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Biomedical subjects

L Martin

Publications and source records attributed to L Martin.

At least 361 records · Page 20Linked to original sources
PubMed1993

The influence of field size and other treatment factors on pulmonary toxicity following hyperfractionated irradiation for inoperable non-small cell lung cancer (NSCLC)--analysis of a Radiation Therapy Oncology Group (RTOG) protocol.

PURPOSE: The risk of pulmonary toxicity, observed in an Radiation Therapy Oncology Group Phase I/II randomized dose escalation trial of hyperfractionated irradiation for nonsmall cell lung cancer, was analyzed with regard to custom vs. hand blocking and compliance to protocol specified treatment field parameters. MATERIALS AND METHODS: There were 832 evaluable cases analyzed. The protocol required field margins 2 cm beyond primary tumor and involved nodes. In 674, the field margins were considered "per protocol" or as having minor protocol variations. In 94, margins exceeded protocol specification ("excessive margin" group). In this group, the area (cm2) of the effective (blocked) field and the portion including lung was measured from simulator films with a computer scanning device. Based on size and location of the primary and nodal disease, "per protocol" fields were constructed and the area (cm2) of lung included beyond these margins was estimated. Patients from both groups who received less than 30 Gy to normal lung were excluded from analysis of pulmonary toxicity. RESULTS: Grade 1 acute lung toxicity was higher (p = .009) in the "excessive margin" group compared to the "per protocol" group, whereas late lung toxicity was not significantly different (p = .94). The risk of Grade 2 or greater acute toxicity increased as area of excess irradiated lung increased. Overall lung toxicity, defined as the greater of either acute or late toxicity, was evaluated by multivariate analysis, in relation to assigned dose, effective treated field area, and type of shielding. Overall maximum lung toxicity (> or = Grade 2) was significantly greater in the "excessive margin" group, when lung treated beyond protocol margins exceeded an area of 35 cm2, than in the "per protocol" group, but only when the effective treated field size was > or = 180 cm2 (68% vs. 37%; p = .02). This effect was independent of assigned total dose or type of shielding. CONCLUSION: For nonsmall cell lung cancer treated with hyperfractionated irradiation, the risk of overall pulmonary toxicity was increased for patients treated with field sizes in excess of protocol specified margins of tumor coverage in comparison to patients treated with protocol specified margins. This effect was seen only when the area of lung treated beyond protocol margins exceeded 35 cm2 and when the overall field size was below 180 cm2.

Carcinoma, Non-Small-Cell Lung↗
PubMed1993

Oxygenation of head and neck tumors.

BACKGROUND: Tumor hypoxia could play a role in the response to radiation therapy. Few data are available on oxygen tension (pO2) measurements in head and neck tumors. METHODS: The KIMOC-6650 Histograph (Eppendorf, Hamburg, Germany) was used to measure the oxygenation status of normal tissues and head and neck tumors in 20 patients. RESULTS: The median pO2 for normal tissues was 43 mmHg with very low pO2 values (2.0 mmHg or less) recorded in two patients. Low median pO2 levels (10 mmHg or less) were recorded in 2 of 5 primary tumors and in 11 of 15 metastatic lymphadenopathies, with very low values in 11 nodes. The median pO2 in tumors was lower than that of normal tissues in 12 of 15 patients with comparative measurements. Oxygen tension was recorded in three nodes after an evaluation of tissue density (by computed tomographic scanner); in two nodes, the mean and median pO2 values were lower in the hypodense areas than in isodense areas. The data for N2 and N3 nodes showed significantly more values below 2.0 mmHg as nodal size increased (P < 10(-4), by chi-square test). No systematic decrease in pO2 was recorded from the periphery to the center of the tumors. CONCLUSIONS: Very low pO2 values, corresponding to radiobiologic hypoxia, were found in most of these tumors. The prognostic value of these pO2 measurements in regard to treatment response remains to be demonstrated.

Adult↗
PubMed1993

An evaluation of mechanisms by which tolerance to organ-specific antigens is lost using a transgenic mouse model.

