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1.
BMJ Mil Health ; 168(3): 206-211, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-32423898

RESUMO

INTRODUCTION: Cadets participating in Reserve Officers' Training Corp (ROTC) at US universities undergo both Army Physical Fitness Test (APFT) and Occupational Physical Assessment Test (OPAT) evaluations prior to commissioning. The current study examined the relationship between ROTC physical training (PT) attendance and performance in the APFT and OPAT, and characterised physical activity of cadets outside of PT. METHODS: Twenty-six cadets' (21 males; age=20.81±2.48 years; height=171.16±8.62 cm; body mass=75.49±13.17 kg; body mass index=25.68±3.37 kg/m2) PT attendance, and diagnostic (week 1) and record (week 13) OPAT and APFT scores were documented. Paired samples t-tests evaluated differences in APFT and OPAT scores between the diagnostic and record tests. Pearson correlations were utilised to determine if a relationship existed between PT attendance and test performance. Participating cadets also completed monthly self-reported physical activity questionnaire (September, October, November); findings were reported using descriptive statistics. RESULTS: Cadets attended 87% of PT sessions between OPAT administrations and 85% between APFT administrations. Cadets significantly improved the following test components: standing long jump (p=0.034), seated power throw (p=0.029), shuttle run (p=0.005), sit-ups (p=0.003) and 2-mile run (p=0.045). A significant, positive correlation was found between PT attendance and APFT sit-ups improvements (r=0.473, p=0.015). Cadets' frequently reported additional physical activity days per week (range: 2.8-3.1 aerobic, 3.2-3.8 strength/power, 2.9-3.2 core strength/endurance). CONCLUSIONS: Regular participation in a single semester of ROTC PT was found to significantly increase cadets' scores in some, but not all, components of the APFT and OPAT. Self-reported physical activity results indicate that cadets regularly train outside of organised PT.


Assuntos
Teste de Esforço , Militares , Adolescente , Adulto , Índice de Massa Corporal , Teste de Esforço/métodos , Humanos , Masculino , Aptidão Física , Estados Unidos , Universidades , Adulto Jovem
2.
Clin Genet ; 98(4): 331-340, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32666529

RESUMO

Childhood dilated cardiomyopathy (DCM) is a leading cause of heart failure requiring cardiac transplantation and approximately 5% of cases result in sudden death. Knowledge of the underlying genetic cause can aid prognostication and clinical management and enables accurate recurrence risk counselling for the family. Here we used genomic sequencing to identify the causative genetic variant(s) in families with children affected by severe DCM. In an international collaborative effort facilitated by GeneMatcher, biallelic variants in PPP1R13L were identified in seven children with severe DCM from five unrelated families following exome or genome sequencing and inheritance-based variant filtering. PPP1R13L encodes inhibitor of apoptosis-stimulating protein of p53 protein (iASPP). In addition to roles in apoptosis, iASPP acts as a regulator of desmosomes and has been implicated in inflammatory pathways. DCM presented early (mean: 2 years 10 months; range: 3 months-9 years) and was progressive, resulting in death (n = 3) or transplant (n = 3), with one child currently awaiting transplant. Genomic sequencing technologies are valuable for the identification of novel and emerging candidate genes. Biallelic variants in PPP1R13L were previously reported in a single consanguineous family with paediatric DCM. The identification here of a further five families now provides sufficient evidence to support a robust gene-disease association between PPP1R13L and severe paediatric DCM. The PPP1R13L gene should be included in panel-based genetic testing for paediatric DCM.


