve serine, but some involve threonine. Computer-assisted alignment of 80 retroviral and retrotransposon IN sequences identified one serine that is conserved in all of these proteins and three less-conserved threonine residues. These results identify candidate active-site residues and provide support for the participation of a covalent IN-DNA intermediate in retroviral integration.

Amino Acid Sequence↗
PubMed1991

Overlapping retrovirus U5 sequence elements are required for efficient integration and initiation of reverse transcription.

A secondary structure in the 5' noncoding region of avian retrovirus RNA, called the U5-leader stem, was shown previously to have a role in initiation of reverse transcription (D. Cobrinik, L. Soskey, and J. Leis, J. Virol. 62:3622-3630, 1988). We now show that an additional RNA secondary structure near the U5 terminus, called the U5-IR stem, is also important for reverse transcription. Mutations that disrupt the U5-IR stem cause a replication defect associated with both a decrease in synthesis of viral DNA in infected cells and a decrease in initiation of reverse transcription in melittin-permeabilized virions. Structure-compensating base substitutions in the U5-IR restore reverse transcription efficiency. In viral DNA, U5-IR sequences are included in the U5 terminal region that functions as a viral integration donor site. When base substitutions are introduced into these sequences, a reduced efficiency of integration in vitro and in vivo is observed. These observations indicate that U5-IR sequences have a structural role in reverse transcription of viral RNA and a sequence-specific role in the integration of viral DNA.

Avian Sarcoma Viruses↗
PubMed1989

The avian retroviral integration protein cleaves the terminal sequences of linear viral DNA at the in vivo sites of integration.

The purified integration protein (IN) of avian myeloblastosis virus is shown to nick double-stranded oligodeoxynucleotide substrates that mimic the ends of the linear form of viral DNA. In the presence of Mg2+, nicks are created 2 nucleotides from the 3' OH ends of both the U5 plus strand and the U3 minus strand. Similar cleavage is observed in the presence of Mn2+ but only when the extent of the reaction is limited. Neither the complementary strands nor sequences representing the termini of human immunodeficiency virus type 1 DNA were cleaved at analogous positions. Analysis of a series of substrates containing U5 base substitutions has defined the sequence requirements for site-selective nicking; nucleotides near the cleavage site are most critical for activity. The minimum substrate size required to demonstrate significant activity corresponds to the nearly perfect 15-base terminal inverted repeat. This in vitro activity of IN thus produces viral DNA ends that are joined to host DNA in vivo and corresponds to an expected early step in the integrative recombination reaction. These results provide the first enzymatic support using purified retroviral proteins for a linear DNA precursor to the integrated provirus.

Avian Leukosis Virus↗
PubMed1989

Serious infectious complications of corticosteroid therapy for COPD.

We report seven elderly patients with COPD who developed serious infectious complications during prolonged treatment with high doses of corticosteroids. Infections included invasive pulmonary aspergillosis, Herpes simplex stomatitis and esophagitis, cytomegalovirus pneumonia, bacterial sepsis, fungemia and meningitis due to Cryptococcus neoformans. Each of the three patients who developed invasive aspergillus pneumonia died. The efficacy of prolonged therapy with high doses of corticosteroids in patients with COPD is not proven. These cases illustrate the potential for serious infections in patients with COPD treated with corticosteroids.

Aged↗
PubMed1988

Properties of avian sarcoma-leukosis virus pp32-related pol-endonucleases produced in Escherichia coli.

The gag-pol precursor protein of the avian sarcoma-leukosis virus is processed into three known pol-encoded mature polypeptides; the 95- and 63-kilodalton (kDa) beta and alpha subunits, respectively, of reverse transcriptase and the 32-kDa pp32 protein. The pp32 protein possesses DNA endonuclease activity and is produced from the precursor by two proteolytic cleavage events, one of which removes 4.1 kDa of protein from the C terminus. A 36-kDa protein (p36pol) which retains this C-terminal segment is detectable in small quantities in virions. We have constructed Escherichia coli plasmid clones that express the C-terminal domains of pol corresponding to pp32 and p36. These proteins have been purified by column chromatographic methods to near homogeneity. No significant differences could be detected in the enzymatic properties of the bacterially produced p32pol and p36pol proteins. Both possess DNA endonuclease activity and, like the pp32 protein isolated from virions, can cleave near the junction of two tandem avian sarcoma-leukosis virus long terminal repeats in double-stranded supercoiled DNA substrates. In the presence of Mg2+, both p32pol and viral pp32 cleave either strand of DNA 2 nucleotides 5' to the junction.

Amino Acid Sequence↗
PubMed1988

Cardiomyopathy associated with the acquired immune deficiency syndrome.

