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Biomedical subjects

L Sullivan

Publications and source records attributed to L Sullivan.

At least 37 records · Page 2Linked to original sources
PubMed1999

Small cell carcinoma of the bladder: long term outcome with integrated chemoradiation.

BACKGROUND: Small cell carcinoma of the bladder (SCCB) is an uncommon tumor with approximately 8% 5-year survival reported in the literature for patients with disease confined to the pelvis. It exhibits biologic behavior similar to that of small cell carcinoma of the lung (SCLC). The authors sought to determine whether etoposide and cisplatin chemotherapy integrated with local irradiation is associated with improved survival in SCCB, as has been shown in SCLC. METHODS: The authors performed a retrospective analysis of stage, treatment, disease free survival (DFS), and overall survival (OS) among 14 British Columbia Cancer Agency (BCCA) patients treated between 1985 and 1996 for SCCB. RESULTS: When multiagent chemotherapy was combined with local irradiation, the authors observed a 70% 2-year and 44% 5-year actuarial OS among 10 patients without contraindications to systemic chemotherapy. Actuarial DFS was 70% at 2 and 5 years. The mean survival was 47 months (95% confidence interval, 18.5-76.1 months) and the median survival was 41 months. Nine of these patients had disease confined to the pelvis, and one had metastases to retroperitoneal lymph nodes. Five patients were alive and disease free an average of 82 months following diagnosis. Two patients had died of other causes without evidence of disease at 34 and 48 months following diagnosis. The incidence of second primary transitional cell bladder neoplasms following successful treatment was 60% at 2 years (3 of 5 long term survivors). CONCLUSIONS: Integrated chemoradiation for patients with limited stage SCCB generates a realistic expectation of long term survival. Prospective trials to confirm these findings are warranted.

Adult↗
PubMed1999

Patient satisfaction with Department of Veterans Affairs health care: do women differ from men?

This study compared the patient satisfaction of female and male veterans using Department of Veterans Affairs health care and examined the relationship between sociodemographic characteristics and satisfaction in men and women. Using data from the Department of Veterans Affairs Women's Health Project (N = 719) and the Veterans Health Study (N = 600), we examined women's and men's unadjusted and adjusted mean scores on three dimensions of satisfaction: location of health care facility, access to health care, and prescription services. Although the unadjusted results indicated that women were less satisfied with both location and access, there were no differences in satisfaction with prescription services. After adjusting for age and then for both age and a recent physician visit, women remained less satisfied with location but were more satisfied with prescription services; there were no differences on access ratings. In an exploratory analysis, we examined the relationships between sociodemographic, military experience, and health characteristics and satisfaction within each sample. Older age was the only characteristic consistently positively associated with each dimension of satisfaction among both women and men. General health perceptions were positively associated with all three dimensions of women's satisfaction but with only the location dimension for men. Although other characteristics were associated with satisfaction within each sample, these differed for women and men. The results suggest that although there were not consistent differences in mean satisfaction ratings by gender, the characteristics associated with satisfaction differed for men and women.

Cross-Sectional Studies↗
PubMed1998

Butyrate analogue, isobutyramide, inhibits tumor growth and time to androgen-independent progression in the human prostate LNCaP tumor model.

Progression to androgen independence remains the main obstacle to improving survival and quality of life in patients with advanced prostate cancer. Induction of differentiation may serve as a rational basis for prevention of progression to androgen independence by modulating gene expression activated by castration or upregulated during androgen-independent progression. The objectives of this study were to characterize the in vitro effects of sodium butyrate on human prostate cancer cell growth, PSA gene expression, and differentiation in the LNCaP tumor model and to determine whether tumor progression in vivo is delayed by isobutyramide, an orally bioavailable butyrate analogue with a longer half-life. The effects of isobutyramide on LNCaP tumor growth and serum PSA levels in both intact and castrate male mice were compared to controls. At concentrations >1 mM, butyrate induced dose-dependent changes towards a more differentiated phenotype, G1 cell cycle arrest, and an 80% decrease in LNCaP cell growth rates. PSA gene expression was increased threefold by butyrate, indicative of differentiation-enhanced gene expression. The half-life of isobutyramide in athymic mice was determined by gas chromatography to be 4 h. During a 4 week period in intact-placebo mice, tumor volume and serum PSA increased 4.1- and 6.6-fold, respectively, compared to twofold and 2.7-fold increases in tumor volume and serum PSA in intact-treated mice. During a 7 week period in castrate-placebo mice, tumor volume and serum PSA levels increased 2.4-fold and fourfold, respectively, compared to a 50% reduction in tumor volume and a twofold increase in serum PSA above nadir levels in castrate mice treated with adjuvant isobutyramide. Isobutyramide treatment induced pronounced morphological changes in LNCaP tumor cells, with loss of defined nucleoli and dispersion of chromatin distribution. LNCaP tumor PSA mRNA levels actually increased threefold, indicative of differentiation-enhanced gene expression. This study demonstrates that butyrate causes LNCaP cell cycle arrest and increased PSA gene expression, both indicative of differentiation. The combination of castration and adjuvant isobutyramide was synergistic in delaying tumor progression. Decreased tumor cell proliferation and increased PSA gene expression induced by isobutyramide results in disconcordant changes in serum PSA and tumor volume and reduces the utility of serum PSA as a marker of response to therapy.

