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Biomedical subjects

M S Baker

Publications and source records attributed to M S Baker.

At least 55 records · Page 3Linked to original sources
PubMed1996

Military medicine in operations other than war. Part II: Humanitarian relief missions for Naval Reserve fleet hospitals.

The U.S. military has a long tradition of providing emergency humanitarian assistance to civilian populations overwhelmed by natural disasters or civil strife. Military medicine is designed primarily to provide operational support for combat-oriented missions. The humanitarian relief mission requires different doctrine, configuration, supplies, and training for proper response. The Naval Reserve Fleet Hospital can be used as a crisis-response asset tasked for this specific mission to lessen the negative impact on active duty military operations and medical treatment facilities.

Hospitals, Military↗
PubMed1996

Preventing post-traumatic stress disorders in military medical personnel.

Medical personnel in military units are highly vulnerable to post-traumatic stress disorder. They are removed from their conventional identity, stature, and social support system, and are deprived of a sense of control and physical comforts. They then must witness and immerse themselves in the gruesome results of warfare. Ideal training of medical personnel includes training intact units and functional teams, training on the deployment platform, and desensitizing with real casualty management. Using stress inoculation techniques prior to casualty handling, and providing for post-event debriefing (Critical Incidence Stress Debriefing), will reduce the incidence of combat casualty-induced stress disorders.

Humans↗
PubMed1995

Pasteurella multocida isolation from a tuboovarian abscess. A case report.

BACKGROUND: Human infection with Pasteurella multocida occurs most commonly following a nonhuman animal bite wound or cat scratch, with local skin and soft tissue infections the most frequent posttraumatic manifestations. Genitourinary tract pathology attributable to this organism occurs infrequently, with only one previous reported case of P multocida infection presenting in the form of a tuboovarian abscess. CASE: A 44-year-old woman with an acute abdomen underwent exploratory laparotomy, revealing a right-sided tuboovarian abscess. Following a total abdominal hysterectomy and bilateral salpingo-oophorectomy with a seven-day postoperative course of intravenous metronidazole, ampicillin and gentamicin, the patient was sent home on a regimen of cephradine, only to return with sepsis three days later. A course of intravenous aqueous penicillin sodium, metronidazole and cefotaxime was administered for the treatment of P multocida sepsis since this organism was identified in the intraoperative pelvic fluid culture 24 hours after the patient's initial discharge. After 13 days of the above regimen, the patient achieved full defervescence and was discharged on hospital day 15. CONCLUSION: In the setting of a tuboovarian abscess, the clinician should consider P multocida as a potential etiologic agent, especially in a patient with extensive exposure to nonhuman animals. In the treatment of an acute adnexal infection secondary to this organism, one should employ perioperative therapy with the appropriate antibiotics for a duration of at least 14 days.

Abscess↗
PubMed1995

A pilot study of DNA aneuploidy in colorectal adenomas and risk of adenoma recurrence.

This case-control study examined whether DNA aneuploidy in colorectal adenomas is a risk factor for subsequent adenoma recurrence. Cases (recurrent polyp formers) were defined as persons with diagnoses of new adenomas at 2 colonoscopies following the index (first) adenoma diagnosis; controls were persons with no new adenomas at a follow-up at least 1 year after the index diagnosis. Cases (n = 22) and up to 3 controls (n = 29) were matched for factors known to be associated with polyp recurrence or aneuploidy: (a) age; (b) histology; (c) number of index polyps; and (d) size of largest index polyp. The largest adenoma from the index colonoscopy was removed from the paraffin block and analyzed for DNA content abnormalities by flow cytometry. On the basis of the observed distribution of aneuploidy in case-control sets, the point estimate for the relative odds of recurrence given aneuploidy in the index polyp was infinity (P < 0.035), and the lower bound for the 95% confidence interval was 2.02. We conclude that in this convenience sample, DNA aneuploidy increased the risk of recurrent colorectal adenomas. Larger, preferably prospective studies are needed before DNA content flow cytometric analysis of colorectal adenomas can be recommended as a routine clinical practice, but these results do suggest that polyp ploidy should be assessed in research studies using adenomas as end points or intermediate end point markers.

Adenoma↗
PubMed1995

Effects of an intensive 12-wk training program by elite swimmers on neutrophil oxidative activity.

