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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 163 records · Page 9Linked to original sources
PubMed1999

Computerized method to measure glare and contrast sensitivity in cataract patients.

PURPOSE: To evaluate computerized methods for measuring glare sensitivity and visual acuity at 3 contrast levels in cataract patients. SETTING: St. Erik's Eye Hospital, Stockholm, Sweden. METHODS: In a prospective study, 25 consecutive cataract patients meeting the inclusion criteria were examined before and 12 weeks after cataract surgery. Measured were glare sensitivity and visual acuity at 3 contrast levels using the Opthimus Y-VA Contrast Sensitivity Test and Glare Test. RESULTS: Preoperatively, all patients had impaired values compared with those in a group of age-matched normal volunteers (control group). Postoperatively, median values were similar to those in the age-matched control group in all parameters except glare sensitivity, which was significantly higher in the pseudophakic group (P = .03). Correlation coefficients between preoperative visual acuity and contrast sensitivity at 90%, 25%, and 10% were 0.50 (P = .01), 0.53 (P = .006), and 0.45 (P = .02), respectively, and between preoperative visual acuity and preoperative glare difference, 0.45 (P = .02). A significant correlation was found between age and visual acuity in the control group at all contrast levels: 90% (r = 0.61, P = .0018), 25% (r = 0.52, P = .01), and 10% (r = 0.42, P = .04). Median differences between Y-VA examinations (repeatability) were 0 LogMAR except between examinations 1 and 2 at the 25% contrast level, where it was 0.3 LogMAR. CONCLUSION: The Ophthimus Y-VA Test and Glare Test were useful in the preoperative evaluation of patients with cataract and mild to moderate visual impairment.

Adult↗
PubMed1999

Temporal and spatial control of the Sycp1 gene transcription in the mouse meiosis: regulatory elements active in the male are not sufficient for expression in the female gonad.

Transcription controls active at the initial stages of meiosis are clearly key elements in the regulation of germinal differentiation. Transcription of the Sycp1 gene (synaptonemal complex protein 1) starts as early as the leptotene and zygotene stages. Constructs with Sycp1 5' upstream sequences directed the expression of reporter genes to pachytene spermatocytes in transgenic mice. A short fragment encompassing the transcription start (n.t. -54 to +102) was sufficient for stage-specific expression in the adult male and for temporal regulation during development. Upstream enhancer element(s) quantitatively regulating expression were localized in the region between -54 and -260. The gene is normally expressed both in the male and female gonads, but none of the promoter sequences active in the testis allowed the expression of reporter genes during meiosis in the ovary.

Animals↗
PubMed1999

Effects of the type of holds and movement amplitude on postural control associated with a climbing task.

The aim of the present work was to characterize the modifications of the postural adjustments during a climbing task as a function of postural and/or movement constraints. The variations of the horizontal and vertical forces and momentum were analyzed for different movement amplitudes and types of holds. The results show that the horizontal momentum is influenced by all experimental conditions before the onset of movement. By contrast, the vertical momentum is only influenced by the amplitude of the movement, after its onset. These results confirm the hypothesis of a dual function of the anticipatory postural adjustments. The horizontal momentum is mainly involved in the control of equilibrium. The vertical momentum contributes to the movement initiation.

Adolescent↗
PubMed1999

A biomechanical study of equilibrium in sport rock climbing.

One of the main objectives of the experiment reported in this article was to analyze the arrangement of the forces applied to the holds accompanying a voluntary right foot release in the hanging rock climber. The three dimensional reaction forces applied to the holds were measured using four holds equipped with strain gauges. The force arrangement after the release consisted of a tripedal stance on the three remaining holds for the vertical forces, and of a bipedal stance on two laterally opposite holds (left foot and left holds) for the horizontal forces. The general significance of the results was analyzed with respect to the mechanism of static equilibrium. However, before conclusions can be drawn, other climbing movements and positions must be analyzed.

Adult↗
PubMed1999

Effects of calcitonin on animal and in vitro models of skeletal metabolism.

