Biomedical subjects

D R Martin

Publications and source records attributed to D R Martin.

At least 37 records · Page 2Linked to original sources

PubMed2000

Elevated blood pressure in men accompanying patients to the obstetrician's office.

Hypertension is common and leads to increased mortality among adults; yet, one-third of hypertensive adults in the United States are unaware of their condition. The purpose of this study was to determine the frequency of unrecognized elevated blood pressure (BP) in men accompanying pregnant women to the obstetrician's office. Blood pressure measurements were offered to men accompanying pregnant women to four obstetrics practices in St. Louis, Missouri. Age, race, history of hypertension, and relationship to the pregnant woman were also recorded. A total of 191 men participated in the study. Participants' ages ranged from 15 to 69 years, with a mean of 27 years. Elevated BP (> 140/90 mm Hg) was detected in 40 men (21%). Only 5% of men with an elevated BP were aware of a prior history of elevated BP. We conclude that the obstetrician's office provides a good opportunity for initial screening for hypertension in men. Follow-up is necessary to determine the accuracy of the diagnosis.

Adolescent↗

PubMed2000

A molecular description of the gelation mechanism of konjac mannan.

A molecular level description of the time course of the gelation of the polysaccharide konjac mannan (KM) is presented and the role of alkali addition is considered in detail. NMR relaxometry is utilized as a complementary methodology to mechanical spectroscopy in order to probe events occurring as a prelude to network formation, and high-resolution NMR is used to follow the deactetylation process. It is shown that the addition of alkali plays an important solubilizing role in addition to facilitating the deacetylation of the chain. Deacetylation is important both in reducing the inherent aqueous solubility of the polymer and in progressively negating the alkali-induced polyelectrolytic nature of the polysaccharide chain via reaction induced pH changes. It is proposed that observed induction periods following alkali addition (during which the elastic modulus does not rise) are not simply deacetylation delays but are related to the aggregation kinetics of the deacetylated material.

Algorithms↗

PubMed2000

Expression of CD44 in kidney after acute ischemic injury in rats.

De novo CD44 and ligand expression at wound margins accompanies cellular proliferation and migration that effect repair of injured mucosal and vascular endothelial tissues. To determine whether CD44 could play a role in recovery from acute ischemic renal injury, we characterized its renal expression and those of two of its ligands, hyaluronic acid and osteopontin. Although no expression is detectable in nonischemic kidneys, several mRNAs for CD44 are present within 1 day after injury. CD44 mRNA is expressed in proximal tubules undergoing repair. CD44 peptide is present in basal and lateral cell membranes. Hyaluronic acid is normally expressed in the interstitium of the renal papilla only. By 1 day postischemia, hyaluronic acid can be detected, in addition, in the interstitium surrounding regenerating tubules. Osteopontin, not normally expressed in the renal proximal tubule, is expressed in regenerating tubules by 3 days after induction of acute ischemic injury. Immunoreactive osteopontin peptide continues to be localized in those tubules still undergoing repair for as long as 7 days after the injury. Our data are consistent with a role for CD44-ligand interactions in the regenerating proximal tubule participating in the process of recovery after ischemic injury.

Acute Disease↗

PubMed2000

Inhibition of poly(ADP-ribose) polymerase attenuates ischemic renal injury in rats.

The enzyme, poly(ADP-ribose) polymerase (PARP), effects repair of DNA after ischemia-reperfusion (I/R) injury to cells in nerve and muscle tissue. However, its activation in severely damaged cells can lead to ATP depletion and death. We show that PARP expression is enhanced in damaged renal proximal tubules beginning at 6-12 h after I/R injury. Intraperitoneal administration of PARP inhibitors, benzamide or 3-amino benzamide, after I/R injury accelerates the recovery of normal renal function, as assessed by monitoring the levels of plasma creatinine and blood urea nitrogen during 6 days postischemia. PARP inhibition leads to increased cell proliferation at 1 day postinjury as assessed by proliferating cell nuclear antigen and improves the histopathological appearance of kidneys examined at 7 days postinjury. Furthermore, inhibition of PARP increases levels of ATP measured at 24 h postischemia compared with those in vehicle-treated animals. Our data indicate that PARP activation is a part of the cascade of molecular events that occurs after I/R injury in the kidney. Although caution is advised, transient inhibition of PARP postischemia may constitute a novel therapy for acute renal failure.

Adenosine Triphosphate↗

PubMed2000

MR imaging of pancreatic masses.

