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Biomedical subjects

M A Cohen

Publications and source records attributed to M A Cohen.

At least 19 recordsLinked to original sources
PubMed2006

Noise exposure and hearing loss prevention programmes after 20 years of regulations in the United States.

OBJECTIVES: To evaluate noise exposures and hearing loss prevention efforts in industries with relatively high rates of workers' compensation claims for hearing loss. METHODS: Washington State workers' compensation records were used to identify up to 10 companies in each of eight industries. Each company (n = 76) was evaluated by a management interview, employee personal noise dosimetry (n = 983), and employee interviews (n = 1557). RESULTS: Full-shift average exposures were > or =85 dBA for 50% of monitored employees, using Occupational Safety and Health Administration (OSHA) parameters with a 5 dB exchange rate (L(ave)), but 74% were > or =85 dBA using a 3 dB exchange rate (L(eq)). Only 14% had L(ave) > or =90 dBA, but 42% had L(eq) > or =90 dBA. Most companies conducted noise measurements, but most kept no records, and consideration of noise controls was low in all industries. Hearing loss prevention programmes were commonly incomplete. Management interview scores (higher score = more complete programme) showed significant associations with percentage of employees having L(ave) > or =85 dBA and presence of a union (multiple linear regression; R2 = 0.24). Overall, 62% of interviewed employees reported always using hearing protection when exposed. Protector use showed significant associations with percentage of employees specifically required to use protection, management score, and average employee time spent > or =95 dBA (R2 = 0.65). CONCLUSIONS: The findings raise serious concerns about the adequacy of prevention, regulation, and enforcement strategies in the United States. The percentage of workers with excessive exposure was 1.5-3 times higher using a 3 dB exchange rate instead of the OSHA specified 5 dB exchange rate. Most companies gave limited or no attention to noise controls and relied primarily on hearing protection to prevent hearing loss; yet 38% of employees did not use protectors routinely. Protector use was highest when hearing loss prevention programmes were most complete, indicating that under-use of protection was, in some substantial part, attributable to incomplete or inadequate company efforts.

Adult↗
PubMed2005

Self-reported musculoskeletal symptoms and observed risk factors in bareroot tree nurseries.

A cross-sectional study of jobs at four bareroot reforestation tree nurseries in Washington and Oregon investigated the prevalence of musculoskeletal symptoms and potential work-related musculoskeletal disorders (WMSDs), and analyzed their association with physical and psychosocial risk factors of the jobs. Questionnaires were used to assess symptoms and psychosocial factors. Direct observational work sampling was utilized to estimate physical risk factors. The response rate for the questionnaires was 41% (203 subjects), of which 72% reported recurring symptoms in the past year. The most common body region was the wrist/hand (42%). Pain was the most commonly reported symptom. Forty-one percent of the subjects had at least one potential WMSD, the hand region having the greatest number of cases (n = 51). The average age of those with and without potential WMSDs did not significantly differ; however, tenure at the nursery (p < 0.03) did. Being female (OR = 7.37; 95% CI = 2.75, 19.7,) high job satisfaction (OR = 0.32; 95% CI = 0.15, 0.72), and having a second job (OR = 3.76; 95% CI = 1.12, 12.57) were significantly associated with potential WMSDs. No significant difference in WMSD prevalence was found between the field and packing shed areas of the nurseries (p = 0.88). Pinch gripping was observed 24% of the time in the shed and 8% of the time in the field. Torso flexion was observed more often in the field than the shed (38% vs. 18% of the time). This study found that both physical and psychosocial factors associated with WMSDs are present in bareroot trees nurseries.

Adult↗
PubMed2003

Pancreatic polypeptide reduces appetite and food intake in humans.

