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Biomedical subjects

J Carlson

Publications and source records attributed to J Carlson.

At least 235 records · Page 13Linked to original sources
PubMed1988

Signal-to-noise ratio and section thickness in two-dimensional versus three-dimensional Fourier transform MR imaging.

The efficiency and quality of three-dimensional Fourier transform (3DFT) magnetic resonance imaging were evaluated and compared with those of 2DFT imaging. For a fixed imaging time and number of sections, 3DFT imaging with conventional spin echoes always had a worse signal-to-noise ratio (S/N) than did 2DFT imaging, when both were optimized with respect to choice of repetition time (TR). With partial-flip magnetic resonance (MR) imaging, S/N was nearly equal for 2DFT and 3DFT imaging when both were optimized with respect to TR and flip angle. 3DFT imaging can have cross-section artifacts that exceed those of 2DFT imaging. For very thin sections these artifacts may be lessened, and 3DFT imaging can achieve this with smaller gradient pulses. Over-all, 3DFT imaging was found to be advantageous only for the very-thin-section imaging and in combination with partial-flip MR imaging.

Fourier Analysis↗
PubMed1988

Time of exposure and risk of HIV infection in homosexual partners of men with AIDS.

We interviewed, and tested for HIV antibody, 117 homosexual men who had been regular sexual partners of men who developed acquired immunodeficiency syndrome (AIDS); 85 tested seropositive. Receptive anal intercourse with the index AIDS case and number of different sexual partners with whom subjects were anally receptive were both risk factors. Controlling for the number of partners with whom subjects were anally receptive, we found that the odds ratio of receptive anal intercourse with the case was infinite (95% confidence intervals, 3.3-infinity) if sexual contact continued up to or beyond the time of diagnosis, while the odds ratio was 1.0 (95% CI 0.3-3.2) if contact ceased before the case's AIDS diagnosis. Risk was not associated with the duration or frequency of contact. Our data suggest that the potential for sexual transmission from an HIV-infected person may be greater close to or after the onset of disease.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Murine monoclonal anti-DNA antibodies bind directly to glomerular antigens and form immune deposits.

The capacity of monoclonal anti-DNA antibodies, derived spontaneously from MRL-lpr/lpr mice, to bind directly to intrinsic glomerular antigens and form immune deposits was evaluated. Two antibodies, H130 (IgM-kappa) and H241 (IgG2a-kappa), bound to normal glomeruli in vitro. This binding was not inhibited by DNAase, but it was, in the case of H130, inhibited by the anti-idiotype anti-H130. Both antibodies also bound to glomerular digests on nitrocellulose. After i.v. injection, however, H241 bound to glomeruli and formed glomerular immune deposits, whereas H130 did not. Similarly, after i.p. injection of H241 hybridomas to normal mice, all mice developed glomerular immune deposits. In contrast, administration of H130 hybridomas, other anti-DNA-producing hybridomas, and other unrelated hybridomas did not lead to glomerular immune deposit formation. We conclude that certain lupus auto-antibodies can form glomerular immune deposits by binding directly to non-DNA antigenic structures that are normally present in extracellular locations within normal glomeruli.

Animals↗
PubMed1987

Renal, volume, and hormonal changes during therapeutic administration of recombinant interleukin-2 in man.

Changes in blood pressure, renal function, and fluid balance were studied in 12 patients receiving intravenous recombinant interleukin-2 (IL-2) (100,000 units/kg every eight hours) over five days for treatment of metastatic melanoma and renal and colorectal cancers. The IL-2 regimen produced progressive hypotension, azotemia, and sodium avidity (fractional excretion of sodium = 0.20 +/- 0.07 percent) despite massive fluid administration (mean: 18.4 liter per five days) and weight gain (mean: 4.0 kg). Plasma renin activity rose. Hypoalbuminemia developed rapidly (3.6 +/- 0.1 g/dl to 2.2 +/- 0.1 g/dl, p less than 0.01) with widespread edema formation despite normal central venous pressures. Hematocrit did not change during the IL-2 period, consistent with a "capillary-leak." Hemodynamic and renal functional changes reversed after the IL-2 regimen was discontinued, but hypoalbuminemia and elevated urinary n-acetyl-glucosaminidase levels persisted after six days. These studies demonstrate widespread hemodynamic and vascular effects of IL-2 administration that limit its safe use and suggest a possible role for the lymphokine in mediating cardiovascular instability under other circumstances, such as endotoxic shock.