MR imaging of the pancreas has evolved with better understanding of pathologic and radiologic correlation and with continued improvement in rapid-acquisition breath-hold or breathing-independent MR imaging techniques. MR imaging should be considered essential in the evaluation of pancreatic disease and particularly for optimal presurgical detection, characterization, and staging of pancreatic masses.

Adenocarcinoma↗

PubMed1999

SfbII protein, a fibronectin binding surface protein of group A streptococci, is a serum opacity factor with high serotype-specific apolipoproteinase activity.

Serum opacity factor (SOF) is produced by group A streptococci belonging to certain M types. SOF cleaves the apolipoprotein component of the high density lipoprotein fraction of serum rendering it insoluble which in turn leads to serum opacity. SfbII protein, a fibronectin binding surface protein cloned from group A streptococci, was obtained from a strain of M75. Here we show that this protein has a second functional domain responsible for SOF activity. The fibronectin binding region was located in the C-terminal end of the protein. Deletion analysis showed that the remainder of the protein was required for SOF activity. Sequence analysis of SfbII, when compared with the published sequence of SOF22, showed 99% identity with a difference of only four amino acids. In spite of this high homology, SOF from M75 was type-specific and antibody evoked specifically inhibited only SOF produced by M75. Antibodies found in human serum following natural infection also inhibited the SOF of SfbII in a type-specific manner. The results showed that the SfbII protein from M75 is SOF with a high serotype-specific enzyme activity.

Adhesins, Bacterial↗

PubMed1999

A significant increase in antimicrobial resistance among pneumococci causing invasive disease in New Zealand.

AIMS: To review the prevalence of antibiotic resistance and the distribution of capsular types among pneumococci from invasive disease in New Zealand from 1995 through 1997. METHOD: Pneumococci isolated from sterile sites that were referred to the Institute of Environmental Science and Research (ESR) were tested for antimicrobial susceptibility and capsular type. RESULTS: A total of 994 pneumococci were referred by 27 hospital and community laboratories. Almost 74% of the isolates were from patients aged < 15 years or > or = 60 years. The majority (88.2%) of the isolates were from blood cultures. In 1997, cefotaxime-resistant pneumococci were confirmed for the first time from invasive disease in New Zealand. Over the three years, 6.0% of the pneumococci were penicillin-nonsusceptible (MIC > or = 0.12 mg/L) and 3.7% were cefotaxime-nonsusceptible (MIC > or = 1 mg/L). Penicillin nonsusceptibility increased significantly from 1.9% in 1995 to 6.2% in 1996 and 9.9% in 1997. Similarly, cefotaxime nonsusceptibility increased from 0.6% in 1995 to 3.5% in 1996 and 6.9% in 1997. In descending order of frequency, the ten most common capsular types were 14, 19, 6, 9, 1, 4, 18, 7, 23, and 3. Eighty-three percent of the penicillin-nonsusceptible pneumococci belonged to serotypes 9V, 19A, 19F, 23F, 14 and 6B and 90% belonged to serotypes included in the 23-valent vaccine. CONCLUSIONS: The increasing prevalence of antimicrobial resistance among pneumococci highlights the need for continued surveillance and for effective measures to prevent pneumococcal infections.

Adolescent↗

PubMed1999

Percutaneous transluminal angioplasty of infrainguinal vessels.

In the last decade, percutaneous angioplasty (PTA) has been used with increasing frequency to treat infrainguinal atherosclerotic lesions. In hopes of better delineating the role of PTA, we undertook a retrospective analysis of infrainguinal PTA in one hospital over a 7-year period. The charts of all patients receiving infrainguinal PTA from 1989 to 1996 were reviewed. Demographics, site and type of lesion, and results of treatment were recorded. Survival curves were plotted using the Kaplan-Meier method following current Society of Vascular Surgery/International Society for Cardiovascular Surgery (SVS/ISCVS) guidelines. Differences in times to first failure were tested using the log rank method. Failures were documented by duplex ultrasound. All patients requiring repeat intervention underwent contrast angiography. In selected patients with stenotic lesions <3 cm, infrainguinal PTA may be an appropriate initial treatment modality. However, 5-year patency rates are significantly lower than those achieved by saphenous vein grafting. The efficacy of the procedure is markedly decreased when used to treat arterial stenoses >3 cm in length as well as occlusions, and surgical revascularization may be a more appropriate initial therapeutic procedure.