Pancreatic polypeptide (PP) is a gut hormone released from the pancreas in response to ingestion of food. Plasma PP has been shown to be reduced in conditions associated with increased food intake and elevated in anorexia nervosa. In addition peripheral administration of PP has been shown to decrease food intake in rodents. These findings suggest that PP may act as a circulating factor that regulates food intake. Therefore we investigated the effect of intravenous infusion of PP (10 pmol/kg/min) on appetite and food intake in a randomised double-blind placebo-controlled crossover study in ten healthy volunteers. Infusion of PP reduced appetite and decreased the energy intake at a buffet lunch two hours post-infusion by 21.8 +/- 5.7% (P < 0.01). More importantly the inhibition of food intake was sustained, such that energy intake, as assessed by food diaries, was significantly reduced both the evening of the study and the following morning. Overall PP infusion reduced cumulative 24-hour energy intake by 25.3 +/- 5.8%. In conclusion our data demonstrates that PP causes a sustained decrease in both appetite and food intake.

Adolescent↗
PubMed2002

Chronic intraparaventricular nuclear administration of orexin A in male rats does not alter thyroid axis or uncoupling protein-1 in brown adipose tissue.

Orexin A, synthesised in the posterolateral hypothalamus, has widespread distribution including the paraventricular nucleus (PVN), which is rich in thyrotropin-releasing hormone (TRH) neurones. Nerve fibres in the PVN synapse on neurones that send polysynaptic projections to brown adipose tissue (BAT), which is important in thermogenesis. A number of observations suggests orexin A may be involved in regulation of metabolism and thermogenesis. We investigated the effect of orexin A injected intracerebroventricularly (ICV) on thyroid-stimulating hormone (TSH) and thyroid hormones in male rats. We then examined the effect of chronic iPVN injections of orexin A on plasma TSH and uncoupling protein-1 (UCP-1) protein in BAT. Orexin A (3 nmol) administered ICV significantly suppressed plasma TSH at 10 and 90 min. Orexin A (0.3 nmol) administered into the PVN twice daily for 3 days significantly increased day-time 2-h food intake, but did not significantly alter nocturnal food intake. Though chronic iPVN orexin A altered diurnal food intake, there was no effect on 24-h food intake or body weight. Furthermore, orexin A administered chronically into the PVN did not alter UCP-1 level in BAT, or plasma hormones relative to saline injected animals. Chronic iPVN orexin A does not appear to influence thermogenesis through activation of UCP-1 or the thyroid axis.

Adipose Tissue, Brown↗
PubMed2002

The effect of fibrolytic enzymes sprayed onto forages and fed in a total mixed ratio to lactating dairy cows.

We investigated the effect of spraying different combinations of fibrolytic enzymes onto forages on their nutritive value for lactating cows. Holstein cows were fed a TMR consisting of 30% corn silage, 15% alfalfa hay, and 55% concentrate (dry matter basis). During a 12-wk treatment period, the forages were treated with no enzymes (control), cellulase D and sultanas B, or cellulase D and xylanase C. Enzymes were diluted in water and sprayed onto the forages while mixing. Both combinations of enzymes supplied similar amounts of fibrolytic activity based on classical enzyme assays conducted at 50 degrees C. Cows fed forages treated with cellulase D and xylanase B tended to produce more 3.5% FCM (+2.5 kg/d) than did cows fed the untreated forages. Dry matter intake, milk production, milk fat, and milk protein were unaffected by treatment. In vitro production of gas from forages treated with enzymes was greater than from untreated forage, but 96-h volatile fatty acid production was not different among treatments. With an alternative enzyme assay based on the depolymerization of dyed substrate at 40 degrees C, activity of xylanase C was greatest at a pH of 6.5 but was substantially reduced as the pH of the assay was decreased. In contrast, xylanase B showed highest activity at pH 5 and enzyme activity was twice that of xylanase B at pH 5.5 and 6. Overall, the results of this study provide more evidence that fibrolytic enzymes can be used to improve milk production in lactating cows.

Animal Feed↗
PubMed2001

A model for the genesis of arterial pressure Mayer waves from heart rate and sympathetic activity.

