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Biomedical subjects

S Martin

Publications and source records attributed to S Martin.

At least 721 records · Page 40Linked to original sources
PubMed1971

Initiation of staphylococcal growth in laboratory media.

The effects of pH and NaCl concentration on the probability of aerobic growth initiation in Brain Heart Infusion broth at 30 C by five staphylococcal strains producing enterotoxins A, B, C, and D were studied in a factorial design experiment. Statistical analysis of the data indicated: (i) significant effects of pH, NaCl, and strain on the probability of growth; (ii) diverse effects of NaCl with various pH levels and strains; (iii) essentially a linear relationship between NaCl concentration and probability of growth initiation when data for all strains were pooled; (iv) the relationship between NaCl concentration and probability of growth initiation varies from linear to sigmoid, depending on the pH of the broth, when the statistically untreated (raw) data are plotted for each strain. Equations were derived which relate the decimal reductions of the number of cells of a staphylococcal population to the concentration of NaCl and pH of broth to which the population was exposed. From the equations, the probability that one cell is capable of initiating growth can be calculated. The impact of these types of studies on the development of realistic staphylococcal standards in foods is discussed.

Culture Media↗
PubMedDate not supplied

Non-specific viral infections as possible synchronising events of the manifestation of type 1 diabetes.

Four cases of simultaneous manifestation of Type 1 diabetes in two members of the same household are reported. In all cases, a flu-like infection preceded diabetes onset. Surprisingly, despite simultaneous development of insulin dependency, insulin requirements were strikingly different at 3 months in all cases. These observations suggest that increased insulin resistance during infection may cause insulin deficiency in individuals with widely varying residual beta cell activity.

Diabetes Mellitus, Type 1↗
PubMedDate not supplied

A phase 1a clinical trial of LYM-1 monoclonal antibody serotherapy in patients with refractory B cell malignancies.

Ten patients with refractory B cell lymphomas were treated with weekly intravenous infusions of escalating doses of murine monoclonal antibody (MoAb) LYM-1 over four weeks. LYM-1 is a recently developed IgG2a murine MoAb that recognizes a polymorphic HLA-Dr antigen on surfaces of normal and malignant B cells but does not bind to any other normal tissues. MoAb LYM-1 has several advantages for serotherapy, since the antigen it recognizes is not shed from the cell surface and does not modulate in response to MoAb therapy. Furthermore, in vitro studies have indicated significant anti-tumour activity against lymphoma cell lines. In the current trial, dose-dependent levels of free LYM-1 were detected in the serum of all patients, but penetration of extravascular tumour tissues was poor. No significant toxicity or human anti-mouse antibody responses were observed in any patient. Clinical responses were minor and appeared to correlate with the number of infiltrating T cells seen in the initial lymphoma specimens. LYM-1 appears to be well-tolerated and has demonstrated several potential advantages as a therapeutic agent in patients with lymphoma. The mechanism of anti-tumour effect and plans for further clinical studies are discussed.

Adult↗
PubMedDate not supplied

Realtime sonographic diagnosis of fetal dysplastic kidney.

A case of unilateral renal dysplasia was diagnosed in utero using realtime scanning. The diagnosis was confirmed neonatally and the affected kidney was surgically removed. Pathologic findings were consistent with the features of this malformation. The echographic characteristics of renal dysplasia and the differential diagnosis are described. The potential uses of ultrasonography in the diagnosis and follow-up of pregnancies associated with or at risk of renal malformations are discussed.

Adult↗
PubMedDate not supplied

Thoracoscopic repair of instrumental perforation of the oesophagus: first report.

BACKGROUND: Perforation of the oesophagus is a life-threatening condition requiring early recognition and repair to prevent mediastinitis and death. Primary closure with mediastinal drainage is recognised as the treatment of choice for patients presenting within 24 hours. Many are frail, however, and unsuitable for major surgery. AIM: To report the first case of thoracoscopic repair of the oesophagus for oesophageal perforation following instrumentation. METHODS: Flexible endoscopy revealed a 10cm perforation in the right lower oesophagus. With the gastroscope in the oesophagus, four thoracoports were introduced. Using suction and irrigation, the pleural cavity was suctioned free of debris and a 10cm longitudinal tear of the right lateral aspect of the oesophagus was repaired using interrupted polyglactin sutures through all layers. RESULTS: The patient tolerated the procedure well and made an uncomplicated recovery. CONCLUSION: The uncomplicated recovery of this frail patient without need for blood transfusions or assisted ventilation supports the notion that the thoracoscopic approach may have significant advantages. With increased experience and technical refinements there should be less reluctance to refer these patients for earlier definitive surgical repair.

