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Biomedical subjects

M L Collins

Publications and source records attributed to M L Collins.

At least 19 recordsLinked to original sources
PubMed1992

Localization of methanol dehydrogenase in two strains of methylotrophic bacteria detected by immunogold labeling.

Antibodies to methanol dehydrogenase purified from Methylobacterium sp. strain AM1 and Methylomonas sp. strain A4 were raised. The antibody preparations were used in indirect immunogold labeling studies. With this approach, methanol dehydrogenase was found to be preferentially localized to the periplasmic region of the methylotroph Methylobacterium sp. strain AM1 and to the intracytoplasmic membrane of the methanotroph Methylomonas sp. strain A4. Antibody cross-reactivity to other methylotrophic bacteria was detected.

Alcohol Oxidoreductases↗
PubMed1992

Aerosolized Pseudomonas elastase and lung fluid balance in anesthetized sheep.

The role of the lung epithelium in lung fluid balance was studied by ventilating anesthetized sheep with an aerosol of 20 mg of elastase from Pseudomonas aeruginosa (Ps. elastase) to increase lung epithelial permeability without affecting lung endothelial permeability or lung vascular pressures. Ps. elastase had no effect on the lung vascular pressures, the alveolar-arterial PO2 gradient (A-aPO2), the flow or protein concentration of the lung lymph, or the postmortem water volume of the lungs. The morphological alveolar flooding score in these sheep was 2.5 times the control level, but this was only marginally significant. Elevation of the left atrial pressure by 20 cmH2O alone increased the postmortem lung water volume but had no effect on A-aPO2, the alveolar flooding score, or the lung epithelial permeability assessed by the clearance of 99mTc-labeled human serum albumin. Addition of aerosolized Ps. elastase to these sheep had no effect on the total lung water volume, but it caused a redistribution of water into the air spaces, as evidenced by significant increases in the alveolar flooding score and A-aPO2 (P less than 0.01). Elevation of the left atrial pressure by 40 cmH2O without elastase caused the same response as elevation of the left atrial pressure by 20 cmH2O with elastase, except the higher pressure caused a greater increase in the total lung water volume. We conclude that alteration of the integrity of the lung epithelium with aerosolized Ps. elastase causes a redistribution of lung water into the alveoli without affecting the total lung water volume.(ABSTRACT TRUNCATED AT 250 WORDS)

Aerosols↗
PubMed1992

Recovery following orthognathic surgery and autologous blood transfusion.

Patients undergoing maxillary surgery, with or without mandibular surgery, were divided into two groups. One surgeon's patients served as controls and did not receive blood unless hemodynamically indicated. The remaining surgeons' patients were transfused regardless of their hemoglobin levels following surgery. An attempt was made to identify benefits or complications associated with the reinfusion of autologous blood, particularly in patients with "low blood loss." Patients were asked to record when they returned to their presurgical level of activity. Of the 46 patients in the study 14 (12 nontransfused, two transfused) were not back to full activity 6 weeks after surgery. Of the 32 patients that reported a return to full activity within the study period, transfused patients reported a significantly quicker return to full activity at 2 weeks, 3 weeks, and 4 weeks postoperatively than did their nontransfused counterparts, even when blood loss at surgery was minimal. No complications have occurred with this practice.

Adolescent↗
PubMed1991

Construction, characterization, and complementation of Rhodospirillum rubrum puf region mutants.

Rhodospirillum rubrum is a facultatively phototrophic bacterium that, under certain growth conditions, forms an intracytoplasmic chromatophore membrane (ICM) housing the photochemical apparatus. The puf operon of R. rubrum encodes protein subunits of the photochemical reaction center and the B880 light-harvesting antenna complex. Mutant strains of R. rubrum were constructed by interposon mutagenesis through which a kanamycin resistance gene cartridge was inserted into restriction sites and in place of restriction fragments of the puf region. Southern blot analysis demonstrated that the defective copies of puf sequences had replaced their normal chromosomal counterparts through homologous recombination. The phenotypes of the mutant strains were evaluated on the basis of puf gene expression, spectral analysis, pigment content of membranes, and electron-microscopic examination of thin sections of cells grown under semi-aerobic and dark anaerobic conditions. Alterations of the puf region affect phototrophic competence and the formation of the ICM. The latter result implies an obligatory role for puf gene products in ICM formation in R. rubrum. One mutant with a deletion in puf structural genes was complemented in trans to the wild-type phenotype. Other mutants could be restored to the wild-type phenotype only by recombination.