Assuntos
Cardiomiopatia Dilatada/genética , Predisposição Genética para Doença , Peptídeos e Proteínas de Sinalização Intracelular/genética , Pediatria , Proteínas Repressoras/genética , Alelos , Cardiomiopatia Dilatada/patologia , Cardiomiopatia Dilatada/terapia , Criança , Pré-Escolar , Exoma/genética , Feminino , Testes Genéticos , Humanos , Lactente , Masculino , Linhagem
3.
Clin Genet ; 92(1): 3-9, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-27625340

RESUMO

Baraitser-Winter cerebrofrontofacial syndrome (BWCFF) (BRWS; MIM #243310, 614583) is a rare developmental disorder affecting multiple organ systems. It is characterised by intellectual disability (mild to severe) and distinctive facial appearance (metopic ridging/trigonocephaly, bilateral ptosis, hypertelorism). The additional presence of cortical malformations (pachygyria/lissencephaly) and ocular colobomata are also suggestive of this syndrome. Other features include moderate short stature, contractures, congenital cardiac disease and genitourinary malformations. BWCFF is caused by missense mutations in the cytoplasmic beta- and gamma-actin genes ACTB and ACTG1. We provide an overview of the clinical characteristics (including some novel findings in four recently diagnosed patients), diagnosis, management, mutation spectrum and genetic counselling.


Assuntos
Anormalidades Múltiplas/genética , Actinas/genética , Anormalidades Craniofaciais/genética , Deficiências do Desenvolvimento/genética , Transtornos do Crescimento/genética , Hidrocefalia/genética , Deficiência Intelectual Ligada ao Cromossomo X/genética , Obesidade/genética , Anormalidades Múltiplas/diagnóstico , Anormalidades Múltiplas/fisiopatologia , Anormalidades Craniofaciais/diagnóstico , Anormalidades Craniofaciais/fisiopatologia , Deficiências do Desenvolvimento/diagnóstico , Deficiências do Desenvolvimento/fisiopatologia , Fácies , Aconselhamento Genético , Transtornos do Crescimento/diagnóstico , Transtornos do Crescimento/fisiopatologia , Humanos , Hidrocefalia/diagnóstico , Hidrocefalia/fisiopatologia , Deficiência Intelectual Ligada ao Cromossomo X/diagnóstico , Deficiência Intelectual Ligada ao Cromossomo X/fisiopatologia , Mutação de Sentido Incorreto/genética , Obesidade/diagnóstico , Obesidade/fisiopatologia
4.
J Med Genet ; 47(11): 760-8, 2010 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-20685669

RESUMO

BACKGROUND: Silver-Russell syndrome (SRS) is characterised by intrauterine growth restriction, poor postnatal growth, relative macrocephaly, triangular face and asymmetry. Maternal uniparental disomy (mUPD) of chromosome 7 and hypomethylation of the imprinting control region (ICR) 1 on chromosome 11p15 are found in 5-10% and up to 60% of patients with SRS, respectively. As many features are non-specific, diagnosis of SRS remains difficult. Studies of patients in whom the molecular diagnosis is confirmed therefore provide valuable clinical information on the condition. METHODS: A detailed, prospective study of 64 patients with mUPD7 (n=20) or ICR1 hypomethylation (n=44) was undertaken. RESULTS AND CONCLUSIONS: The considerable overlap in clinical phenotype makes it difficult to distinguish these two molecular subgroups reliably. ICR1 hypomethylation was more likely to be scored as 'classical' SRS. Asymmetry, fifth finger clinodactyly and congenital anomalies were more commonly seen with ICR1 hypomethylation, whereas learning difficulties and referral for speech therapy were more likely with mUPD7. Myoclonus-dystonia has been reported previously in one mUPD7 patient. The authors report mild movement disorders in three further cases. No correlation was found between clinical severity and level of ICR1 hypomethylation. Use of assisted reproductive technology in association with ICR1 hypomethylation seems increased compared with the general population. ICR1 hypomethylation was also observed in affected siblings, although recurrence risk remains low in the majority of cases. Overall, a wide range of severity was observed, particularly with ICR1 hypomethylation. A low threshold for investigation of patients with features suggestive, but not typical, of SRS is therefore recommended.