Patients with type I diabetes lose immunologic tolerance to beta cell Ag and produce anti-self (beta cell) antibodies. We have examined mechanisms by which this self tolerance is lost using transgenic mice in which islet cells express human CD4. These mice are immunologically tolerant to this human protein; the tolerance appears to be characterized by the presence of self reactive B cells and nonresponsive T cells. Autoantibodies can be induced by immunization with CD4 in CFA; this autoantibody response is accompanied by minor peri-islet inflammation but diabetes is not induced. Tolerance can also be broken by provision of an independent covalently linked T cell epitope. Although this mimic can lead to the appearance of an autoantibody response, the autoimmune response can not be maintained by the endogenous Ag. We have also demonstrated that an inflammatory lesion leading to death of the CD4-containing beta cells may not be sufficient to break tolerance. These results have implications for potential mechanisms relating to the appearance of autoantibodies in patients with type I diabetes.

Animals↗
PubMed1993

Effect of electrical stimulation training on the contractile characteristics of the triceps surae muscle.

This study aimed to assess the effects of training using electrical stimulation (ES) on the contractile characteristics of the triceps surae muscle. A selection of 12 subjects was divided into two groups (6 control, 6 experimental). The ES sessions were carried out using a stimulator. Flexible elastomer electrodes were used. The current used discharged pulses lasting 200 microseconds at 70 Hz. Contraction time was 5 s and rest time 15 s. The session lasted 10 min for each muscle. Training sessions were three times a week for 4 weeks. Biomechanical tests were performed using an isokinetic ergometer. Subjects performed plantar flexions of the ankle over a concentric range of movement at different angular velocities (60, 120, 180, 240, 300, 360 degrees.s-1) and held isometric contractions for 5 s at several ankle flexion angles (-30/-15/0/15 degrees-0 corresponded to foot flexion of 90 degrees relative to the leg axis). The force-velocity relationship was seen to shift evenly upwards under the influence of ES (P < 0.05). The increased force during the "after" test was greater (P < 0.05) for ankle angle positions of 15 degrees and -30 degrees, which demonstrated a link between the training angle and the gain in strength. No change was noted in the cross-sectional area of the muscle. The results showed that ES allowed the contractile qualities of muscle to be developed in isometric and dynamic conditions. Nervous mechanisms can account for most of these adaptations.

Adult↗
PubMed1993

Signet-ring cell adenocarcinoma of bladder.

Three cases of signet-ring cell adenocarcinoma of the bladder are presented: a primary vesical adenocarcinoma, a metastatic one, and a signet-ring cell adenocarcinoma of the urachus. A review of the literature found 69 additional reports of primary signet-ring cell adenocarcinoma, 20 of urachal signet-ring carcinoma, and 4 of the metastatic variety. The pathogenesis, clinical, and histologic findings, prognosis, and management are discussed.

Adenocarcinoma, Mucinous↗
PubMed1993

Changes in the oxygenation of head and neck tumors during carbogen breathing.

The oxygenation of head and neck tumors and changes during carbogen breathing were assessed in 20 patients. The median oxygen tension (pO2) for each patient was lower in tumors before breathing carbogen than in normal tissues. The median pooled pO2 of all the tumors was 20 mmHg; for normal tissue it was 60 mmHg. Low values (below 10 mmHg) were found in 4 patients for the normal tissue and in 18 patients for tumors. During carbogen breathing, the median (61 mmHg) pO2 readings for all tumors was higher than that recorded before carbogen breathing. The frequency of low (< 10 mmHg) pO2 values decreased with carbogen breathing in 11 patients; only 4 patients still exhibited very low values (< 2 mmHg). Maximal effect was obtained within 1-6 min of gas exposure. The pO2 stayed high under carbogen breathing in 15 out of 16 patients. Return to pre-carbogen levels of oxygenation occurred in 1 min after the end of gas exposure. These data suggest that carbogen breathing increases tumor oxygenation as assessed by polarography. The breathing time appears to be important for therapeutical use and should to be taken into consideration.

Adult↗
PubMed1993

Tissue and organ procurement in the emergency department setting.