Blotting, Northern↗
PubMed1991

Rewash bronchoalveolar lavage.

A significant limitation of standard bronchoalveolar lavage (BAL) technique is the inability to measure or calculate epithelial lining fluid (ELF) volume and, therefore, in vivo concentrations of substances in the ELF. We evaluated a new rewash BAL procedure with the radiolabeled tracer technetium pertechnetate (99mTcO4-) that theoretically should be immune to even exaggerated fluid shifts during BAL. To test this theory, we measured ELF volume in control sheep using isosmotic (280 mosm/L) hypoosmotic (140 mosm/L) and hyperosmotic (570 mosm/L) BAL solutions to induce exaggerated fluid shifts during the lavage procedure. The mean ELF volume of the lavaged lung segment was not significantly different for the three solutions (isosmotic, 1.7 +/- 0.8 ml; hypoosmotic, 1.1 +/- 1.2 ml; hyperosmotic, 2.1 +/- 1.6 ml). The slope of the 99mTcO4- disappearance curve, however, was significantly steeper for the hyperosmotic solution (-0.40 +/- 0.04%/min) compared with the other solutions (isosmotic, -0.14 +/- .01%/min; hypoosmotic, -0.12 +/- 0.07%/min). Calculation of ELF volume using sodium as an endogenous tracer gave consistently smaller values with each of the mannitol solutions (isosmotic, 0.21 +/- 0.30 ml; hypoosmotic, 0.02 +/- 0.03 ml; hyperosmotic, 0.18 +/- 0.18 ml). The failure of sodium to provide accurate estimates of the ELF volume may be due to complicated sodium movement in the lung and errors in our assumption of the initial concentration of sodium in the ELF fluid. We conclude that the rewash BAL technique with 99mTcO4- gives values of ELF volume that are not significantly affected by even exaggeration of the fluid flux that invariably accompanies BAL.

Animals↗
PubMed1990

Detection in non-erythroid cells of a factor with the binding characteristics of the erythroid cell transcription factor EF1.

The erythroid transcription factor erythroid factor-1 (EF1) plays a critical role in the transcription of erythroid-specific genes. Here we report the presence of a factor with the mobility and sequence-specific DNA-binding characteristics of EF1 at low abundance in a wide variety of non-erythroid cell types. This is the first report of an EF1-like activity in non-erythroid cells and indicates that this factor may play a role in the regulation of genes expressed in such cells.

Animals↗
PubMed1990

Optic nerve head swelling and optic atrophy in the systemic mucopolysaccharidoses.

The ocular findings in 108 patients representative of all types of mucopolysaccharidoses (MPS) were reviewed. Attention was focused on optic nerve head appearance. Optic nerve head swelling was observed in 8/14 eyes of MPS 1-Hurler (MPS 1-H); 9/21 MPS 1-Hurler-Scheie (MPS 1-H-S); 0/4 MPS I-S; 13/66 MPS II; 1/22 MPS III; 0/58 MPS IV; 5/12 MPS VI; and 2/2 MPS VII eyes. In three patients, optic nerve head swelling was present in one eye and optic atrophy in the fellow eye; in four patients, optic atrophy followed disc elevation; three patients presented with bilateral optic atrophy. It was concluded that optic nerve head swelling precedes the development of optic atrophy in the systemic MPS.

Adolescent↗
PubMed1990

Effects of Pseudomonas aeruginosa elastase on alveolar epithelial permeability in guinea pigs.