Administration, Oral↗
PubMed1998

Trillion virion delay: time from testing positive for HIV to presentation for primary care.

BACKGROUND: Human immunodeficiency virus (HIV)-infected individuals' initial presentation to medical care frequently occurs at a point of advanced immunosuppression. OBJECTIVES: To investigate the time between HIV testing and presentation to primary care. Also to examine factors associated with delayed presentation. METHODS: One hundred eighty-nine consecutive outpatients without prior primary care for HIV infection were assessed at 2 urban hospitals: Boston City Hospital, Boston, Mass, and Rhode Island Hospital, Providence. Sociodemographics, alcohol and drug use, social support, sexual beliefs and practices, and HIV testing issues were examined in bivariate and multivariate analyses for association with delay in presentation to primary care after positive test results for HIV. RESULTS: Of 189 patients, 74 (39%) delayed seeking primary care for more than 1 year, 61 (32%) delayed for more than 2 years, and 35 (18%) for more than 5 years after an initial positive HIV serologic evaluation. The median CD4+ cell count of subjects was 0.28 x 10(9)/L (range, 0.001-1.71 x 10(9)/L). In multiple linear regression analysis the following characteristics were found to be associated with delayed presentation to primary care after HIV testing: history of injection drug use (P<.001); not having a living mother (P=.01); not having a spouse or partner (P=.08); not being aware of HIV risk before testing (P<.001); and being notified of HIV status by mail or telephone (P=.002). An interaction effect between sex and screening for alcohol abuse was significant (P=.03) and suggested longer delays for men with positive screening test results (CAGE [an alcoholism screening questionnaire containing 4 structured questions], 2+) compared with men without positive screening test results or women. CONCLUSIONS: Patients with positive HIV test results often delay for more than a year before establishing primary medical care. Information readily available at the time of HIV testing concerning substance abuse, social support, and awareness of personal HIV risk status is useful in identifying patients who are at high risk of not linking with primary care. Patients who were notified of their HIV status by mail or telephone delayed considerably longer than those notified in person. Efforts to ensure primary care linkage at the time of notification of positive HIV serostatus are necessary to maximize benefits for both individual and public health and should be an explicit task of posttest counseling.

Alcohol Drinking↗
PubMed1998

Nutritional folate deficiency augments the in vivo mutagenic and lymphocytotoxic activities of alkylating agents.

To investigate the interaction of folate deficiency and alkylating agents in vivo, weanling Fischer 344 rats were maintained for 5 weeks on a folate replete, moderately folate deficient, or a severely folate deficient diet. Mutant frequencies at the HPRT locus in splenic lymphocytes were 1.2+/-0.6, 1.9+/-1.1, and 6.4+/-4.0 x 10(-6), respectively (P < 0.01). N-nitroso-N-ethylurea (ENU), 100 mg/kg body weight, was much more mutagenic with progressive folate deficiency (5.0+/-2.4 vs. 16.2+/-7.3 vs. 39.2+/-21.0 x 10(-6)), suggesting a synergistic interaction (P << 0.01). Neither moderate nor severe folate deficiency significantly enhanced the mutagenic effects of cyclophosphamide, 50 mg/kg body weight (18.0+/-7.9 vs. 6.0+/-2.8 vs. 28.5+/-28.2 x 10(-6)). The number of cloning cells/ spleen were reduced 68% in moderately folate deficient rats and by 87% in severely deficient animals (P < 0.05). The combination of folate deficiency and cyclophosphamide reduced the total number of cloning cells further, but ENU alone, or in combination with folate deficiency, did not. These findings indicate that folate deficiency increases the risk of somatic mutations and is lymphocytotoxic in rats. Folate deficiency enhances the mutagenic but not the lymphotoxic effects of ENU, while it increases the lymphotoxic but not the mutagenic activity of cyclophosphamide. Correction of folate deficiency may decrease the immunologic and genetic damage caused by some alkylating agents.