Assuntos
Epigênese Genética , Estudos de Associação Genética/métodos , Síndrome de Silver-Russell/genética , Adolescente , Adulto , Criança , Pré-Escolar , Cromossomos Humanos Par 11/genética , Cromossomos Humanos Par 7/genética , Metilação de DNA , Feminino , Impressão Genômica , Humanos , Lactente , Masculino , Canais de Potássio de Abertura Dependente da Tensão da Membrana/genética , Estudos Prospectivos , RNA Longo não Codificante , RNA não Traduzido/genética , Síndrome de Silver-Russell/patologia , Dissomia Uniparental , Adulto Jovem
5.
Am J Med Genet A ; 149A(2): 161-70, 2009 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-19161152

RESUMO

Mutations in the gene encoding fibrillin 1 (FBN1) cause Marfan syndrome (MFS), and related connective tissue disorders. The disease spectrum is wide and while many genotype-phenotype correlations have been reported, few have been consistent. In this study FBN1 was analyzed in 113 patients with MFS or Marfan-like features. Fifty-three mutations were identified in 52 individuals, 41 of which were novel. The mutations comprised 26 missense, 11 splice site, 7 frameshift, 6 nonsense, 1 in-frame deletion, and 2 whole exon deletions. In common with previous studies, genotype-phenotype analysis showed that a FBN1 mutation was more likely to be identified in patients fulfilling Ghent criteria (P = 0.005) and in those who had ectopia lentis (EL) (P < 0.0001). Other previously reported genotype-phenotype correlations were also considered and a new inverse association between a mutation in exons 59-65, and EL emerged (P = 0.002).


Assuntos
Síndrome de Marfan/genética , Proteínas dos Microfilamentos/genética , Mutação , Adolescente , Adulto , Criança , Pré-Escolar , Doenças do Tecido Conjuntivo , Análise Mutacional de DNA , Ectopia do Cristalino , Feminino , Fibrilina-1 , Fibrilinas , Genótipo , Humanos , Masculino , Pessoa de Meia-Idade , Fenótipo , Adulto Jovem
8.
Transfusion ; 43(9): 1200-9, 2003 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-12919421

RESUMO

BACKGROUND: Incorrect blood component transfusion is the most frequent serious incident associated with transfusion. Errors responsible for these incidents frequently involve patient misidentification. STUDY DESIGN AND METHODS: This study evaluated a barcode patient identification system involving hand-held computers for blood sample collection for compatibility testing and the administration of blood. Audit of practice was carried out before and after its introduction. RESULTS: The baseline audit revealed poor practice, particularly in patient identification. Significant improvements were found in the procedure for the administration of blood following the introduction of barcode patient identification, including an improvement from 11.8 to 100 percent in the correct verbal identification of patients (p

Assuntos
Transfusão de Sangue/normas , Computadores de Mão , Sistemas de Identificação de Pacientes/métodos , Estudos de Avaliação como Assunto , Humanos , Pacientes Internados , Capacitação em Serviço , Auditoria Médica
9.
J Neurol Neurosurg Psychiatry ; 74(4): 533-5, 2003 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-12640085

RESUMO

Applanation tonometry is a non-invasive method of assessing the arterial blood pressure profiles in both the peripheral and systemic circulation. In this study the authors examined whether there were differences in these profiles in patients with trigeminal neuralgia. The carotid artery and derived aortic blood pressure waveforms were obtained using a pulse wave analysis system. The ratio of the pressure wave amplitude above the systolic shoulder to the total systolic blood pressure (augmentation index, AIx) was recorded. Thirty two patients with trigeminal neuralgia (16 male and 16 female) and 100 controls (50 male and 50 female) were recruited. Eleven patients had been treated by microvascular decompression, mean (SD) time from surgery 17 (24) months (range 3-86 months). For the patients with trigeminal neuralgia, the right and left carotid artery AIxs (mean (SD)) were 120.6 (21.7)% and 120.7 (19.1)% respectively. Corresponding values for the control group were 120.5 (19.3)% and 120.9 (19.5)%. The calculated AIx for the ascending aorta was 27.7 (10.1)% and 27.2 (10.5)% for the patients with trigeminal neuralgia and controls respectively. No significant differences were seen in either the right or left carotid artery (p=0.5 and p=0.6 respectively) or the derived ascending aorta (p=0.8). The results show that there does not seem to be a generalised increase in arterial stiffness in patients with trigeminal neuralgia.