Both theoretic models and cross-spectral analyses suggest that an oscillating sympathetic nervous outflow generates the low-frequency arterial pressure fluctuations termed Mayer waves. Fluctuations in heart rate also have been suggested to relate closely to Mayer waves, but empiric models have not assessed the joint causative influences of heart rate and sympathetic activity. Therefore, we constructed a model based simply upon the hemodynamic equation derived from Ohm's Law. With this model, we determined time relations and relative contributions of heart rate and sympathetic activity to the genesis of arterial pressure Mayer waves. We assessed data from eight healthy young volunteers in the basal state and in a high sympathetic state known to produce concurrent increases in sympathetic nervous outflow and Mayer wave amplitude. We fit the Mayer waves (0.05-0.20 Hz) in mean arterial pressure by the weighted sum of leading oscillations in heart rate and sympathetic nerve activity. This model of our data showed heart rate oscillations leading by 2-3.75 s were responsible for almost half of the variance in arterial pressure (basal R2 = 0.435 +/- 0.140, high sympathetic R2= 0.438 +/- 0.180). Surprisingly, sympathetic activity (lead 0-5 s) contributed only modestly to the explained variance in Mayer waves during either sympathetic state (basal: delta R2 = 0.046 +/- 0.026; heightened: delta R2 = 0.085 +/- 0.036). Thus, it appears that heart rate oscillations contribute to Mayer waves in a simple linear fashion, whereas sympathetic fluctuations contribute little to Mayer waves in this way. Although these results do not exclude an important vascular sympathetic role, they do suggest that additional factors, such as sympathetic transduction into vascular resistance, modulate its influence.

Adult↗
PubMed2001

Recombinant human platelet-derived growth factor gel speeds healing of acute full-thickness punch biopsy wounds.

BACKGROUND: Recombinant human platelet derived growth factor-BB gel (PDGF gel) has been shown to be effective in the treatment of diabetic neuropathic ulcers. It is also being used off-label to speed wound healing of flaps, grafts, and wounds from Mohs micrographic surgery. OBJECTIVE: The purpose of the study was to compare the rate of healing in wounds treated with PDGF gel and with wounds treated with conventional therapy (antibiotic ointment). METHODS: A double-blind controlled study of 7 healthy volunteers was performed. With a 4-mm skin punch biopsy instrument, two full-thickness wounds were made on each arm of each volunteer. Fourteen wounds treated with PDGF gel were compared with 14 wounds treated with antibiotic ointment. Healing was evaluated by visual determination of the global percentage healed and wound depth. RESULTS: Wounds treated with PDGF gel showed a significantly faster rate of healing on each of the initial 6 follow-up visits. The greatest difference was on day 10 when PDGF-treated wounds were 71% healed compared with 28% for antibiotic-treated wounds (P =.0005). At days 22 and 24, 92.9% and 100% of the PDGF gel-treated wounds were healed, compared with 50% and 57%, respectively (P =.0313 and P =.0313), in the antibiotic ointment group. By day 29, both PDGF gel and antibiotic-treated wounds were healed. PDGF also decreased wound depth compared with wounds treated with antibiotic ointment at days 8 and 10 with P values <.0313 and <.0020, respectively. CONCLUSION: We conclude that PDGF gel speeds healing of acute full-thickness wounds compared with antibiotic ointment.

Adult↗
PubMed2001

Patterns of informal and formal caregiving among elders with private long-term care insurance.

PURPOSE: The purpose of this report is to provide basic descriptive information on community-dwelling, disabled, private long-term care (LTC) insurance policyholders who have accessed policy benefits. We focus on how benefits are used, whether claimants feel they are getting appropriate value from their policies, and what the patterns are of formal and informal service use. DESIGN AND METHODS: Data were obtained from a nationally representative sample of 693 LTC insurance claimants who were receiving benefits while living in the community and 424 of their informal caregivers. Eight of the largest LTC insurance companies representing about 80% of the market participated in the study. RESULTS: LTC insurance benefits are well targeted; they serve those truly dependent on ongoing care. The vast majority of claimants are satisfied with their policies, understand their coverage, and find it easy to file claims. Because of their LTC benefits, substantial numbers of disabled elderly individuals report that they are able to remain at home instead of being forced to seek institutional care. The availability of LTC benefits reduces stress among informal caregivers. For most claimants, formal care did not replace informal caregiving. IMPLICATIONS: As the LTC insurance market continues to grow and mature, there will be changes in the profile of claimants, the service delivery system, and the design of policies. Expansions in the private market will be associated with a greater number of disabled elderly remaining in their homes with a maintenance of and enhanced resiliency of informal support networks.