Elastase-deficient mutants of Pseudomonas aeruginosa are less virulent than the wild type and are easily cleared from the lungs of guinea pigs. The effect of P. aeruginosa elastase on lung epithelium, however, is not yet understood. We addressed the hypothesis that breach of the epithelial barrier by elastase from P. aeruginosa allows invading organisms and toxic substances to penetrate the interstitium. We measured the clearance of aerosolized technetium-labeled albumin (molecular weight, 69,000) from the lungs of anesthetized guinea pigs with the aid of a gamma camera and a dedicated computer. Aerosols of the elastase (0.1 to 5 micrograms) increased the rate of clearance of labeled albumin from the lungs in proportion to the elastase dose. Electron microscopic studies using horseradish peroxidase as a tracer revealed that elastase interrupts intercellular tight junctions of the epithelial lining, thereby increasing the permeability to macromolecules. The amounts of elastase used in this report did not cause interstitial or alveolar edema, as determined by both postmortem extravascular lung water volume measurement and morphological examination. The data indicate that the elastase is a potentially important virulence factor in acute lung infection.

Animals↗
PubMed1989

Increased preoperative collection of autologous blood with recombinant human erythropoietin therapy.

To study whether the administration of recombinant human erythropoietin increases the amount of autologous blood that can be collected before surgery, we conducted a randomized, controlled trial of erythropoietin in 47 adults scheduled for elective orthopedic procedures. The patients received either erythropoietin (600 units per kilogram of body weight) or placebo intravenously twice a week for 21 days, during which time up to 6 units of blood was collected. Patients were excluded from donation when their hematocrit values were less than 34 percent. All patients received iron sulfate (325 mg orally three times daily). The mean number of units collected per patient (+/- SE) was 5.4 +/- 0.2 for the erythropoietin group and 4.1 +/- 0.2 for the placebo group. The mean red-cell volume donated by the patients who received erythropoietin was 41 percent greater than that donated by the patients who received placebo (961 vs. 683 ml, P less than 0.05). Only 1 of the 23 patients treated with erythropoietin was unable to donate greater than or equal to 4 units (4 percent) as compared with 7 of the 24 patients who received placebo (29 percent). No adverse effects were attributed to erythropoietin. We conclude that recombinant human erythropoietin increases the ability of patients about to undergo elective surgery to donate autologous blood.

Adult↗
PubMed1989

Nucleic acid hybridization assays employing dA-tailed capture probes. I. Multiple capture methods.

A quantitative hybridization assay termed "reversible target capture" is described. The technique is designed to extensively purify the target nucleic acid from crude cell lysates in about 1 h without phenol extraction. Simple, rapid methods are described that explain how each process in the assay is optimized. The procedure involves hybridizing the target nucleic acid in solution with a dA-tailed capture probe and a labeled probe. The capture probe-target-labeled probe "ternary complex" is then captured on magnetic beads containing oligo(dT). After the excess unhybridized labeled probe, cell debris, and other sample impurities are washed away, the intact ternary complex is further purified by chemical elution from the beads and recapture on fresh beads. The ternary complex is then eluted thermally and recaptured on a third set of beads or on poly(dT) filters. This triple capture method results in a detection limit of approximately 0.2 amol (100 fg) of target with 32P-labeled riboprobes. This is approximately 1000 times more sensitive than sandwich assays employing only a single capture step. The method is illustrated by detecting Listeria cells in the presence of heterologous bacteria. With three rounds of target capture, as few as six Listeria cells have been detected in the presence of 1.25 x 10(7) control cells.

Buffers↗
PubMed1989

Nucleic acid hybridization assays employing dA-tailed capture probes. II. Advanced multiple capture methods.