Assuntos
Pressão Sanguínea/fisiologia , Artérias Carótidas/fisiopatologia , Neuralgia do Trigêmeo/diagnóstico , Neuralgia do Trigêmeo/fisiopatologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Aorta/fisiopatologia , Feminino , Hemodinâmica/fisiologia , Humanos , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes
10.
J Neurosurg ; 95(5): 764-70, 2001 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-11702865

RESUMO

OBJECT: Applanation tonometry is a noninvasive method of assessing both peripheral and central arterial blood pressure (BP) profiles. In this study the authors examine whether there are differences in these profiles in patients with intracranial aneurysms when compared with age-matched controls. METHODS: Carotid artery (CA) and derived aortic BP waveforms were obtained using a pulse wave analysis system. The ratio of the pressure wave amplitude above the systolic shoulder to the total systolic BP (augmentation index [AI]) was recorded. One hundred seventy-three patients with intracranial aneurysms (23 unruptured lesions) and 173 healthy control volunteers were examined. For the patients with aneurysms the right and left CA AIs (mean +/- standard deviation) were 125.6 +/- 23.1% and 128.3 +/- 22.1%, respectively. Corresponding values for the control group were 118.4 +/- 22.6% and 119.4 +/- 21.8%. The calculated AI for the ascending aorta was 29.8 +/- 10.5% and 25.6 +/- 12.2% for patients with aneurysms and control volunteers, respectively. Significant asymmetry in CA AI was seen in patients with aneurysms, the left being greater (p = 0.002). No significant differences were seen in mean BP (108 +/- 14 mm Hg in patients with aneurysms compared with 106 +/- 16 mm Hg in controls; p = 0.2). Multivariate analysis excluded the influence of BP and other potential confounding vascular risk factors for increased AI. CONCLUSIONS: Significant differences in AI, both in magnitude and symmetry, were identified in patients with intracranial aneurysms when compared with matched controls.


Assuntos
Hemodinâmica , Aneurisma Intracraniano/etiologia , Estresse Fisiológico/complicações , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Aorta/fisiopatologia , Pressão Sanguínea , Artérias Carótidas/fisiopatologia , Feminino , Humanos , Aneurisma Intracraniano/fisiopatologia , Masculino , Pessoa de Meia-Idade , Análise Multivariada , Pulso Arterial , Valores de Referência , Fatores de Risco , Sístole , Tonometria Ocular/métodos
11.
Comp Biochem Physiol B Biochem Mol Biol ; 126(3): 271-81, 2000 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-11007169

RESUMO

Canaries appear to be primarily seed-eaters, although there are no reports of their feeding ecology in the wild. In captivity, they are offered seed-based diets, preferring to consume seeds such as canary, rapeseed and millet. The mean daily dry-matter intake ranges from 3 to 4 g, which corresponds to a mean gross energy intake of approximately 70 kJ per bird per day. The efficiency of dietary metabolism is high (0.85), which equates to individual metabolizable energy intakes of 45-75 kJ per bird per day. For a canary of average body weight (22 g) the data can be fitted to a regression equation to predict a requirement of 62 kJ ME per day. This corresponds to published information on the energy requirements of other passerine species, but deviates from the predictive equation for poultry. The digestibility values for protein, fat and carbohydrate are similar to those obtained for the budgerigar, although it is likely that the digestibility coefficient is dependent upon the seed type and alimentary tract lipase and amylase activities. Nutrient requirements of canary chicks have not yet been determined, although recent studies have provided data on the nutrient intakes of developing chicks. The newly-hatched canary chick has a rapid growth rate, achieving 90% of its asymptotic body mass by 11 days of age. Gross energy intake is approximately 3 kJ per day following hatching and by day 10 is equivalent to that of an adult canary. It appears that the protein intake should lie between 16.5 and 21.9% of the diet (as is), with peak intake occurring between 8 and 10 days of age.