Aged↗
PubMed2001

Laryngopharyngeal sensory deficits as a predictor of aspiration.

OBJECTIVE: This study evaluates whether patients with severe sensory deficits in the hypopharynx are at increased risk for aspiration and determines the relationship between pharyngeal muscular weakness and hypopharyngeal sensory deficits. STUDY DESIGN AND SETTING: Forty patients with dysphagia who underwent flexible endoscopic evaluation of swallowing with sensory testing were prospectively divided into 2 groups. One group included patients with severe sensory deficits determined by an absent laryngeal adductor reflex and the other with normal sensitivity. Subjects were given liquid and puree consistencies and were evaluated for aspiration as well as pharyngeal muscle contraction. RESULTS: The differences in incidence of aspiration and pharyngeal muscular weakness between the 2 groups were significant (P < 0.001 Fisher's exact test). CONCLUSION: There is a strong association between motor function deficits and hypopharyngeal sensory deficits. SIGNIFICANCE: The association of sensory loss and motor deficits together with the use of flexible endoscopic evaluation of swallowing with sensory testing can predict those patients who are at highest risk for aspiration.

Adult↗
PubMed2001

Ghrelin enhances appetite and increases food intake in humans.

Ghrelin is a recently identified endogenous ligand for the growth hormone secretagogue receptor. It is synthesized predominantly in the stomach and found in the circulation of healthy humans. Ghrelin has been shown to promote increased food intake, weight gain and adiposity in rodents. The effect of ghrelin on appetite and food intake in man has not been determined. We investigated the effects of intravenous ghrelin (5.0 pmol/kg/min) or saline infusion on appetite and food intake in a randomised double-blind cross-over study in nine healthy volunteers. There was a clear-cut increase in energy consumed by every individual from a free-choice buffet (mean increase 28 +/- 3.9%, p<0.001) during ghrelin compared with saline infusion. Visual analogue scores for appetite were greater during ghrelin compared to saline infusion. Ghrelin had no effect on gastric emptying as assessed by the paracetamol absorption test. Ghrelin is the first circulating hormone demonstrated to stimulate food intake in man. Endogenous ghrelin is a potentially important new regulator of the complex systems controlling food intake and body weight.

Adult↗
PubMed2001

Ghrelin causes hyperphagia and obesity in rats.

Ghrelin, a circulating growth hormone-releasing peptide derived from the stomach, stimulates food intake. The lowest systemically effective orexigenic dose of ghrelin was investigated and the resulting plasma ghrelin concentration was compared with that during fasting. The lowest dose of ghrelin that produced a significant stimulation of feeding after intraperitoneal injection was 1 nmol. The plasma ghrelin concentration after intraperitoneal injection of 1 nmol of ghrelin (2.83 +/- 0.13 pmol/ml at 60 min postinjection) was not significantly different from that occurring after a 24-h fast (2.79 +/- 0.32 pmol/ml). After microinjection into defined hypothalamic sites, ghrelin (30 pmol) stimulated food intake most markedly in the arcuate nucleus (Arc) (0-1 h food intake, 427 +/- 43% of control; P < 0.001 vs. control, P < 0.01 vs. all other nuclei), which is potentially accessible to the circulation. After chronic systemic or intracerebroventricular (ICV) administration of ghrelin for 7 days, cumulative food intake was increased (intraperitoneal ghrelin 13.6 +/- 3.4 g greater than saline-treated, P < 0.01; ICV ghrelin 19.6 +/- 5.5 g greater than saline-treated, P < 0.05). This was associated with excess weight gain (intraperitoneal ghrelin 21.7 +/- 1.4 g vs. saline 10.6 +/- 1.9 g, P < 0.001; ICV ghrelin 15.3 +/- 4.3 g vs. saline 2.2 +/- 3.8 g, P < 0.05) and adiposity. These data provide evidence that ghrelin is important in long-term control of food intake and body weight and that circulating ghrelin at fasting concentrations may stimulate food intake.