Aged↗
PubMedDate not supplied

[Inhibition and resource capacity during normal aging: a confrontation of the dorsal-ventral and frontal models in a modified version of negative priming].

BACKGROUND: Over the past decades, cognitive psychology contribution to our understanding of aging relies on two major perspectives, focusing on the selective impact of age on either cognitive multiple-systems or global factors of cognition: slowing, working memory and inhibition. In the latter, reduction in inhibitory control during aging (in its access, deletion or restraint functions) is associated with poorer performance on a variety of tasks referring to memory, comprehension or language [Hasher, Zacks and May (16)]. The attractiveness of inhibition as an explanatory factor results in part in the absence of negative priming during aging. Negative priming refers to the slow down of latencies when individuals have to respond to recently ignored informations, compared to unrelated informations. The dissociation, between a preserved location negative priming and an absence of identity negative priming during aging, supports the dorsal-ventral model of inhibition which suggests that spatial and identity inhibition are supported by different and independent visual pathways. An alternative model, directly at odds, is that inhibitory mechanisms are supported by the frontal lobe. In this perspective, inhibition is not a central process responsible for the control of working memory contents, but an automatic and local mechanism whose triggering depends on controlled attention. Therefore, working memory drives efficient inhibition by sustaining task instructions and appropriate responses throughout task execution. This hypothesis is consistent with Houghton and Tipper's (17) architecture of selective attention. According to the authors, the presence or absence of automatic inhibition is very closely linked to a Match/Mismatch field whose function is to compare the present stimulus to an internal self-generated internal template. When an information fails to match the subject's current goals, the match/mismatch field causes an automatic inhibitory imbalance which reduces the to-be-ignored properties' responsiveness. In contrast, information matching subjects' goal is enhanced through an automatic excitatory imbalance. The accurate functioning of the Match/Mismatch field requires efficient executive functioning responsible for the uphold of goals and correct responses. In the case of negative priming, manipulating the efficiency of working memory is of interest as it should affect the triggering of slowing, ie, an indirect inhibitory deficit, when the task is resource demanding [Conwayet al. (6)]. Moreover, if inhibition, as reflected by negative priming, is mediated by individual resource capacity, then NP should disappear during aging only when individuals are engaged in a resource-demanding task. OBJECTIVES: To address this issue, we examine whether cognitive control load in a gender decision task contributed to the presence or absence of NP during aging. According to the dorsal-ventral model, task complexity should not have any impact on performance, since gender decision task relies on a conceptual analysis of information. In turn, the frontal model predicts that age differences in performance profile will only differ when individual resource capacity is overloaded. DESIGN OF THE STUDY: Sixty-four participants (32 young and 32 older adults) performed a gender categorisation task through two experiments. Trials involved two stimuli presented successively at the same location. A word served as a prime and a word as a target. Both prime and target could be male or female. When prime and target matched on gender, we talked about VALID pairs (or compatible). When prime and target mismatched on the manipulated features, we talked about INVALID pairs (or incompatible). Participants' task was to identify the gender of the target. They were explicitly instructed not to respond to primes but to read them silently. Our interest was in response latencies for valid versus invalid pairs. We manipulated task complexity by the absence (experiment 1) or presence (experiment 2) of a distractor during probe trials. RESULTS: For younger adults, primes presented before targets gave rise to behavioural costs when pairs were mapped to the same response compared to pairs that were mapped to opposite ones. This slowing, called Negative Compatibility Effect (NCE), was independent of the presence or absence of a distractor. NCE was reliable for the elderly patients only under condition of no interfering information during the probe trial: pattern of performance of older participants was identical to that of young adults (experiment 1). This effect disappeared as task complexity increased (experiment 2). DISCUSSION: This result suggests that NCE triggering is dependant on the amount of cognitive control engaged by the task, and therefore that the ability to inhibit irrelevant information is secondary to a general capacity of the working memory. CONCLUSION: The implications of our data are consistent with the level of processing account, as well as the recent neuroimaging contributions which suggest, for example, the involvement of the dorso-lateral prefrontal cortex (sensitive to aging) when task demands are high, and a ventro-lateral prefrontal implication when demands are low [see Eenshuistra et al. for a review (10)].

Adult↗