Assuntos
Canários/fisiologia , Animais , Dieta , Metabolismo Energético
12.
Pediatrics ; 106(2): E27, 2000 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-10920183

RESUMO

Tomisaku Kawasaki published the first English-language report of 50 patients with Kawasaki disease (KD) in 1974. Since that time, KD has become the leading cause of acquired heart disease among children in North America and Japan. Although an infectious agent is suspected, the cause remains unknown. However, significant progress has been made toward understanding the natural history of the disease and therapeutic interventions have been developed that halt the immune-mediated destruction of the arterial wall. We present a brief history of KD, review progress in research on the disease, and suggest avenues for future study. Kawasaki saw his first case of KD in January 1961 and published his first report in Japanese in 1967. Whether cases existed in Japan before that time is currently under study. The most significant controversy in the 1960s in Japan was whether the rash and fever sign/symptom complex described by Kawasaki was connected to subsequent cardiac complications in a number of cases. Pathologist Noboru Tanaka and pediatrician Takajiro Yamamoto disputed the early assertion of Kawasaki that KD was a self-limited illness with no sequelae. This controversy was resolved in 1970 when the first Japanese nationwide survey of KD documented 10 autopsy cases of sudden cardiac death after KD. By the time of the first English-language publication by Kawasaki in 1974, the link between KD and coronary artery vasculitis was well-established. KD was independently recognized as a new and distinct condition in the early 1970s by pediatricians Marian Melish and Raquel Hicks at the University of Hawaii. In 1973, at the same Hawaiian hospital, pathologist Eunice Larson, in consultation with Benjamin Landing at Los Angeles Children's Hospital, retrospectively diagnosed a 1971 autopsy case as KD. The similarity between KD and infantile periarteritis nodosa (IPN) was apparent to these pathologists, as it had been to Tanaka earlier. What remains unknown is the reason for the simultaneous recognition of this disease around the world in the 1960s and 1970s. There are several possible explanations. KD may have been a new disease that emerged in Japan and emanated to the Western World through Hawaii, where the disease is prevalent among Asian children. Alternatively, KD and IPN may be part of the spectrum of the same disease and clinically mild KD masqueraded as other diseases, such as scarlet fever in the preantibiotic era. Case reports of IPN from Western Europe extend back to at least the 19th century, but, thus far, cases of IPN have not been discovered in Japan before World War II. Perhaps the factors responsible for KD were introduced into Japan after the World War II and then reemerged in a more virulent form that subsequently spread through the industrialized Western world. It is also possible that improvements in health care and, in particular, the use of antibiotics to treat infections caused by organisms including toxin-producing bacteria reduced the burden of rash/fever illness and allowed KD to be recognized as a distinct clinical entity. Itsuzo Shigematsu, Hiroshi Yanagawa, and colleagues have conducted 14 nationwide surveys in Japan. These have indicated that: 1) KD occurred initially in nationwide epidemics but now occurs in regional outbreaks; 2) there are approximately 5,000 to 6,000 new cases each year; 3) current estimates of incidence rates are 120 to 150 cases per 100,000 children <5 years old; 4) KD is 1.5 times more common in males and 85% of cases occur in children <5 years old; and 5) the recurrence rate is low (4%). In 1978, David Morens at the Centers for Disease Control and Prevention published a case definition based on Kawasaki's original criteria. The Centers for Disease Control and Prevention developed a computerized database in 1984, and a passive reporting system currently exists in 22 states. Regional investigations and national surveys suggest an annual incidence of 4 to 15 cases per 100 000 children <5 years o