Alkylating Agents↗
PubMed1998

Aqueous solubilization of transmembrane peptide sequences with retention of membrane insertion and function.

We recently reported that the peptide C-K4-M2GlyR mimics the action of chloride channels when incorporated into the apical membrane of cultured renal epithelial monolayers. C-K4-M2GlyR is one of a series of peptides that were prepared by the addition of lysine residues to the N- or C-terminus of the M2 transmembrane sequence of the brain glycine receptor. This study addresses how such modifications affect physical properties such as aqueous solubility, aggregation, and secondary structure, as well as the ability of the modified peptides to form channels in epithelial monolayers. A graded improvement in solubility with a concomitant decrease in aggregation in aqueous media was observed for the M2GlyR transmembrane sequences. Increases in short-circuit current (I(SC)) of epithelial monolayers were observed after treatment with some but not all of the peptides. The bioactivity was higher for the more soluble, less aggregated M2GlyR peptides. As described in our previous communication, sensitivity of channel activity to diphenylamine-2-carboxylate, a chloride channel blocker, and bumetanide, an inhibitor of the Na/K/2Cl cotransporter, was used to assess changes in chloride selectivity for the different assembled channel-forming peptides. The unmodified M2GlyR sequence and the modified peptides with less positive charge are more sensitive to these agents than are the more highly charged forms. This study shows that relatively insoluble transmembrane sequences can be modified such that they are easier to purify and deliver in the absence of organic solvents with retention of membrane association, insertion, and assembly.

Amino Acid Sequence↗
PubMed1998

Wing-beat frequency mutants and courtship behavior in Drosophila melanogaster males.

Flightless mutations that affect wing-beat frequency (WBF) of Drosophila melanogaster were examined for their effect on male courtship. WBFs were measured using a fixed-wire tether that completely supports the fly in an attitude similar to hovering flight. The two spontaneous mutations, one of which reduces WBF to one-half normal and the other to zero, were placed on an isogenic background and were compared to an isogenic wildtype strain and to a genetically heterogeneous wildtype strain. Time to mating under noncompetitive conditions (single pair matings) was not significantly different among the four male types in one experiment. In a second experiment, although the time to mating varied significantly among the four male types, there was no association between the WBF that was characteristic of a male type and the length of time to mating. Time to mating was not significantly correlated with WBF, wing size, or body mass in either experiment. Genetically heterogeneous wild-type females were significantly more receptive (had shorter times to mating) than inbred wild-type females toward all four male types. During the time-to-mating tests, all four male types appeared to show typical courtship behaviors. Therefore, the male types were compared for possible differences in four components of the male courtship song: sine song frequency, interpulse interval, intrapulse frequency (= carrier frequency), and wing cycles per pulse. One or another of these components showed significant differences among the four male types (e.g., genetically heterogeneous, wild-type males showed a significantly higher sine song frequency and intrapulse frequency than males of the three isogenic types). However, the average values for all four male types were within reported wild-type ranges for each courtship song component. Although the two mutations drastically reduce WBF during tethered flight, they do not have any similar major effect on courtship. Apparently they affect muscles or neuronal control mechanisms that are not common elements shared by the wing movement of flight and male courtship song.

Animals↗
PubMed1998

Regional sympathetic function in high spinal cord injury during mental stress and autonomic dysreflexia.