During the 40 years since its discovery, calcitonin (CT) has been regarded primarily as an inhibitor of bone resorption and its therapeutic applications have been based on this property. A significant body of literature also indicates additional anabolic effects in animal and in vitro models. In a variety of bone loss histomorphometric models in the rat, CT, especially the salmon species, prevents or retards bone loss. In other species, similar results have been obtained, except in the beagle given human CT, in which a recent study reported increased bone resorption and bone loss. Consonant with the histomorphometric effects in several different species, bone mass (density) measured by a variety of methods increases, reversing the bone loss induced by the model. In related studies of mechanical properties, bone strength is increased by CT except in the beagle study which utilized human CT. In other species, experimentally induced fractures show either accelerated healing or heal normally, and there is no effect of CT to impair healing. Finally, studies of bone formation/mineralization strongly suggest an anabolic effect on cartilage formation, bone matrix synthetic activity, and bone growth. These animal effects are reflected by recent fracture prevention studies in humans. If its anabolic effects are ultimately found to be separable and additive to CT's basic action to inhibit bone resorption, new approaches to osteoporosis prevention, and possibly other treatment situations such as cartilage regeneration, may evolve using novel CT-like molecules.

Animals↗
PubMed1999

Identification of oral Actinomyces species using DNA probes.

Oral Actinomyces comprise a major segment of both the supra- and subgingival microbiota; however, little is known about the distribution of individual species in different sites or clinical conditions. The purpose of the present investigation was to develop DNA probes for suggested species and genotypes of oral Actinomyces. Whole genomic DNA probes to 12 human oral species and/or serotypes were labeled with digoxigenin and used to seek cross-reactions among the taxa using the checkerboard DNA-DNA hybridization assay. The Actinomyces formed three distinct groups: 1) Actinomyces georgiae, Actinomyces meyeri and Actinomyces odontolyticus serotypes I and II; 2) Actinomyces viscosus and Actinomyces naeslundii serotypes I, II, III and WVA 963; and 3) Actinomyces gerencseriae and Actinomyces israelii. Cross-reactions among taxa were detected and minimized by increasing the temperature of the post-hybridization high-stringency wash to 80 degrees C. Despite the elevation in high stringency wash temperature, cross-reactions among strains of the A. naeslundii/A. viscosus group persisted. Probes for two of the three currently recognized genospecies in this group were prepared by removing the DNA in common between cross-reacting species using subtraction hybridization and polymerase chain reaction. Nine species and genospecies could be clearly separated by a combination of whole genomic and subtraction hybridization probes and by increasing the high-stringency wash temperature. A total of 195 fresh isolates of Actinomyces were grouped in a blind study using DNA probes and separately by SDS-PAGE protein profiles. Concordance between the two methods was 97.3%. The probes and hybridization conditions were tested for their ability to detect the Actinomyces species and genospecies in samples of supragingival and subgingival plaque from periodontitis subjects using checkerboard DNA-DNA hybridization. The probes detected the species in samples of supragingival and subgingival plaque. We concluded that whole genomic and subtraction hybridization DNA probes facilitate the detection and enumeration of species and genospecies of Actinomyces in plaque samples.

Actinomyces↗
PubMed1999

Clinical experience with latanoprost: a retrospective study of 153 patients.

PURPOSE: To evaluate the pressure-reducing effect of latanoprost in a clinical setting. PATIENTS AND METHODS: Data from 153 consecutive patients with open angle glaucoma receiving latanoprost were recorded at baseline (n=153), 2 weeks (n=151) and 8 to 12 months (n=89) after starting latanoprost treatment. In 82 patients (54%) latanoprost was added to ongoing treatment. Two patients terminated treatment because of side effects before the first follow-up examination. RESULTS: 56% (84/151) of the patients showed an intraocular pressure reduction of 20% or more after 2 weeks, regardless of baseline therapy. The difference between intraocular pressure before (24.4+/-5.8 mm Hg) and after 2 weeks of latanoprost treatment (19.9+/-6.9 mm Hg) in the total group (n=151) was highly significant (p<0.0001). The pressure reduction was significantly correlated with the pretreatment intraocular pressure level (r=0.48, p<0.0001). In the 89 patients who could be followed for 8 to 12 months no significant upward drift in mean intraocular pressure was observed, but in fourteen patients intraocular pressure increased with 5 mm Hg or more. Thirteen patients reported side effects, five of these discontinued the treatment. CONCLUSION: Latanoprost is obviously an efficient pressure reducing drug which can be used in glaucoma patients as an adjunct to any ongoing therapy with the expectation of clinically relevant intraocular pressure reduction in 45-71% of the patients.