Assuntos
Síndrome de Linfonodos Mucocutâneos , Criança , Pré-Escolar , Progressão da Doença , Epônimos , Feminino , Saúde Global , História do Século XX , Humanos , Incidência , Japão/epidemiologia , Masculino , Síndrome de Linfonodos Mucocutâneos/epidemiologia , Síndrome de Linfonodos Mucocutâneos/etiologia , Síndrome de Linfonodos Mucocutâneos/história , Síndrome de Linfonodos Mucocutâneos/terapia , Estados Unidos/epidemiologia
13.
Reprod Nutr Dev ; 40(3): 249-60, 2000.
Artigo em Inglês | MEDLINE | ID: mdl-10943604

RESUMO

The ability of the growing kitten to digest protein, fat, carbohydrate, dry-matter and energy were assessed. Kittens were divided into two groups; one group was fed a wet diet, the other a dry diet. Both groups were allowed ad libitum access to food. Apparent digestibility of the two diets, and kitten bodyweights were measured over a 24-week period. There were no significant differences in mean bodyweight between the two groups. Digestible energy intake of the kittens decreased with increased age; regression analysis of the data generated two fitted models which appeared to accurately predict the digestible energy intake between 39 and 41 weeks of age. There was a significant (P < 0.05) effect of diet on the apparent digestibility of protein, organic-matter and dry-matter. Age had a significant (P < 0.05) effect on the apparent digestibility of all the parameters measured. Newman-Keuls multiple range tests showed that apparent digestibility of carbohydrate, organic-matter and total energy significantly (P < 0.05) increased in kittens older than 19 weeks. This suggests that the digestive capacity of the younger cat may be affected by the physiological development of the gut, and dietary induced enzyme modulation.


Assuntos
Envelhecimento , Gatos/crescimento & desenvolvimento , Digestão/fisiologia , Animais , Gatos/fisiologia , Proteínas Alimentares/administração & dosagem , Ingestão de Energia , Feminino , Intestinos/enzimologia , Intestinos/crescimento & desenvolvimento , Masculino , Análise de Regressão , Especificidade da Espécie , Aumento de Peso
14.
J Neurol Neurosurg Psychiatry ; 68(4): 489-95, 2000 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-10727486

RESUMO

OBJECTIVE: To assess transcranial power Doppler and the effect of an intravenous ultrasonic contrast agent for detecting intracranial aneurysms in patients admitted with a subarachnoid haemorrhage METHODS: 203 patients with subarachnoid haemorrhage were examined with the operator blind to the results of the admission CT and subsequent digital subtraction angiogram (DSA). In 98 cases patients were imaged using unenhanced transcranial power Doppler, and in 105 cases, patients were imaged both using unenhanced and echo contrast enhanced (Levovist, Schering AG) transcranial power Doppler. RESULTS: DSA detected 168 intracranial aneurysms in 128 patients (24 patients had multiple lesions) and 75 patients had an aneurysm negative DSA. There was agreement between DSA and transcranial power Doppler in 87 intracranial aneurysms of which 20 were only detected after infusion of contrast agent. Without contrast infusion, transcranial power Doppler showed a sensitivity of 40% and specificity of 91%. A significant increase in detection was noted when using a contrast agent (chi(2) = 9.49, p<0.001). With a contrast study the sensitivity increase to 55% with a specificity of 83%. Intracranial aneurysm detection by transcranial power Doppler was significantly dependent on position using a contrast infusion (chi(2) = 15.87, p<0.05). A positive correlation was also found between the size of intracranial aneurysms measured by transcranial power Doppler and DSA (r = 0.55, p<0.05). The transcranial power Doppler sensitivity and specificity increased with larger aneurysms and reached 100% for intracranial aneurysms greater than 12 mm diameter. Detection by transcranial power Doppler was also dependent on morphology (chi(2) = 14.46, p<0.001). CONCLUSIONS: The detection of intracranial aneurysm by transcranial power Doppler is dependent on aneurysm location, size, and morphology and is enhanced with the use of an intravenous contrast agent.