Centrally mediated sympathetic stimulation of subjects who have suffered a spinal cord injury (SCI) does not activate the decentralized part of the body below the level of the lesion, whereas experimental data indicate an exaggerated response above the level of the lesion. SCI subjects may exhibit an autonomic dysreflexia reaction following afferent stimulation below the level of the lesion. In order to investigate the function of the sympathetic nervous system above and below the level of the lesion, regional noradrenaline spillover was measured by means of steady-state isotope dilution technique above (forearm) and below (leg) the level of the lesion at baseline, during mental stress and following bladder stimulation in nine SCI subjects (mean age 41 years; level of injury C7-T4; mean duration of injury 13.8 years). The results from the SCI subjects were also compared with those from 10 weight- and age-matched control subjects, both at rest and during mental stress. Body composition was determined by dual energy X-ray absorptiometry scanning and arm/leg blood flow by occlusion plethysmography. At baseline, total and regional noradrenaline spillover did not differ between the groups. Mental stress increased mean arterial pressure in both groups. Heart rate (76 versus 64 beats/min; P < 0.05) and arm noradrenaline spillover (2.73 versus 1.71 pmol/min/100 g; P < 0.05) increased more in spinal cord injury subjects than in control subjects, whereas total body (2826 versus 3783 pmol/min; P < 0.01) and leg noradrenaline spillover (0.23 versus 0.41 pmol/min/100 g; P < 0.05) increased only in the control group. During bladder stimulation, SCI subjects reacted with a marked increase in mean arterial pressure and leg noradrenaline spillover (from 0.06 to 0.91 pmol/min/100 g; P < 0.05) and their leg blood flow decreased. Regional and total noradrenaline clearance were similar in the two groups. In conclusion, peripheral afferent stimulation below the level of the lesion in spinal cord injury subjects gives rise to a marked noradrenaline spillover from the decentralized part of the sympathetic nervous system suggesting a remaining, but qualitatively altered, neuronal function. Centrally mediated stimulation induced an exaggerated response above the level of the lesion.

Absorptiometry, Photon↗
PubMed1997

Regulation of lipolysis by the sympathetic nervous system: a microdialysis study in normal and spinal cord-injured subjects.

To evaluate the regulation of lipolysis by the sympathetic nervous system, eight spinal cord-injured (SCI) subjects with a lesion above T5 resulting in a decentralization of the lower-body sympathetic nervous system and adrenal medulla (age, 36 +/- 2 years; weight, 82 +/- 5 kg; body fat mass, 26.8 +/- 3.0 kg; all mean +/- SE) and nine control subjects (age, 33 +/- 2; weight, 80 +/- 3; NS; body fat mass, 16.1 +/- 1.5 kg; P < .01) were investigated after fasting overnight. Each subject was studied with subcutaneous microdialysis and 133Xe-clearance adipose tissue blood flow (ATBF) in the umbilical and clavicular regions during postabsorptive rest and after sympathoexcitatory stimulation by means of mental stress and isometric handgrip exercise. SCI subjects had an increased body fat mass, hyperinsulinemia, and an elevated lipolytic rate at rest compared with control subjects. ATBF and lipolysis were activated to a normal extent following mental stress and isometric handgrip exercise in the umbilical region in control subjects. ATBF was increased in tissue above but not below the lesion level in SCI subjects following mental stress. Glycerol release was not different between groups in either tissue region despite significantly lower noradrenaline and adrenaline levels in SCI subjects. This finding argues against a significant adrenergic control of the lipolytic rate at rest. Furthermore, the small differences in stimulated glycerol release between groups, as well as the increased plasma glycerol levels in SCI subjects, cast doubt on the view that interruption of adrenergic activity below the lesion is the sole mechanism underlying the increased body fat mass in SCI subjects.

Adult↗
PubMed1997

Peripheral afferent stimulation of decentralized sympathetic neurons activates lipolysis in spinal cord-injured subjects.

Spinal cord-injured (SCI) subjects exhibit a normal lipolytic rate despite the failure of centrally mediated sympathoexcitatory stimuli to activate lipolysis. Peripheral afferent stimulation below the lesion level induces an exaggerated autonomic reaction in SCI with lesion levels above T5, ie, so-called autonomic dysreflexia. The metabolic effects of induced dysreflexia were investigated in five SCI subjects (age, 35 +/- 8 years; duration of paresis, 15 +/- 7.5 years [mean +/- SD]; lesion level, T3 to T4, n = 2, C7, n = 3) following bladder stimulation. Subcutaneous glycerol concentrations were measured by microdialysis above and below the lesion level. Diurnal plasma noradrenaline (NA) and adrenaline levels were continuously monitored in seven SCI subjects (lesion level T3 to T4, n = 2; C4 to C7, n = 5). Bladder stimulation resulted in an increased mean arterial pressure ([MAP] 81 +/- 8 to 114 +/- 11 mm Hg, P < .05), a decreased heart rate (70 +/- 3 to 54 +/- 4 beats/min, P < .05), and an increased plasma NA (0.70 +/- 0.49 v 3.27 +/- 1.56 nmol/L, P < .05). Interstitial glycerol was increased in the decentralized region (89 +/- 12 to 135 +/- 21 mumol/L, P < .05), whereas no reaction was found in the centrally innervated region. Plasma concentrations of glycerol and insulin increased. Diurnal monitoring showed periods of increased plasma NA sufficient to induce lipolysis (> 1.4 nmol/L) during 20% of the registration period. The data suggest that peripheral afferent stimulation below the lesion level increases NA release and activates lipolysis and that frequent episodes of activation are found in SCI subjects with tetraplegia or high paraplegia.