Angioplasty, Balloon↗

PubMed1999

An emergency department-based pneumococcal vaccination program could save money and lives.

STUDY OBJECTIVE: Pneumococcal vaccination (PV) rates for eligible emergency department patients are less than 25%. This study determines the potential effect of an ED-based pneumococcal vaccination program in preventing pneumococcal bacteremia (PB) in high-risk patients. METHODS: In a retrospective observational study, hospital records of 188 consecutive adults (>/=18 years old) with PB were reviewed to determine how many were treated in the ED from 1 to 72 months before their admission for bacteremia. Potential cost savings and mortality reductions from an ED-based PV program were calculated assuming PV prevents 65% of bacteremic episodes. A retrospective review of 10,650 ED charts determined the percentage of patients with PV indications and the relative frequency of indications. RESULTS: One hundred four (55%) of the 188 patients with PB were seen in the ED less than or equal to 72 months before their admission for PB, and 91 (88%) of the 104 had indications for PV. These 91 patients had been evaluated in the ED an average of 3.4 times per patient during this 72-month period. Nine patients (10%) died before discharge. Mean hospital stay for the 82 survivors was 11.2 days. Of 10,650 ED charts reviewed, 2,011 (19%) had documented PV indications. Most prevalent PV indications were age 65 years or older (851 patients, 42%), diabetes mellitus (697, 35%), malignancy (248, 12%), chronic renal failure (228, 11%), and immunosuppression (221, 11%). Estimated cost savings ranged from $168,940 to $427,380. CONCLUSION: ED-based PV programs would result in considerable cost savings and decreased mortality.

Academic Medical Centers↗

PubMed1999

Spontaneous pyopneumopericardium.

A previously healthy 42-year-old man presented to the emergency department with progressive weakness, lightheadedness, nausea, and lower extremity edema. Evaluation revealed hypotension, pulsus paradoxus, leukocytosis, hepatic and renal dysfunction, and an air-fluid level in the mediastinum. Emergency department ultrasound confirmed the presence of a large pericardial fluid collection. The patient was admitted to the medical intensive care unit with a diagnosis of pyopneumopericardium for emergent pericardiocentesis.

Adult↗

PubMed1998

New Zealand epidemic of meningococcal disease identified by a strain with phenotype B:4:P1.4.

New Zealand is experiencing an epidemic of serogroup B meningococcal disease, which has taken the rate of disease from an average of 1.5/100,000 population in the preepidemic years of 1989 and 1990 to 14.0/100,000 in 1996. Sterile-site isolates of Neisseria meningitidis from cases of invasive disease have been phenotypically characterized by serogrouping, serotyping, and serosubtyping, revealing the involvement of a strain with phenotype B:4:P1.4. Macrorestriction analysis using pulsed-field gel electrophoresis on 667 meningococci isolated from cases during the epidemic has identified the clonal relationship of meningococci expressing the PorA P1.4 antigen. Multilocus enzyme electrophoresis has shown the epidemic strain B:4:P1.4 to belong to lineage III. The recorded characteristics of New Zealand's epidemic are consistent with previous serogroup B epidemics in other parts of the world.

Adolescent↗

PubMed1998

Group A streptococcal Vir types are M-protein gene (emm) sequence type specific.

The M-protein genes (emm genes) of 103 separate impetiginous Streptococcus pyogenes isolates were sequenced and the sequence types were compared to the types obtained by Vir typing. Vir typing is based on restriction fragment length polymorphism (RFLP) analysis of a 4- to 7-kb pathogenicity island encoding emm and other virulence genes. By using both HaeIII and HinfI to generate RFLP profiles, complete concordance between Vir type and emm sequence type was found. Comparison of the emm sequences with those in GenBank revealed new sequence types sharing less than 90% identity with known types. Diversity in the emm sequence was generated by corrected frameshift mutations, point mutations, and small in-frame mutations.

Amino Acid Sequence↗

PubMed1998

Plasma leptin concentrations are only transiently increased in nephrectomized rats.