A fourth capture is added to the reversible target capture procedure of the preceding paper. This results in an improved radioisotopic detection limit of 7.3 x 10(-21) mol of target. In addition, the standard triple capture method is converted into a nonradioactive format with a detection limit of under 1 amol of target. The principal advantage of nonradioactive detection is that the entire assay can be performed in about 1 h. Nucleic acids are released from cells in the presence of the ('capture probe') which contains a 3'-poly(dA) sequence and the ('labeled probe') which contains a detectable nonradioactive moiety such as biotin. After a brief hybridization in solution, the target is captured on oligo(dT) magnetic particles. The target is further purified from sample impurities and excess labeled probe by recapture either once or twice more on fresh magnetic particles. The highly purified target is then concentrated to 200 nl by recapture onto a poly(dT) nitrocellulose filter and rapidly detected with streptavidin-alkaline phosphatase using bromochloroindolyl phosphate and nitroblue tetrazolium. Using this procedure, as little as 0.25 amol of a target plasmid has been detected nonradioactively in crude samples in just 1 h without prior purification of the DNA and RNA. Finally, a new procedure called background capture is introduced to complement the background-reducing power of RTC.

Biotin↗
PubMed1989

Nucleic acid hybridization assays employing dA-tailed capture probes. Single capture methods.

Several novel hybridization techniques are described. Cells or specimens are treated to release nucleic acids and a liquid phase hybridization is carried out with a dA-tailed capture probe and a reporter probe in chaotropic salts or in salts containing SDS/proteinase K. In another format the tailed capture probe is preimmobilized on polystyrene and used to capture target nucleic acids from the solution. No phenol extraction or centrifugation is required to prepare the nucleic acids. Capture of the target on the poly (dT)-solid supports is used to remove excess labelled probe and sample impurities prior to non-radioisotopic or radioisotopic detection. This paper shows the advantage of a single round of capture on polystyrene, including the ability to assay large numbers of samples manually, the ability to analyse each sample for many analytes simultaneously, the use of rapid non-radioisotopic detection, and the ability to readily adapt the assay for automation.

Nucleic Acid Hybridization↗
PubMed1989

Serological studies of peptostreptococci using an indirect fluorescent antibody test.

Members of the genus Peptostreptococcus are frequent isolates from periodontal lesions. A study was undertaken for determination of the serological relationships of oral and non-oral strains of several species of this genus. Eighty-nine strains of peptostreptococci representing seven species were tested by means of an indirect fluorescent antibody technique (IFA), with rabbit antisera to Peptostreptococcus anaerobius ATCC 27337, Peptostreptococcus micros VPI 2618-A, and Peptostreptococcus productus ATCC 27340. Each antiserum showed positive fluorescence when reacted with homologous cells. When anti-P. micros VPI 2618-A serum was added to suspensions of P. micros ATCC 33270 and clinical isolates of P. micros in the IFA, positive fluorescence was observed to a titer of 1:64 with 26 out of 29 strains. Positive fluorescence was also seen when P. anaerobius VPI 5737 and clinical isolates of P. anaerobius were tested with anti-P. anaerobius ATCC 27337 serum; a titer of at least 1:64 was observed in 10 out of 14 strains. These results support the presence of two serological groups of P. anaerobius, rabbit anti-P. anaerobius ATCC 27337 serum reacting with Group II organisms. No interspecies cross-reactivity was observed except with four strains of Peptostreptococcus magnus, which reacted with several antisera as well as with normal rabbit serum and the saline controls. These results indicate that rabbit antisera and the use of an IFA are useful in the identification of P. anaerobius and P. micros from oral lesions.

Fluorescent Antibody Technique↗
PubMed1988

Autologous blood storage in obstetrics.

Autologous transfusion, storage of one's own blood for subsequent infusion if needed, is safe and effective in a variety of scheduled operative procedures. Obstetric involvement in such programs is very limited, however. Thirty pregnant women with placenta previa or other potential complications underwent 55 phlebotomies in an autologous transfusion program. Phlebotomies were performed at an average gestational age of 32.4 weeks (range 13-40). Changes in mean diastolic blood pressure and pulse were minimal. Electronic fetal monitoring tracings were normal during the 34 procedures in which it was used. The frequency of mild donor reactions (4%) was consistent with that in nonpregnant donors. After entry into this program, 15 patients received a total of 29 U of packed red blood cells (23 autologous; six homologous). Homologous transfusion was avoided in 86.7% of patients receiving blood. Selected pregnant women can participate safely in autologous blood collection programs, minimizing the need, and therefore the risks, of homologous transfusion.