The effects of an intensive 12-wk training program by 12 national-level swimmers on neutrophil oxidative activity were studied. Eleven sedentary (untrained) subjects (6 males and 5 females) served as environmental controls. Blood samples (10 ml) were taken at rest from an antecubital vein and neutrophils isolated by standard separation techniques. The oxidative burst activity of isolated neutrophils was assessed with an in vitro flow cytometric assay that used the fluorescent probe dihydrorhodamine 123. Two-way ANOVA (repeated measures) showed that oxidative activity was lower (P < 0.05) in the elite swimmers compared with the sedentary control group across the 12-wk period. Analysis of cells from swimmers in training was made: repeated measures ANOVA provided evidence of a significant decline (P < 0.05) in the number of cells responding positively ito in vitro challenge. Despite this decline, there was no significant difference in self-reported upper respiratory tract infection rate between the swimmers and sedentary individuals. These data show that: (i) elite swimmers undertaking intensive training have a significantly lower neutrophil oxidative activity at rest than do age- and sex-matched sedentary individuals; (ii) aspects of oxidative activity in swimmers are further suppressed during periods of strenuous training, and (iii) the extent of the suppression does not appear to be of clinical significance.

Adult↗
PubMed1994

Advanced trauma life support: is it adequate stand-alone training for military medicine?

Advanced Trauma Life Support (ATLS) is a 2-day course on handling the acutely injured patient. It has been developed by and is directed by the American College of Surgeons, and teaches a systematic approach to the care of the injured patient. It is relied upon as a teaching tool throughout the active and reserve military medical departments. This article will review its strengths and weaknesses, and will show that it is not an adequate "stand-alone" training tool. ATLS does not address the combat casualty, nor the combat scenario. Special courses must be utilized to train military medical providers for the conflicts and casualties of the future.

Humans↗
PubMed1993

Human platelets possess tyrosylprotein sulfotransferase (TPST) activity.

Tyrosine sulfation is a widespread modification of secreted proteins including several coagulation proteins synthesized in the liver. Since factor V, a tyrosine-sulfated protein, is also synthesized in megakaryocytes, we determined whether platelets posses tyrosylprotein sulfotransferase (TPST) activity. Using the synthetic substrate EAY, substantial TPST activity (0.405 +/- 0.049 pmol EAY-SO4 formed min-1 mg-1) was detected in platelet homogenates. This activity could not be accounted for by contaminating leukocytes, erythrocytes or plasma. The Km of platelet TPST for EAY was 3.7 microM and Vmax 0.09 pmol/min. For the cofactor 3' phosphoadenosine 5' phosphosulfate (PAPS) the Km was 1.7 microM and Vmax 0.11 pmol/min. The PAPS analogue 3',5'-adenosine diphosphate inhibited platelet TPST with an IC50 of 15.4 microM. These findings suggest that tyrosine sulfation of factor V will occur in megakaryocytes. Platelets may be a useful source for further study of TPST.

Animals↗
PubMed1993

Granulocyte activation induced by intense interval running.

Activation of granulocytes has been associated with normal immune function, inflammation, and exercise-induced muscle damage. The effect of intense interval running on granulocyte activation was examined by use of flow cytometry, monoclonal antibodies, and spectrophotometric techniques. Eight trained males [maximal oxygen uptake VO2max, mean (SD) = 64.4 (3.6) ml/kg/min; age 30.1 (4.8) years] undertook an intense interval exercise (treadmill running) protocol to exhaustion. Subjects completed an average of 16.5 one-minute runs. Granulocyte expression of CR3 (CD11b), receptor for complement component C3bi (6 and 24 h post-test), and Fc gamma RIII (CD16) (24 h post-test) and the plasma concentration of elastase-inhibitor complex (1 h post-test) increased significantly (all P < .05). Subjects (8 of 8) exhibited a post-test decrease at either 1 or 6 h (P < .01) and a 24-h post-test significant increase (7 of 8; P < .05) in granulocyte 90 degrees light scattering (LS). Plasma lactoferrin (Lf) concentration, although increased by 17% at 6 h post-test, was not significantly different from resting values at any sampling point. Changes in plasma Lf and median channel 90 degrees LS were significantly correlated (r = -.43, P = .04), raising the possibility of monitoring exercise-induced granulocyte activation (degranulation) by flow cytometry. Intense interval exercise appears to induce granulocyte activation, as manifested by release of granule proteins and changes in 90 degrees LS and expression of both Fc and complement receptors.

Adult↗
PubMed1992

Occupancy of the cancer cell urokinase receptor (uPAR): effects of acid elution and exogenous uPA on cell surface urokinase (uPA).