Adrenergic beta-Antagonists↗
PubMed1999

Irreversible glomerular lesions induced by crystal precipitation in a renal transplant after foscarnet therapy for cytomegalovirus infection.

AIMS: Foscarnet is an antiviral agent used to treat cytomegalovirus infection in AIDS patients and in transplant recipients. In most cases, foscarnet induces reversible tubulo-interstitial lesions which can be avoided by correct hydration. We report the first case of crystal foscarnet precipitation within glomerular capillaries in a renal transplant. METHODS AND RESULTS: The recipient, a 49-year-old man, developed a nephrotic syndrome with haematuria and an acute renal failure after foscarnet therapy for cytomegalovirus (CMV) infection. The polarization examination of the first graft biopsy revealed the presence of birefringent crystals within glomeruli and tubules. Infrared analysis attested to the presence of trisodium foscarnet salts and mixed sodium calcium salts coloured by Von Kossa's reaction. A second biopsy showed glomerular sclerosis, interstitial fibrosis, tubular atrophy and crystal vanishing. Polymerase chain reaction (PCR) in situ applied to this biopsy confirmed the diagnosis of cytomegalovirus infection. CONCLUSIONS: These adverse effects might be the result of a toxic synergy between foscarnet and other drugs. In cases with crystalline precipitation, graft biopsy remains the best mean of diagnosis and follow-up of glomerular damage.

Biopsy↗
PubMed1999

The detection of enzyme A of Yersinia enterocolitica by a disc diffusion method.

Yersinia enterocolitica has been described as expressing two types of chromosomal beta-lactamase, the broad spectrum enzyme A and the inducible cephalosporinase enzyme B. Nevertheless, not all Y. enterocolitica strains express both enzyme A and enzyme B; Y. enterocolitica strains of the less commonly isolated biotype 2, serotype O:5 (27) lack the enzyme A. Also, no other members of the Enterobacteriaceae have been demonstrated to produce enzyme A. Detection of this enzyme could therefore be a useful laboratory tool in distinguishing common pathogenic strains of Y. enterocolitica from other Enterobacteriaceae. A simple test by disc diffusion on agar for the recognition of enzyme A expression in Y. enterocolitica was evaluated. The test was based on the resistance to ticarcillin conferred by enzyme A and the highly effective inhibition of this enzyme by clavulanic acid. A typical additional zone of inhibition between the zones of inhibition around a ticarcillin 75 micrograms disc and an amoxycillin/clavulanate 3 micrograms disc was indicative of the presence of enzyme A. By contrast, a large zone of inhibition around the ticarcillin disc without an additional zone of inhibition, reflected the absence of enzyme A.

Agar↗
PubMed1999

Tryptophan ingestion by pregnant rats induces pituitary and mammary tumours in the adult female offspring.

The present study was designed to evaluate the long-term consequences of tryptophan treatment on the central serotonergic activity in the female offspring of rats, and particularly on serotonin-controlled hormone release. During the second half of gestation, tryptophan (200 mg/kg/day) was given daily by stomach intubation to pregnant rats and the brain concentrations of serotonin and 5-hydroxyindole acetic acid and the plasma concentrations of prolactin, progesterone, oestradiol and luteinizing hormone were quantified in the adult female offspring. The offspring showed an increase in hypothalamic serotonin and serum progesterone and prolactin. In addition, maternal ingestion of tryptophan induced a marked rise in 665-day-old offspring in the incidence of both pituitary prolactinomas (62%) and mammary adenomas (49%). Present data suggest that tryptophan regulates serotonergic differentiation during early development. A transitory modification of the tryptophan concentration in the fetal brain induces a permanent increase in hypothalamic serotonin level and, in addition to modifying the release of prolactin, increases the incidence of tumours in the hypophysis and mammary gland.

Animals↗
PubMed1999

Panniculitis mimicking lupus erythematosus profundus: a new histopathologic finding in malignant atrophic papulosis (Degos disease).

We present the case of a 57-year-old woman with a 1-year history of a cutaneous eruption clinically and histopathologically characteristic of Degos disease. In one of the two cutaneous biopsy specimens taken from the trunk lesions, the histopathology consisted of necrosis and sclerosis of the subcutaneous lobules, a finding that to our knowledge has not been previously described in the cutaneous lesions of Degos disease. Two months after cutaneous biopsies were taken, the patient developed ptosis and an episode of acute abdominal pain; intestinal perforation and many characteristic lesions of visceral Degos disease involving the entire small bowel were noted at laparotomy.