Leptin is an adipocyte-secreted hormone that has effects on appetite and energy expenditure. Several studies have shown that end-stage renal disease results in elevated plasma leptin concentrations and that the kidney is responsible for most of leptin elimination in rodents. Leptin metabolism was investigated in rats that underwent unilateral nephrectomy to experimentally limit renal elimination function. Within 4 h of nephrectomy, plasma leptin concentrations increased from 2.9 +/- 0.8 to 5.8 +/- 1.0 & microg/l but thereafter rapidly (<24 h) decreased to prenephrectomy concentrations, despite continued elevated plasma creatinine levels. Sham-operated rats maintained presurgical concentrations of leptin and creatinine throughout the experiment. Kinetic studies of 125I-labeled leptin elimination showed that fractional catabolic rates and half-lives of leptin in circulation were similar at 48 h in nephrectomized and sham-operated rats, suggesting that production of leptin was unchanged after nephrectomy. Excretion of 125I derived from leptin in urine of nephrectomized rats was similar to that of sham-operated rats, and residual radioactivity was increased in the remaining kidneys excised from nephrectomized rats. These results demonstrate that 1) leptin concentrations are quickly restored to presurgical levels in nephrectomized rats, and 2) it is leptin elimination, not leptin production, that compensates to maintain leptin concentrations. Rapid metabolic adaptation of remaining renal tissue may explain the restoration of normal leptin elimination in nephrectomized rats.

Animals↗

PubMed1998

Extracellular matrix-related genes in kidney after ischemic injury: potential role for TGF-beta in repair.

The renal expression of transforming growth factor-beta1 (TGF-beta1) is enhanced following induction of ischemic injury in rat. In cultured renal cells, TGF-beta stimulates the synthesis of extracellular matrix. To link TGF-beta1 expression with the regulation of extracellular matrix postischemia, we characterized the expression of several genes known to regulate extracellular matrix synthesis at various times during recovery from acute ischemic renal injury in rat. Levels of mRNA for plasminogen activator inhibitor-1 (PAI-1), tissue inhibitor of metalloprotease-1 (TIMP-1), alpha1(IV) collagen, and fibronectin-EIIIA (FN-EIIIA) mRNAs were significantly enhanced in kidneys within 12 h to 3 days after injury and remained elevated at 7-28 days postischemia relative to levels in kidneys of sham-operated controls. PAI-1 mRNA and peptide were localized in regenerating proximal tubules at 3 and 7 days postischemic injury. alpha1(IV) Collagen and FN-EIIIA mRNAs were expressed primarily in regenerating proximal tubule cells. Immunoreactivity for FN-EIIIA was enhanced in the tubular basement membrane (TBM) of regenerating proximal tubules, and alpha1(IV) collagen immunoreactivity was detected in thickened tubulointerstitial spaces. In contrast, TIMP-1 immunoreactivity was enhanced in distal nephron structures postischemia. Immunoneutralization of TGF-beta in vivo attenuated the increases in FN-EIIIA, alpha1(IV) collagen, PAI-1, and TIMP-1 mRNAs by 52%, 73%, 43%, and 27%, respectively. These data are consistent with TGF-beta expression postischemic injury participating in renal regeneration of extracellular matrix homeostasis in the proximal TBM.

Animals↗

PubMed1998

Videotape increases parent knowledge about poliovirus vaccines and choices of polio vaccination schedules.

OBJECTIVE: To study the effect of an educational videotape about poliovirus vaccines and choices of schedules for parents/guardians of children starting the polio vaccination series. DESIGN: Prospective, randomized trial comparing two educational interventions. SETTING: Five pediatric offices (two university-based, two health maintenance organization staff models, and one private practice) and a local health department immunization clinic in the greater Lansing, MI, area. PARTICIPANTS: A total of 287 parents/guardians of 2- to 3-month-olds presenting for well-child care and due for the first set of immunizations including poliovirus vaccine. INTERVENTIONS: Parents/guardians were randomized to read the vaccine information statement (VIS) alone or to read the VIS and view a 15-minute videotape about polio vaccination and choices of schedules produced by Michigan State University. The intervention groups were similar by race/ethnicity, education, and relationship to the child. OUTCOME MEASURES: Change in knowledge about the risk of poliomyelitis in the United States, transmission of poliomyelitis, characteristics of the two poliovirus vaccines, and choices of polio vaccination schedules; and parent opinion on effectiveness of the interventions, as measured by pre- and postintervention questionnaires. RESULTS: Both interventions resulted in increased test scores of knowledge. However, videotape viewers scored significantly higher on their posttest compared with parents/guardians assigned to VIS only. This significant increase was noted across all practice types, two of three major racial/ethnic groups, and educational levels. (The increase for Hispanic parents/guardians approached significance). Reading the VIS did not improve posttest scores for videotape viewers. Reading the VIS did improve posttest scores for those assigned to VIS only, but these scores still were not as high as for videotape viewers who did not read the VIS. CONCLUSIONS: This study demonstrated that a complicated discussion of risks/benefits of two vaccines and their schedules of administration could be communicated effectively via a videotaped presentation. In addition, the videotape was more effective than VIS alone in increasing short-term knowledge, regardless of practice type, race/ethnicity, or educational level. As immunization schedules increase in complexity and parents are asked to make more choices, videotaped information may be a better method to achieve the goal of truly informed consent.