The development of a simple, sensitive fluorimetric assay for the measurement of cell surface-associated urokinase plasminogen activator (uPA) on viable, adherent HCT116 cells in microtitre plates, after a preincubation with purified human plasminogen is described. The assay determines plasmin activity by the cleavage of H-D-Val-Leu-Lys 4-aminomethyl coumarin under near physiological pH and ionic conditions with a sensitivity in the range of 5-100 mIU uPA/well at excitation 355 nm and emission 460 nm. Plasmin generated during the assay converted all cell-surface sc-uPA to tc-uPA, allowing the determination of total uPA activity. Inhibitor studies (PAI-2, amiloride or Glu-Gly-Arg chloromethylketone) confirmed the specificity of the uPA assay. Removal of these agents prior to assay allowed determination of the cell surface sc-uPA:tc-uPA ratio. Cell surface activity was only partially removed by acid elution. This corresponded with the loss of a number of proteins and uPA-containing species as detected by SDS-PAGE, gelatin enzymography and Western blotting. Although the major protein species eluted had a M(r) of 55 kDa, reacted with a commercial anti-human uPA mAb and correlated with the main lytic zone, other higher M(r) species were also eluted from HCT116 cells. Exogenous uPA increased cell-surface activity markedly on cells previously treated with acid. Following acid elution, cell surface uPA activity was restored after 30h in culture suggesting either de novo synthesis or release of pre-formed uPA with subsequent secretion and binding to uPAR. The assay has enabled studies on adherent cells to address questions about the regulation and expression of cell-surface uPA.

Aprotinin↗
PubMed1992

Cytokine immunoreactivity in plasma does not change after moderate endurance exercise.

We investigated whether increased concentrations of circulating cytokines may be responsible for exercise-induced priming of blood neutrophils (J. A. Smith et al. Int. J. Sports Med. 11: 179-187, 1990). The plasma concentrations of tumor necrosis factor-alpha, interleukin- (IL) 1 beta, IL-6, granulocyte-macrophage colony-stimulating factor, and neopterin in trained and untrained human subjects were measured by immunoassay before and after 1 h of cycling at 60% of maximal oxygen uptake. C-reactive protein and creatine kinase (CK) were also measured before and 24 h after exercise as markers of the "acute-phase response" and muscle damage (C. Taylor et al. J. Appl. Physiol. 62: 464-469, 1987), respectively. The small changes in the plasma concentrations of cytokines or neopterin observed after exercise in both trained and untrained subjects were not significantly different to those found in a control group of nonexercised subjects. However, untrained subjects did exhibit an acute-phase response (P = 0.04) 24 h after exercise without additional release of CK into plasma. Baseline training differences were confined to a twofold elevation in CK activity (P = 0.04). The results show that circulating cytokines are unlikely to be responsible for the priming of neutrophil microbicidal activity observed after moderate endurance exercise (J. A. Smith et al. Int. J. Sports Med. 11: 179-187, 1990).

Adult↗
PubMed1992

Free radical generation in hydroperoxide-treated erythrocytes monitored continuously by luminol-amplified chemiluminescence.

Organic hydroperoxides induce oxidative damage to mammalian cells. We describe how luminol-amplified chemiluminescence can be used to monitor free radical generation (following treatment of erythrocytes in vitro with organic hydroperoxides) throughout the entire time-course of oxidative stress. Enrichment of erythrocyte alpha-tocopherol levels increased the induction time by 25% and led peak chemiluminescence fall of 30%. Furthermore, ascorbate loading reduced the signal four-fold during the induction period. The catalytic role of haemoglobin was shown by the abolition of chemiluminescence by azide and a low (but detectable) signal in haemoglobin-depleted erythrocyte ghosts. Luminol-amplified chemiluminescence enables the kinetics of free radical generation to be monitored continuously. Furthermore, it may enable features of the mechanism of interaction between cellular antioxidants and antioxidant enzymes to be elucidated.

Cells, Cultured↗
PubMed1992

The wandering spleen.