Adult↗
PubMed1987

Risk factors for AIDS and HIV seropositivity in homosexual men.

The authors compared cases of acquired immunodeficiency syndrome (AIDS) diagnosed in San Francisco, California, during 1983-1984 with human immuno-deficiency virus (HIV) antibody-negative neighborhood and clinic controls, looking for risk factors for clinical AIDS. They also compared antibody-positive with antibody-negative neighborhood and clinic controls for risk factors for HIV infection. Odds ratios were 52.0 for AIDs and 7.8 for seropositivity for more than 100 sexual partners versus 0-5 partners when antibody-negative neighborhood controls were compared with cases and with antibody-positive neighborhood controls, respectively. Odds ratios were only 2.9 and 3.4 when antibody-negative clinic controls were compared with cases and with antibody-positive clinic controls, respectively. Odds ratios of 4.6-7.3 for rectal receptivity with most or all partners versus none or one partner were statistically significant, independent of the number of partners. Douching before sex was independently associated with odds ratios of 2.2-2.8. There was no evidence for oral-genital, oral-anal, or other sexual transmission of AIDS. In multivariate analysis, independent odds ratios of 2.4-6.0 for prior syphilis and 10.8-27.9 for prior giardiasis were statistically significant or marginally significant in all comparisons. There was a moderate association with nitrite use. No other drugs were consistently associated with clinical AIDS or HIV seropositivity. Odds ratios associated with AIDS and seropositivity were closely comparable except for number of partners.

Acquired Immunodeficiency Syndrome↗
PubMed1987

Unique p24 epitope marker to identify multiple human immunodeficiency virus variants in blood from the same individuals.

The human immunodeficiency virus (HIV) was isolated from the blood of 192 of 410 seropositive individuals. Original isolations were made in peripheral blood mononuclear cell (PBMC) cultures, and only one-fifth of the HIV isolates could be adapted to replicate in continuous T-cell lines. Of the 192 HIV isolates, 42 had the characteristic p24 antigen marker of the acquired immunodeficiency syndrome-associated retrovirus type 2 strain of HIV (HIV ARV-2) and 150 resembled the human T-cell lymphotropic virus type III strain of HIV (HIV HTLV-III). Significantly, primary PBMC cultures from two patients yielded multiple variants. When these variants were exposed to continuous T-cell lines, only one of them continued to replicate. The remaining variants were lost and could not be reisolated following passage back into PBMC cultures. We conclude the following from these studies: PBMC cultures are more efficient at isolating HIV than continuous T-cell lines are; some patients harbor more than one genetic variant of HIV in the blood at the same time; and continuous T-cell lines are likely to yield only a portion of the HIV variants originally present in the blood.

Antigens, Viral↗
PubMed1987

Trimethoprim associated aseptic meningitis.

We report 5 patients with repeated episodes of meningitis related to intake of trimethoprim containing compounds. On at least one occasion the patients received pure trimethoprim prior to reaction. Autoimmune disease was established in 3 of the patients. A close temporal relationship between drug intake and reaction was noted: symptoms appeared often within minutes. No evidence of infections was found. Lumbar puncture after recovery revealed normal values in 2 patients. This aseptic meningitis is most likely an adverse drug reaction and associated with trimethoprim intake. The reaction is infrequently reported in relation to drug sales but its incidence has probably been underestimated.

Adolescent↗
PubMed1986

Risk of cirrhosis and primary liver cancer in alpha 1-antitrypsin deficiency.