Adult↗

PubMed1998

Quantitative evaluation of pork adulteration in raw ground beef by radial immunodiffusion and enzyme-linked immunosorbent assay.

Quantitative estimates are important to establish whether pork adulteration in ground beef is accidental or intentional. A standard agar gel radial immunodiffusion (RID) test using forensic-grade antiserum to porcine albumin and an enzyme-linked immunosorbent assay (ELISA) using forensic-grade anti-porcine glycoprotein immunoglobulin were used to determine from 1 to 75% raw pork in raw ground beef. The RID test, which incorporated 1.5% anti-pork serum in 1% immunodiffusion agar, formed precipitin rings with pork albumin in agar wells. A linear standard curve was obtained by plotting the diffusion area against standard pork concentrations ranging from 0 to 80%. For the ELISA the endpoint optical density increased linearly versus log % pork between 0.0625% and 2% pork. In spiked samples, the RID test had a detection limit of 3 to 5%, a coefficient of variation (CV) of 22%, and a recovery of 105%. The ELISA had a detection limit of 1%, a CV of 18%, and a recovery of 114%. The mean recovery from the spiked samples by the ELISA and RID test was not significantly different (P > 0.05) from the known sample amounts. Quantitation by RID of 28 ground beef samples (27 of which were DTEK ELISA-positive for pork adulteration) revealed a wide range of pork content, with values as high as 48%.

Animals↗

PubMed1997

Inhibition of IL-8 gene expression in Caco-2 cells by compounds which induce histone hyperacetylation.

Ulcerative colitis, an idiopathic inflammatory disease of the colonic mucosa, can be effectively treated by enemas containing short chain fatty acids (SCFA) such as butyrate, propionate, and acetate. The molecular mechanisms that lead to this response have not been well characterized. It is well known that intestinal inflammation leads to an alteration in patterns of epithelial differentiation with an increase in epithelial proliferation and an expansion of cell populations in an undifferentiated state. SCFAs such as butyrate are capable of inhibiting cell proliferation and inducing a differentiated phenotype in vitro. The Caco-2 colon cancer cell line was used to study the effect of SCFAs and the process of cellular differentiation on the expression of the pro-inflammatory cytokine, interleukin 8 (IL-8). SCFAs and trichostatin A, structurally unrelated compounds which both induce histone hyperacetylation, both led to a dose-dependent inhibition of IL-8 gene expression. Furthermore, spontaneous differentiation of Caco-2 cells by growth to a post-confluent state also inhibited the expression of IL-8. A possible mechanism by which SCFAs may be effective in the treatment of ulcerative colitis may be through their ability to increase histone acetylation states and inhibit the production of pro-inflammatory substances by the intestinal epithelium.

Acetylation↗

PubMed1997

Whole body leptin kinetics and renal metabolism in vivo.

Leptin metabolism was investigated in male Sprague-Dawley rats by use of 125I-labeled leptin plasma kinetic and arteriovenous balance studies. When conscious rats received bolus venous injections of 125I-leptin, intact (precipitable) leptin quickly disappeared from circulation in a biexponential manner during the 2-h experimental period. After substantial delay, most of the injected radioactivity appeared in the urine. The data were described by a two-compartment model, which postulated that plasma leptin exchanged with a nonplasma pool and that all of the tracer cleared from plasma appeared in urine or in a degraded form in plasma. The half-life of leptin was 9.4 +/- 3.0 min, and the leptin production rate was 3.6 +/- 1.2 ng 100 g fat-1.min-1. The left kidney extracted 21 +/- 1.5% of intact arterial 125I-leptin 5 min after femoral venous injection. Endogenous arterial leptin was reduced 21 +/- 8 and 18 +/- 12%, respectively, in simultaneously sampled left and right renal veins. Renal elimination appears to be the major elimination mechanism for leptin in normal rats, and the kinetic studies suggest that uptake of leptin by renal tissue rather than glomerular filtration is the predominant elimination mechanism.

Adipose Tissue↗