A retrospective chart review of all emergency department (ED) deaths in patients younger than 65 years in seven area hospitals was performed for the calendar year of 1990. The number and percentage of families approached and consenting to tissue donation among the various EDs was compared and reasons for not approaching families were evaluated for their validity. Procurement rates between the years 1990 and 1991 were compared for two area hospitals, which made a specified (nonmedical) service responsible for tissue requests in 1991. There were 368 deaths, 255 of which were potential donors by acceptable criteria. Only 109 (43%) families were approached regarding tissue donation. The overall procurement rate was 12%. Suburban EDs had a higher approach and procurement rate than did urban EDs (49% vs 36%; P < .05 and 19% vs 5%; P < .01, respectively). Procurement rates for two hospitals that designated a specific procurement service in 1991 more than doubled (5% vs 11%; P = NS). Tissue procurement rates in EDs with procurement systems in place are low despite consent rates of those approached of 36%. The major contributing factor is the failure to request tissue from the families of eligible candidates even when there are no exclusion criteria met. Suburban EDs had a higher success rate than urban EDs.

Data Collection↗
PubMed1993

Recessive dystrophic epidermolysis bullosa--management of hand deformities.

Scarring in recessive epidermolysis bullosa results in disability through hand deformities. Surgical treatment is complicated by technical and anaesthesiological problems due to the fragility of the skin and mucosa. In its dystrophic form epidermolysis bullosa leads to pseudosyndactyly and finger and palm contracture resulting in a "closed hand". Surgical treatment consists of resecting the contractures and opening the inter-digit webs, the uncovered areas healing under a close tulle gras dressing. Our technique differs from techniques which have already been reported. The dressing is changed only once a week, reducing the number of anaesthetics and allowing the child to attend our Day Hospital. Healing is complete within five weeks. Prevention of recurrence avoids the necessity of further surgery before five years of age. Post-operative open-hand splinting is well tolerated, delaying further contracture. Surgery is undertaken sometimes under general anaesthesia but more often under regional anaesthesia. We report the results of our experience.

Child↗
PubMed1993

A comparison of laparoscopic and traditional appendectomy.

Forty-one serially performed laparoscopic appendectomies were compared to 41 randomly selected traditional open appendectomies performed during the same 18 month period. The average age and sex distribution of the two groups were similar. The pathological diagnoses of acute appendicitis and perforation were similar in both groups. The complication rates were not statistically different in the two groups. There were no complications unique to the laparoscopic group. The hospital stay was considerably shorter for patients undergoing laparoscopic appendectomy (p < .05). Statistical significance was found both in patients with and without perforation.

Adult↗
PubMed1993

Characterization of hemolytic bacteria in subgingival plaque.

Three-quarters of the patients with periodontal diseases surveyed in this study had one or more distinct types of hemolytic bacteria in their subgingival plaque. Twelve different species of bacteria were identified, belonging to five genera (Actinomyces, Streptococcus, Staphylococcus, Prevotella, and Actinobacillus). Nine hemolytic isolates, consisting of four Prevotella denticola strains, two Actinomyces naeslundii genospecies 2 strains, and one each of P. melaninogenica, Streptococcus constellatus, and A. naeslundii genospecies 1 strains were characterized. Incorporation of pronase into blood agar medium inhibited hemolysis by all of the isolates, suggesting a proteinaceous component for each of their hemolysins. With one exception, hemolysin production appeared to be regulated by the concentration of environmental iron: exogenous hemin was found to inhibit hemolysin production, and the iron scavenging compound, 2,2'- dipyridyl, was found to promote hemolysin production by all of the strains except for the S. constellatus isolate. Genomic libraries of each of the hemolytic plaque isolates were prepared in Escherichia coli using pBR322. Hemolytic clones were isolated on blood agar medium containing ampicillin at frequencies ranging from 1-6.7 x 10(-4). Extensive restriction mapping revealed regions of homology in the case of clones derived from three P. denticola strains isolated from the same subjects. Two of the P. denticola-derived clones were virtually identical throughout the entrety of their > 5 Kb inserts. The clone derived from the third strain showed good homology to the other two within a 1.3 Kb region, but the flanking DNA showed no homology even though all three P. denticola isolates were shown to be clonally related by ribotyping.(ABSTRACT TRUNCATED AT 250 WORDS)

Actinomyces↗
PubMed1993

Identification of a subset of patients with scleroderma with severe pulmonary and vascular disease by the presence of autoantibodies to centromere and histone.