Complement C3↗
PubMed1999

Postconcussive symptoms in children with mild closed head injuries.

OBJECTIVE: To examine the incidence and neuropsychological, behavioral, and neuroimaging correlates of postconcussive symptoms (PCS) in children with mild closed head injuries (CHI). DESIGN: 26 Children with mild CHI and 8 of their uninjured siblings, from 8 to 15 years old, were recruited prospectively and assessed at baseline (ie, within 7 days of injury) and at 3 months postinjury. Parents rated PCS, motivation and affective lability, and behavioral adjustment. Baseline ratings assessed premorbid functioning retrospectively, and follow-up ratings assessed postinjury status. On both occasions, children completed neuropsychological testing, and those with mild CHI also underwent magnetic resonance imaging (MRI). RESULTS: Children with mild CHI did not differ from siblings in baseline ratings of premorbid PCS but displayed higher ratings on several PCS at 3 months postinjury. Thirty-five percent of children with mild CHI showed increases in PCS, compared with baseline premorbid ratings, but none of the siblings did so. Children with mild CHI whose PCS increased from premorbid levels showed poorer neuropsychological functioning at baseline than did children whose PCS did not increase, although the differences had partially resolved by 3 months. They also displayed decreased motivation over time. Their behavioral adjustment was poorer and they had smaller white matter volumes on MRI, but the latter differences were present at baseline and did not change over time, suggesting that they existed prior to the injury. CONCLUSION: Postinjury increases in PCS occur in a sizable minority of children with mild CHI and more often than among uninjured siblings. Increases in PCS following mild CHI are associated with premorbid neurological and psychosocial vulnerability, but also with postinjury decrements in neuropsychological and neurobehavioral functioning.

Adaptation, Psychological↗
PubMed1999

Compliance with universal precautions in correctional health care facilities.

There were three main objectives of this cross-sectional study of Maryland State correctional health care workers. The first was to evaluate compliance with work practices designed to minimize exposure to blood and body fluids; the second, to identify correlates of compliance with universal precautions (UPs); and the third was to determine the relationship, if any, between compliance and exposures. Of 216 responding health care workers, 34% reported overall compliance across all 15 items on a compliance scale. Rates for specific items were particularly low for use of certain types of personal protective equipment, such as protective eyewear (53.5%), face mask (47.2%) and protective clothing (33.9%). Compliance rates were highest for glove use (93.2%) waste disposal (89.8%), and sharps disposal (80.8%). Compliance rates were generally not associated with demographic factors, except for age; younger workers were more likely to be compliant with safe work practices than were older workers (P < 0.05). Compliance was positively associated with several work-related variables, including perceived safety climate (i.e., management's commitment to infection control and the overall safety program) and job satisfaction, and was found to be inversely associated with security-related work constraints, job/task factors, adverse working conditions, workplace discrimination, and perceived work stress. Bloodborne exposures were not uncommon; 13.8% of all respondents had at least one bloodborne exposure within the previous 6 months, and compliance was inversely related to blood and body fluid exposures. This study identified several potentially modifiable correlates of compliance, including factors unique to the correctional setting. Infection-control interventional strategies specifically tailored to these health care workers may therefore be most effective in reducing the risk of bloodborne exposures.

Adult↗
PubMed1999

Pharmacokinetics of intravenous dolasetron in cancer patients receiving high-dose cisplatin-containing chemotherapy.