Previous reports have suggested an association between homozygous alpha 1-antitrypsin deficiency, cirrhosis, and primary liver cancer. To assess the risk of these complications we conducted a retrospective study based on 17 autopsied cases of alpha 1-antitrypsin deficiency identified during the period 1963 to 1982 in the city of Malmö, Sweden. During the study period, autopsies were performed in 38,250, or 68.2 percent, of all patients in the city who died. From the homozygote frequency in the population, 21 of these were expected to have alpha 1-antitrypsin deficiency. The disease had been diagnosed in 20, and autopsies had been performed in 17 (1 child and 16 adults). Each autopsied case was matched with four controls selected from the same autopsy register, and the Mantel-Haenszel odds ratio (ORmh) was calculated. The results indicated a strong relation between alpha 1-antitrypsin deficiency and cirrhosis (ORmh = 7.8; 95 percent confidence limits, 2.4 to 24.7) and primary liver cancer (ORmh = 20; 95 percent confidence limits, 3.5 to 114.3). When data were stratified according to sex, these associations were statistically significant only for male patients. We conclude that men with alpha 1-antitrypsin deficiency may be at higher risk for cirrhosis and primary liver cancer. The apparent male predominance suggests the additive effects of exogenous factors.

Aged↗
PubMed1986

Risk of seroconversion for acquired immunodeficiency syndrome (AIDS) in San Francisco health workers.

The occupational risk of acquiring acquired immunodeficiency syndrome (AIDS) virus infection in health workers exposed to AIDS patients and specimens was assessed by a serologic study at San Francisco General Hospital and collaborating research laboratories. A total of 101 medical workers without risk factors for AIDS were examined for antibodies to two isolates of the AIDS retrovirus (AIDS-associated retrovirus 2[ARV-2] and human T cell lymphotropic virus III). Most had heavy, long-term exposure to AIDS patients and 29 had been exposed by needlestick or mucocutaneous accident. None of the 101 had antibodies to ARV-2 by immunofluorescence or to HTLV-III by enzyme-linked immunosorbent assay and Western Blot.

Acquired Immunodeficiency Syndrome↗
PubMed1986

Lithium ion transport by erythrocytes of randomly selected blood donors and manic-depressive patients: lack of association with affective illness.

The authors measured the in vitro lithium ion ratio and maximal rate of sodium-lithium countertransport in erythrocytes of 739 randomly selected blood donors and 42 manic-depressive patients to determine the frequency distributions of these two variables in a general population and their relationship to one another and to affective illness. A large interindividual variation was found for the ratio and countertransport, and there was evidence of bimodality in the frequency distributions for these two traits. There was a moderate negative correlation (r = -.61) between the ratio and countertransport for 126 individuals. Neither the ratio nor countertransport was found to be a useful marker for affective illness.

Adult↗
PubMed1985

Enthalpies of ligand binding to bovine neurophysins.

Flow microcalorimetry and batch microcalorimetry have been used to survey the energetics of ligand binding by bovine neurophysins I and II. Calorimetry studies were supplemented by van't Hoff analyses of binding constants determined by circular dichroism. Free energies of binding of a series of di- and tripeptides that bind to the strong hormone binding site of neurophysin were partitioned into their enthalpic and entropic components. The results indicate that, at 25 degrees C, the binding of most peptides is an enthalpy-driven reaction associated with negative entropy and heat capacity changes. Studies elsewhere, supported by evidence here, indicate that the principal component of the negative enthalpy change does not arise from the increase in neurophysin dimerization associated with peptide binding. Accordingly, the negative enthalpy change is attributed to direct bonding interactions with peptide and possibly also to peptide-induced changes in tertiary or quaternary organization. Comparison of the binding enthalpies of different peptides indicated two types of bonding interactions that contribute to the negative enthalpy change of peptide ligation. Substitution of an aromatic- or sulfur-containing side chain for an aliphatic side chain in position 1 of bound peptides led to increases in negative enthalpy of from 1 to 6 kcal/mol, demonstrating that interactions typically classified as hydrophobic can have a significant exothermic component at 25 degrees C. Similarly, loss of hydrogen bonding potential in the peptide decreased the enthalpy change upon binding, in keeping with the expected enthalpic contribution of hydrogen bonds. In particular, the data suggested that the peptide backbone between residues 2 and 3 and the phenolic hydroxyl group in position 2 participate in hydrogen bonding.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