OBJECTIVES: The role of autoantibodies in the investigation and management of rheumatic diseases is well recognised. The objective of this study was to determine the clinical significance of the co-occurrence of antibodies to centromere and histone in serum samples from patients investigated for systemic rheumatic diseases. METHODS: Serum samples from 1316 consecutive patients were screened for antinuclear antibodies and the clinical findings in patients with antibodies to centromere alone were compared with those with antibodies to both centromere and histone. RESULTS: Twenty six patients had antibodies to centromere. Fourteen patients had antibodies to centromere alone and 12 patients had antibodies to centromere and histone. Four of the 12 patients with antibodies to centromere and histone had diffuse scleroderma with severe pulmonary or vascular disease. CONCLUSIONS: A subset of patients with scleroderma with antibodies to centromere and histone has been identified retrospectively, who have severe pulmonary or vascular disease. It will be of interest to follow up the clinical course of other patients with scleroderma who have both antibodies for the development of pulmonary or vascular disease.

Adult↗
PubMed1993

Effect of photoperiod on the annual cycle of testis growth in a tropical mammal, the little red flying fox, Pteropus scapulatus.

Little red flying foxes (Pteropus scapulatus) are seasonal breeders: they mate in late spring/early summer, and young are born the following autumn. In captivity, males housed outdoors in a normal breeding colony in natural daylight showed a single cycle of testis growth and regression each year. During reproductive quiescence, testicular volume was approximately 2 cm3; recrudescence began soon after the winter solstice; testicular volume was maximum at approximately 6.5 cm3 at the spring equinox; and regression was complete by the end of summer. To test whether photoperiod entrains or synchronizes the cycle, groups of males were housed indoors, without females, at constant temperature, and artificial lighting was timed to either mimic naturally changing daylength or provide alternating 3-month periods of short (11 h light:13 h dark) or long (16 h light:8 h dark) days (two groups, three months out of phase with each other). During 18 months, the applied photoperiod protocol had no effect on the frequency of testicular cycles (which remained at one per year), the time course of recrudescence and regression (as described above for normal outdoor control males), or the completeness of growth and regression stages. These results suggest that male P. scapulatus are not reproductively photoresponsive.

Animals↗
PubMed1993

A facial variant of steatocystoma multiplex.

A case of steatocystoma multiplex confined to the face is reported. Review of the literature disclosed similar cases in this striking location. We therefore believe that this facial variant is a distinctive but less well known variant of steatocystoma multiplex. We review the relationship between steatocystoma multiplex and eruptive vellus hair cysts.

Adult↗
PubMed1992

Polyphosphoinositide hydrolysis and protein kinase C activation in guinea pig tracheal smooth muscle cells in culture by leukotriene D4 involve a pertussis toxin sensitive G-protein.

Leukotriene D4 (LTD4) at concentrations greater than 1 nM induced phosphatidylinositol bisphosphate (PIP2) hydrolysis and protein kinase C (PKC) activation in primary culture of airway smooth muscle cells. Within seconds of activation, an increase in inositol 1,4,5-trisphosphate (IP3) was observed reaching a maximum at 5 min. The level of IP3 decreased after 5 min and was followed by an increase in inositol 1,4-bisphosphate (IP2) and inositol 1-monophosphate (IP1). LTD4-induced PIP2 hydrolysis was inhibited by 1 h pretreatment of cells with 10 micrograms/ml of pertussis toxin (PTX). LTD4 activated both soluble and particulate forms of PKC by 2-3-fold. The LTD4-induced PKC activation was blocked by treatment of cells with PTX, suggesting the involvement of a PTX-sensitive G-protein. To assess the involvement of G(i) in smooth muscle cell receptor activation, the modulation of adenylyl cyclase activity was investigated. LTD4 did not stimulate cAMP formation in smooth muscle cells, and did not inhibit forskolin-induced cAMP formation. These data suggest that the LTD4 receptor in airway smooth muscle cells is coupled to a PTX-sensitive G-protein, possibly G(o).

Adenylate Cyclase Toxin↗
PubMed1992

Involvement of hypothalamic noradrenergic systems in the modulation of intestinal motility in rats.

Selective lesions of the noradrenergic systems of the paraventricular nucleus (PVN) of the hypothalamus with 6-hydroxydopamine (6-OHDA) lengthen the periodicity of the migrating myoelectric complex (MMC), an index of intestinal motility, in rats. These lengthening effects resemble those obtained after lesions of the locus coeruleus (LC), thus suggesting that noradrenergic terminals from LC to the PVN are involved in this modulation.

Analysis of Variance↗