Blood Preservation↗
PubMed1987

Predeposited autologous blood for elective surgery. A national multicenter study.

To determine the extent to which autologous blood that has been donated in advance ("predeposited") is used in patients undergoing elective surgery and to assess whether predonation decreases the use of homologous blood and the demand on the blood supply, we studied 4996 patients undergoing elective surgery at 18 tertiary care hospitals. Cross-matched blood was ordered for 1287 patients (26 percent), and of these, 590 (46 percent) were considered eligible for predepositing blood. Only 5 percent (32) of the eligible patients actually predeposited blood, indicating that predonation is not widely used. Of those who predeposited, only 13 percent (4 of 32) subsequently received homologous blood, as compared with 36 percent (199 of 558) of those who did not predeposit (P less than 0.01). Among the 199 patients who did not predeposit but required transfusion, we estimate that predonation could have avoided homologous transfusion in as many as 68 percent. If all eligible patients had predeposited autologous blood, they could have supplied as much as 72 percent of their own transfused red cells. The blood for as much as 10 percent of all red-cell transfusions could have been predonated by and transfused into the patients undergoing elective surgery. Greater use of predonation would not only reduce the demand on the blood supply by decreasing the need for homologous transfusion, but would probably also reduce the risk of hepatitis and other transfusion-associated illnesses.

Blood Banks↗
PubMed1987

Monoclonal antibodies to purified ricin A-chain: production and properties.

Ricin A-chain was purified from native ricin using lactosyl-Sepharose. It was non-toxic to whole cells at a concentration of 1 microM yet nearly as effective as an equimolar concentration of ricin in blocking in vitro protein synthesis. Hybridomas secreting monoclonal antibodies to ricin A-chain were produced using the murine myeloma cell line NS-1. These anti-ricin A-chain antibodies cross-reacted with whole ricin but exhibited little cross-reactivity with purified ricin B-chain. Antibodies 2F2 and 2F5 both immunoprecipitated ricin A-chain. Both antibodies also precipitated ricin B-chain, as did the irrelevant control antibodies MOPC-21 and MPC-11. Pre-incubation of B-chain with 0.1 M galactose eliminated greater than 90% of precipitation by 2F2, MOPC-21 and MPC-11 but effected minimally precipitation by 2F5. Enzyme-linked immunosorbent assays using antibodies 2F2 and 2F5 to detect ricin A-chain in murine or human serum were linear between 40 and 800 ng ricin A-chain per ml. Anti-ricin A-chain antibodies 2F2 and 2F5 produced some inhibition of in vitro A-chain catalytic activity. Specific monoclonal antibodies to A-chain hemitoxin will be useful for characterization of functional hemitoxin domains, in in vitro assays for the stability of A-chain immunotoxins, and in characterizing the cellular internalization and processing of conjugates containing ricin or ricin A-chain.

Animals↗
PubMed1987

Interpretation of red cell survival data for in vivo compatibility testing: a normal value study.

Short-term survival studies are sometimes required to determine the compatibility of donor red cells. The results of these studies are generally expressed as per cent survival at 60 min. The present study was undertaken to investigate the potential for more sophisticated data analytical techniques to improve sensitivity. In one group of eight healthy male volunteers, autologous red cells were labelled with 51chromium and injected immediately, while in a second group, red cells were stored for 5 d prior to injection. In both groups, eight to 10 samples were collected in the first 6 h and another 10-12 samples over the next 4 weeks. Estimation of the 60 min per cent survival was insufficiently sensitive to detect 'physiological' haemolysis following injection of 5-d-old autologous blood. Regression analysis of 6 h survival data, however, demonstrated significantly higher red cell clearance rates in these cases than in those receiving fresh cells, with a mean 24 h loss of 3.3% of activity. The upper limit for the 6 h red cell clearance rate was 1.63%/h after fresh autologous blood and 2.43%/h after 5-d-old blood. The significance of these findings is discussed and a protocol suggested for the analysis of short-term red cell survival data.

Adult↗