Adult↗
PubMed1997

Spinal cord injuries: a shortened measure of function and mood.

A brief quality-of-life (QL) questionnaire was derived empirically from a cross-sectional study of 98 SCI-patients (83% men, median age 33.5 years, and median time after injury 2.3 years). A comprehensive general battery of well-established questionnaires (Sickness Impact Profile (SIP), Mood Adjective Check List (MACL), and Hospital Anxiety and Depression (HAD) scale) was combined with a study-specific set of questions to constitute patients' QL. A stepwise analysis model was used to define key areas and questions to be included in a brief SCI-adapted questionnaire. The central areas that independently mattered for SCI-patients' perception of good QL included mental health (no depressive feelings), physical and psychosocial dysfunction (no, or few and minor, limitations in mobility, body care and movement and social interaction), and SCI-related problems (no or little perceived difficulty with loss of independence due to injury). A 22-item questionnaire is suggested for routine clinical follow-up to assess more accurately when optimal treatment and services have been delivered.

Activities of Daily Living↗
PubMed1997

The importance of osmolality in hydrophilic urethral catheters: a crossover study.

The longterm use of clean intermittent self catheterisation as an option for bladder management in the care of spinal cord injury patients has shown the possible risk of urethral trauma and chronic infections being developed over time. The basic properties of the catheters being used need to be evaluated. In this crossover study of 14 male spinal cord injury patients, two commercial hydrophilic catheters were compared, as to the maximum friction force during the removal of the catheters after bladder emptying. The friction force, measured by a dynamometer twice daily, showed significant lower values for LoFric (0.87/0.84 N) than for EsiCath/Conveen (1.38/1.27 N). Sticking to the urethral epithelium was reported three times (two patients) with the LoFric catheter, and 42 times (nine patients) with the EasiCath catheter. Osmolality of the outer layer of the catheters was measured using a freezing-point reduction technique. The greater than 10 times higher osmolality (approximately 900 mOsm/kg) of the Lofric catheter may explain the results.

Adult↗
PubMed1997

The effects of an HIV/AIDS educational programme on the anxiety level of nursing students.

Acquired immunodeficiency syndrome (AIDS) is a serious disease that has special concern for the health care provider. AIDS has continued to grow despite control efforts. As the disease infectivity period remains lengthy, and the heterosexual population is affected to a greater degree, the level of anxiety has also risen despite educational endeavours. Many fears and anxieties have been associated with AIDS patients by health care workers. The reduction of stress, perceived risk and discomfort following educational efforts have been supported in past research. Educational programmes will need to be given for current health care workers at all levels as well as nursing students. Future nurses must be prepared to meet this challenge. This study was conducted using a convenience sample of nursing students at a university in western United States. Its purpose was to assess any changes that occurred in state anxiety following an educational presentation. Spielberger's State-Trait Anxiety Inventory was used as the measurement instrument. Some anxiety levels were significantly reduced.

Adult↗
PubMed1997

Differentiated norepinephrine spillover in human skeletal muscle.

Most neurophysiological studies have shown similar sympathetic outflow to arm and leg. However, some direct microneurographic recordings indicate differentiated sympathetic outflow to limbs both at rest and during mental stress. Hence, differentiated levels of norepinephrine (NE) spillover could prevail. By steady-state infusion of [3H]NE and body composition determination by dual-energy X-ray absorptiometry-scan, we simultaneously assessed arm and leg NE spillover related to 100 g tissue and total limb weight. NE spillover was lower in leg than arm (0.26 vs. 1.51 pmol.min-1.100 g-1, P < 0.05), and the difference remained when expressed as a function of total limb weight (66 vs. 137 pmol/min, P < 0.05). Fractional extraction of [3H]NE was similar in arm and leg. Neuronal uptake blockade by desipramine was more effective in leg than arm; fractional extraction in leg decreased by 32% (P < 0.05) but was unaltered in arm. Thus a lower NE spillover was observed from leg than arm, possibly reflecting a lower sympathetic outflow and a more neuronally dependent reuptake.

Absorptiometry, Photon↗
PubMed1997

Bovine tuberculosis in free-ranging white-tailed deer from Michigan.