Animals↗
PubMed2001

Private LTC insurance. The home care claimant experience.

An understanding of claimants and their behavior should help consumers make more informed choices about financing their potential LTC needs, help the private insurance industry better meet those needs, and inform public policies designed to support and regulate the market. To this end, LifePlans, Inc. and the Center for Health and Long-Term Care Research conducted in-person interviews with more than 1,000 private long-term care insurance claimants residing both in the community and in institutions.

Aged↗
PubMed2001

Controlled ovarian hyperstimulation. Relationship of early serum E2 levels to the ultimate response of oocyte donors.

OBJECTIVE: To assess the predictive value of measuring serum day 5 E2 and in vitro fertilization (IVF) cycle outcome of oocyte donors undergoing controlled ovarian hyperstimulation (COH). STUDY DESIGN: Retrospective data analysis. RESULTS: Day 5 E2 significantly correlated with the peak serum E2 and number of retrieved mature oocytes. The pregnancy rates associated with stimulated day 5 E2 > 70 pg/mL were significantly greater than in cycles with levels < 70 pg/mL (58%, 71/123, versus 25%, 15/60; P < .05). CONCLUSION: The cycle performance of an oocyte donor can be predicted by measuring cycle day 5 serum E2 during COH. Poor-prognosis cycles can be identified and discontinued, saving patients and the program unnecessary exspense.

Adult↗
PubMed2000

FKF1, a clock-controlled gene that regulates the transition to flowering in Arabidopsis.

Plant reproduction requires precise control of flowering in response to environmental cues. We isolated a late-flowering Arabidopsis mutant, fkf1, that is rescued by vemalization or gibberellin treatment. We positionally cloned FKF1, which encodes a novel protein with a PAS domain similar to the flavin-binding region of certain photoreceptors, an F box characteristic of proteins that direct ubiquitin-mediated degradation, and six kelch repeats predicted to fold into a beta propeller. FKF1 mRNA levels oscillate with a circadian rhythm, and deletion of FKF1 alters the waveform of rhythmic expression of two clock-controlled genes, implicating FKF1 in modulating the Arabidopsis circadian clock.

Amino Acid Sequence↗
PubMed2000

Prognostic implications of mandibular invasion in oral cancer.

BACKGROUND: Mandibular invasion alters the clinical staging and management of oral epidermoid carcinoma on the assumption that underresection of mandibular bone invaded by tumor can result in disease progression and poor outcome. METHODS: Cox's proportional hazard model was used to assess the effect of mandibular invasion on recurrence-free survival in 107 patients with squamous cell carcinoma of the oral cavity after controlling for the potential confounding effect of positive margins, tumor size, nodal status, and type of resection. RESULTS: Mandibular invasion was characterized as none (n = 59), focal (n = 25), or deep (n = 23). Relapse-free survival at 60 months by the Kaplan Meier product limit method for the none, focal, and deep invasion groups was 61%, 73%, and 46% respectively (p =.28). Variables influencing disease recurrence were positive margins, size >2 cm, N2 and N3 nodal disease, and marginal vs segmental mandibular resection. Mandibular invasion was not a significant risk factor for disease recurrence with an adjusted hazard ratio for deep invasion vs focal or no invasion of 1.0 (95% CI = 0.5, 2.2; p = 1.00). CONCLUSIONS: Detection of bone invasion, particularly in small tumors, may not be as critical to surgical planning as previously expected. The necessity for and extent of bone resection should be determined by the objective of achieving an adequate surgical margin and not the presence of bone invasion per se.

Adult↗