Dolasetron mesylate (MDL 73,147, Anzemet, Hoechst Marion Roussel, Kansas City, MO) is a 5-HT ( 3 ) receptor antagonist undergoing clinical evaluation as an antiemetic agent. Dolasetron is rapidly metabolized to form hydrodolasetron (MDL 74,156). The pharmacokinetics of hydrodolasetron were studied after administration of a single intravenous infusion of 0.6 mg/kg (group I) or 1.8 mg/kg (group II) in 21 cancer patients participating in a randomized, double-blind, parallel-group, multicenter trial of the drug in patients receiving their first course of high-dose (>/=75 mg/m ( 2 ) ) cisplatin-containing chemotherapy. The intent of this study was to obtain preliminary data on the pharmacokinetics of the active metabolite, hydrodolasetron, in cancer patients. The reduced metabolite, hydrodolasetron, was formed rapidly with peak plasma concentrations (group I, mean = 128.6 ng/mL; group II, mean = 505.3 ng/mL) occurring at or shortly after the end of the infusion. Plasma concentrations of hydrodolasetron remained quantifiable for up to 24 hours. Increases in peak plasma concentrations and AUC of hydrodolasetron were proportional to dose, suggesting linear pharmacokinetics over this dose range. Apparent clearance, apparent volume of distribution, elimination rate, and terminal elimination half-life of the reduced metabolite were similar at both doses. The results support a pharmacokinetic basis for the prolonged duration of antiemetic efficacy after a single intravenous dose.

Aged↗
PubMed1999

Development of a new experimental model of penicillin-resistant Streptococcus pneumoniae pneumonia and amoxicillin treatment by reproducing human pharmacokinetics.

The increase of penicillin-resistant Streptococcus pneumoniae (PRSP) pneumonia results in a greater risk of antibiotic treatment failure. In vitro data are not sufficient predictors of clinical efficacy, and animal models may be insufficiently contributive, since they often use immunocompromised animals and do not always respect the human pharmacokinetics of antibiotics. We developed an experimental PRSP pneumonia model in immunocompetent rabbits, by using intrabronchial instillation of PRSP (MIC = 4 mg/liter), without any adjuvant. This reproducible model was used to assess amoxicillin efficacy by reproducing human serum pharmacokinetics following 1-g oral or intravenous administrations of amoxicillin every 8 h. Evaluation was performed by using clinical, CT scan, macroscopic, histopathologic, and microbiological criteria. Experimental pneumonia in untreated rabbits was similar to untreated severe human bacteremic untreated pneumonia; in both rabbits and humans, (i) cumulative survival was close to 50%, (ii) red or gray lung congestion and pleuritis were observed, and (iii) lung and spleen concentrations reached 5 and 4 log(10) CFU/g. A 48-h treatment resulted in a significant bacterial clearance in the lungs (1.53 versus 5.07 log(10) CFU/ml, P < 0.001) and spleen (1.00 versus 4.40 log(10) CFU/ml, P < 10(-6)) and a significant decrease in mortality (0% versus 50%, P = 0.02) in treated versus untreated rabbits. No difference was observed on macroscopic and histopathologic lesions between treated and untreated rabbits (P = 0.36 and 0.78, respectively). Similar results were obtained by using a fully penicillin-susceptible S. pneumoniae strain (MIC = 0.01 mg/liter). Our findings suggest that (i) this new model can be contributive in the evaluation of antibacterial agents and (ii) 1 g of amoxicillin three times a day may be sufficient to treat PRSP pneumonia in immunocompetent humans.

Amoxicillin↗
PubMed1999

Glycosyltransferase domain of penicillin-binding protein 2a from Streptococcus pneumoniae is membrane associated.

Penicillin-binding proteins (PBPs) are bacterial cytoplasmic membrane proteins that catalyze the final steps of the peptidoglycan synthesis. Resistance to beta-lactams in Streptococcus pneumoniae is caused by low-affinity PBPs. S. pneumoniae PBP 2a belongs to the class A high-molecular-mass PBPs having both glycosyltransferase (GT) and transpeptide (TP) activities. Structural and functional studies of both domains are required to unravel the mechanisms of resistance, a prerequisite for the development of novel antibiotics. The extracellular region of S. pneumoniae PBP 2a has been expressed (PBP 2a*) in Escherichia coli as a glutathione S-transferase fusion protein. The acylation kinetic parameters of PBP 2a* for beta-lactams were determined by stopped-flow fluorometry. The acylation efficiency toward benzylpenicillin was much lower than that toward cefotaxime, a result suggesting that PBP 2a participates in resistance to cefotaxime and other beta-lactams, but not in resistance to benzylpenicillin. The TP domain was purified following limited proteolysis. PBP 2a* required detergents for solubility and interacted with lipid vesicles, while the TP domain was water soluble. We propose that PBP 2a* interacts with the cytoplasmic membrane in a region distinct from its transmembrane anchor region, which is located between Lys 78 and Ser 156 of the GT domain.

Amino Acid Sequence↗