Three cases of congestive cardiomyopathy complicating the acquired immune deficiency syndrome (AIDS) are reported. In one case, acute cardiac decompensation resulted in prolonged but ultimately reversible cardiogenic shock. In the second case, clinical signs of cardiac disease were precipitated by acute renal failure and fluid overload. In the third, congestive heart failure developed spontaneously and responded promptly to administration of diuretics but the patient died suddenly, apparently due to an arrhythmia. The etiology of cardiomyopathy in AIDS is unclear and the manifestations of cardiomyopathy in this setting range from subclinical to life threatening.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Molluscum contagiosum and the acquired immunodeficiency syndrome: clinical and immunological details of two cases.

We report here the clinical and immunological findings in two patients with molluscum contagiosum poxvirus infection and the acquired immunodeficiency syndrome (AIDS). These cases support earlier evidence that the molluscum contagiosum virus may act as cases support earlier evidence that the molluscum contagiosum virus may act as an opportunistic pathogen. There is now evidence that members of all five families of double stranded DNA-containing human viruses have been associated with unusual clinical manifestations in AIDS patients, and the significance of DNA virus infections in patients with AIDS is discussed.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Fibronectin and cellular cytotoxicity: evidence against a role for fibronectin in natural killer activity.

We investigated a possible role for fibronectin (Fn) in natural killer (NK) cell activity against K562 tumor cells. Plastic plates that had been incubated with Fn at 60 micrograms/ml bound 49.6% +/- 12.8% (mean +/- SEM) of K562 cells; plates coated with three other proteins bound essentially no tumor cells (P less than 0.01). In similar experiments, 12.6% +/- 4.7% of nonadherent lymphocytes bound to plates that had been coated with 60 micrograms/ml Fn; plates coated with other proteins bound less than or equal to 10% of these cells. Lymphocytes that bound to Fn-coated plates appeared to be slightly enriched for NK cells as assessed by morphology and by cytotoxic activity. Despite these findings, neither NK cytotoxic activity nor binding to K562 targets was affected by the addition of any of three anti-Fn antibody preparations, nor by the addition of exogenous Fn at concentrations found in plasma (300 micrograms/ml). Although Fn appears to bind both to K562 targets and to lymphocyte preparations that contain NK cells, it does not appear to have a functional role in mediating NK cell activity against K562 tumor cells.

Cell Adhesion↗
PubMed1986

Defective postbinding lysis underlies the impaired natural killer activity in factor VIII-treated, human T lymphotropic virus type III seropositive hemophiliacs.

We investigated the diminished natural killer (NK) activity in human T lymphotropic virus type III (HTLV-III) seropositive hemophiliacs. Despite normal percentages of NK cells, lymphocytes from five hemophiliacs showed impaired NK activity against K-562 tumor cells in 4-h chromium release microcytotoxicity assays. For example, at an effector-to-target cell ratio of 10:1, cells from patients caused 21.7 +/- 2.5% lysis of tumor targets compared with 47.9 +/- 5.1% lysis by cells from controls (mean +/- SEM, P less than 0.005). Cells from patients were as cytotoxic in 18 h as were cells from controls in 4 h. Binding to tumor targets was not impaired since 11.0 +/- 1.5% of cells from patients and 11.1 +/- 1.3% of cells from controls bound to K-562 cells. Patients' binding cells, however, showed defective killing of attached tumor cells at all time points tested from 0 to 18 h. At 4 h, for example, patients' cells had lysed 10.9 +/- 2.1% of attached tumor cells compared with 26.3 +/- 3.3% lysis by controls' cells (P less than 0.005). The percentage of lymphocytes which were active NK cells (i.e., cells that bound and lysed a tumor cell) was always lower for patients than for controls (1.17 +/- 0.25% vs. 2.82 +/- 0.33%, P less than 0.005). Two methods for estimating recycling of effector cells against multiple target cells demonstrated that active NK cells from patients could recycle as well as those from controls (approximately 3-4 times in 4 h). Mixing experiments showed no evidence for cellular suppression of NK activity. The lytic function of NK cells from HTLV-III seropositive hemophiliacs is thus heterogeneous. This is characterized by a defect in post-binding lysis, with relative sparing of binding capability and recycling capacity.

Adult↗
PubMed1985

Freestanding emergency centers: regulation and reimbursement.

The freestanding emergency center, which combines the functions of a doctor's office and a hospital emergency room, has emerged as a new provider of health care. These centers have generated considerable controversy over their role in the health care market. Proponents argue that freestanding emergency centers reduce costs by providing care in a more efficient manner and cause other health care providers such as hospital emergency rooms to reduce costs and improve service. Opponents argue that the centers create an additional layer of health care which duplicates existing services and increases total health care costs. This Note examines the controversial issues of licensure, regulation and reimbursement. The Note concludes that freestanding emergency centers can help to reduce health care costs and discusses the steps that should be taken to aid centers in achieving this goal. reduce health care costs and discusses the steps that should be taken to

Ambulatory Care Facilities↗