A 4.5 yr-old male white-tailed deer (Odocoileus virginianus) killed by a hunter during the 1994 firearm hunting season in northeastern Michigan (USA) had lesions suggestive of tuberculosis and was positive on culture for Mycobacterium bovis the causative agent for bovine tuberculosis. Subsequently, a survey of 354 hunter-harvested white-tailed deer for tuberculosis was conducted in this area from 15 November 1995 through 5 January 1996. Heads and/or lungs from deer were examined grossly and microscopically for lesions suggestive of bovine tuberculosis. Gross lesions suggestive of tuberculosis were seen in 15 deer. Tissues from 16 deer had acid-fast bacilli on histological examination and in 12 cases mycobacterial isolates from lymph nodes and/or lungs were identified as M. bovis. In addition, lymph nodes from 12 deer (11 females and 1 male) without gross or microscopic lesions were pooled into 1 sample from which M. bovis was cultured. Although more male (9) than female (3) deer had bovine tuberculosis infections, this difference was not statistically significant. Mycobacterium bovis culture positive deer ranged in age from 1.5 to 5.5 yr with a mean of 2.7 yr (median 2.5 yr) for males and 3.2 yr (median 3.5 yr) for females. This appears to be the first epidemic occurrence of M. bovis in free-ranging cervids in North America. A combination of environmental (high deer density and poor quality habit) and management-related factors (extensive supplemental feeding) may be responsible for this epizootic.

Animals↗
PubMed1996

Genetic mapping of RP1 on 8q11-q21 in an Australian family with autosomal dominant retinitis pigmentosa reduces the critical region to 4 cM between D8S601 and D8S285.

The locus (RP1) for one form of autosomal dominant retinitis pigmentosa (adRP) was mapped on chromosome 8q11-q22 between D8S589 and D8S285, which are about 8 cM apart, by linkage analysis in an extended family ascertained in the USA. We have studied a multigeneration Australian family with adRP and found close linkage without recombination between the disease locus and D8S591, D8S566, and D8S166 (Zmax = 1.137-4.650 at theta = 0.00), all mapped in the region known to harbor RP1. Assuming that the mutation of the same gene is responsible for the disease in both families, the analysis of multiply informative meioses in the American and Australian families places the adRP locus between D8S601 and D8S285, which reduces the critical region to about 4 cM, corresponding to approximately 4 Mb, which is completely covered by a yeast artificial chromosome contig assembled recently.

Adult↗
PubMed1996

Electromyographical evidence for exercise-induced diaphragm fatigue in patients with chronic cervical cord injury or prior poliomyelitis infection.

UNLABELLED: The purpose of this study was to determine, in exercising patients, how much diaphragm force increases before electromyographical evidence of diaphragm fatigue occurs. The study was performed in ten male patients with complete cervical cord injury (CCI) at the C5 to C8 levels, and five male patients with prior poliomyelitis infection (PPI) requiring chronic treatment with intermittent positive pressure ventilation (IPPV) at night. We studied the time course of the diaphragmatic tension-time index (TTdi), the centre frequency (CFdi) of the diaphragm electromyogram (EMGdi) power spectrum, and the ventilatory parameters, during steady-state submaximal arm/leg exercise. During exercise, early signs of diaphragm fatigue were present in seven out of 10 CCI patients and in four out of five PPI patients, as indicated by a reduction in CFdi. The increase in TTdi achieved before reductions in CFdi occurred was twofold in both the CCI and PPI patients. All patients except for the PPI patients, who demonstrated a reduction in CFdi, showed an increase in minute ventilation (VE), achieved by increasing both their tidal volume (Vt) and the breathing frequency (fb). The PPI patients demonstrating reductions in CFdi during exercise also increased their VE however, this was achieved by increasing fb while Vt remained constant. Following the reductions in CFdi, the CCI patients further increased their TTdi throughout the exercise test, while the PPI patients reduced their TTdi values. IN CONCLUSION: (1) During exercise, electromyographical evidence for diaphragmatic fatigue frequently occurred in the CCI and PPI patients studied; (2) Compared to the eightfold increase in TTdi seen in healthy subjects before reductions in CFdi occur, the TTdi values increased only two-fold before electromyographical evidence of diaphragm fatigue was present in these patients; (3) There is a clear discrepancy between the CCI and PPI patients who demonstrate electromyographical evidence of diaphragm fatigue, in terms of their ventilatory and TTdi responses.

Adult↗