Wandering spleen is an unusual entity, occurring in both sexes and at any age, but is more frequent in women of reproductive age and in children. Wandering spleen is probably most often a result of congenital anomalies of development of the dorsal mesogastrium, but acquired factors may have a role in certain instances. Patients present most commonly with an asymptomatic mass, mass and subacute abdominal or gastrointestinal complaints or with acute abdominal findings. Clinical diagnosis can be difficult, but noninvasive imaging procedures, such as sonography, nuclear scintigraphy, computed tomography and magnetic resonance imaging are usually diagnostic. Laboratory tests are usually nonspecific, but may occasionally reveal evidence of hypersplenism or functional splenia. Symptoms may remain limited or absent for long periods of time, but complications related to torsion or compression of abdominal organs by the spleen or the pedicle are quite common. Splenomegaly is usually a result of torsion of the pedicle and splenic sequestration. Significant morbidity and mortality rates seem to be considerably less than described in 1933 and limited primarily to patients presenting initially with acute abdominal findings. Management recommendations have varied, but recognition of a significant risk of postsplenectomy sepsis supports a conservative approach. Patients with limited symptomatology may be medically managed until they exhibit worsening symptoms indicating progressive splenic torsion or gastrointestinal compression. Detorsion and splenopexy may be considered a reasonable surgical option even in patients presenting with acute abdomen, if there is no evidence of infarction, thrombosis or hypersplenism. Splenic preservation is especially recommended in extremely young patients who are at particular risk for postsplenectomy sepsis. However, it should be noted that follow-up evaluation data on splenopexy patients are notably lacking. Splenectomy is ideally reserved for patients presenting with acute abdomen and splenic infarction or thrombosis or with hypersplenism and patients in whom splenopexy is technically unfeasible. Subtotal splenectomy and splenic autotransplantation may be of limited value. Pneumococcal, Hemophilus and meningococcal vaccines are indicated before elective splenectomy and shortly after nonelective splenectomy. Antibiotic prophylaxis is recommended for those at particular risk. Prospective studies are unlikely, but extended follow-up information on patients already reported, particularly those managed expectantly or with conservative surgical measures, is needed.

Congenital Abnormalities↗
PubMed1991

Oxidation of articular cartilage glyceraldehyde-3-phosphate dehydrogenase (G3PDH) occurs in vivo during carrageenin-induced arthritis.

Articular cartilage proteoglycan biosynthesis was substantially inhibited by the competitive glycolytic inhibitor 2-deoxyglucose (approximately 65% at 100 mM), but to a much lesser degree (approximately 10%) by the oxidative phosphorylation uncoupler, 2,4-dinitrophenol. These results confirm that articular cartilage proteoglycan synthesis mostly utilises ATP which is generated by glycolysis. In addition, we have utilised the loss of the relatively specific labelling of glyceraldehyde-3-phosphate dehydrogenase (G3PDH) by [3H]-iodoacetic acid to show that rabbit articular G3PDH is oxidised in vivo during the animal model of acute arthritis, carrageenin-induced arthritis, in the same way as we have previously shown that cartilage G3PDH is oxidised after in vitro exposure to sublethal doses of H2O2. The oxidation of rabbit G3PDH in vivo (18 hr post-injection) corresponds with the maximal influx of PMNL cells into the arthritic synovial fluid and with substantial inhibition of proteoglycan core protein synthesis. We propose that H2O2 released from "activated" PMNLs and macrophages is responsible for the "down-regulation" of biosynthetic processes found in cartilage during acute inflammation.

2,4-Dinitrophenol↗
PubMed1991

The effects of free radical scavengers on arachidonic acid metabolism by ovine placental microsomes.

1. The effect of free radical (superoxide and hydroxyl) and hydrogen peroxide scavengers on the formation of prostaglandin E2 by ovine placental microsomes was investigated. 2. Of the free radical scavengers tested only Mn Desferal, a low molecular weight (712 Da) superoxide scavenger, at concentrations of 0.5-5 mmol/l significantly (P less than 0.001) stimulated PGE2 formation by ovine placental microsomes. 3. This observation is consistent with the involvement of superoxide radicals in the inactivation of prostaglandin G/H synthase (PGHS). 4. The results obtained further suggest that if superoxide radicals are important regulators of PGHS activity in the ovine placenta, they are not accessible to large molecular weight free radical scavengers.

Animals↗
PubMed1991

The oxidant hypochlorite (OCl-), a product of the myeloperoxidase system, degrades articular cartilage proteoglycan aggregate.

The myeloperoxidase-derived oxidant, hypochlorite (OCl-) was shown to be able to degrade proteoglycan aggregate prepared from bovine articular cartilage. Exposure of proteoglycan aggregate to OCl- concentrations less than 10(-4) M resulted in a decrease in the size of the constituent proteoglycan monomers, which were unable to reaggregate with hyaluronate due to the loss of the hyaluronic acid binding region as indicated by immunoblotting using the monoclonal 1-C-6 antibody. Analysis of the [35S]-labeled core proteins by SDS/polyacrylamide electrophoresis and fluorography indicated a decrease in the size of the core protein. These data suggest that concentrations of OCl- below 10(-3) M results in the cleavage of the proteoglycan core protein in or near the hyaluronic acid binding region. The physiological consequences of these data are discussed. Exposure to higher concentrations (greater than 10(-3)) of OCl- caused more extensive degradation of the core protein; however, there was no evidence to suggest that OCl- cleaves glycosaminoglycan (GAG) chains.

Animals↗