Assuntos
Meios de Contraste , Aneurisma Intracraniano/diagnóstico por imagem , Adulto , Idoso , Idoso de 80 Anos ou mais , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Ultrassonografia
15.
Ecol Appl ; 3(1): 175-186, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27759215

RESUMO

Production of tallgrass prairie vegetation was measured on experimental plots in which defoliation intensity and frequency were manipulated by mowing and using movable exclosures on areas chronically grazed by cattle. Defoliation history largely controlled whether or not defoliated plants overcompensated (exhibited enhanced production compared to undefoliated controls) for tissue removal. Plants on chronically grazed sites only compensated for foliage removed by grazers. Production on plots mowed prior to the year of measurement was similar to that on chronically grazed sites, while previously unmowed plots exhibited substantial aboveground overcompensation. Aboveground production was maximized by the most frequent mowing treatment and by intermediate mowing heights. Nitrogen and phosphorus concentrations and amounts in aboveground tissues were increased by mowing and grazing. Current mowing regime was more important than mowing history in determining nitrogen concentrations except very early in the growing season. Effects of grazing and mowing on belowground biomass were inconsistent, but frequent mowing appeared to limit accumulation of belowground N reserves and biomass. In North American grasslands, overcompensation is a nonequilibrium plant response to grazing. Photosynthate that would be stored as reserves and used for root growth and flower and seed production instead is used to replace lost leaf area, thereby resulting in higher foliage productivity. However, under chronic grazing or mowing, vegetation is prevented from maintaining high nutrient and water uptake capacity (large root biomass) and accumulating reserves that allow overcompensation responses.

16.
Ecol Appl ; 3(1): 10-16, 1993 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27759222

RESUMO

We argue that herbivores often induce nonlinear or biphasic growth and development in plants. Collectively these individual responses translate into a system-level optimization curve wherein at low levels of herbivory overall community responses show increases in production potential, whereas extreme herbivory causes extreme reduction in productivity. The transition between these two states defines a point of optimal herbivory in respect to C and N processes.We present four case examples from the literature demonstrating such nonlinear responses, suggesting a widespread existence for this herbivore-plant phenomenon. The nonlinear responses appear to demonstrate temporal and spatial scale dependencies.

17.
Eur J Clin Pharmacol ; 43(4): 341-5, 1992.
Artigo em Inglês | MEDLINE | ID: mdl-1451711

RESUMO

The possibility has been investigated that, after admission to hospital with acute upper gastrointestinal bleeding, patients who have been users of aspirin and non-aspirin non-steroidal anti-inflammatory drugs have poorer baseline renal function, a greater improvement in renal function during their hospital stay, and a larger transfusion requirement than non-users. Patients over 50 years of age admitted to public hospitals with acute upper gastrointestinal bleeding were studied. Creatinine clearance was estimated from serum creatinine and the transfusion requirement was recorded as the number of units of blood transfused on Day 1 and throughout the entire hospital stay. Data were obtained prospectively from case notes and by structured interview. Users of non-steroidal anti-inflammatory drugs were significantly older than non-users. The estimated creatinine clearance on admission to hospital declined with age. Creatinine clearance was 13.2 (95% CI 6.0 to 20.4) ml.min-1 lower in users than non-users of non-aspirin non-steroidal anti-inflammatory drugs. However, the difference was attributable to the older age of the drug users rather than to the drugs themselves. On average, the increase in creatinine clearance during hospital stay was the same in users and non-users of non-aspirin non-steroidal anti-inflammatory drugs. Prior use of aspirin had no effect on any measure of renal function. The incidence of blood transfusion was higher in older than in younger patients but neither the incidence of transfusion, nor the transfusion requirement, was different between users and non-users of non-aspirin non-steroidal anti-inflammatory drugs and aspirin.(ABSTRACT TRUNCATED AT 250 WORDS)


Assuntos
Anti-Inflamatórios não Esteroides/uso terapêutico , Aspirina/uso terapêutico , Transfusão de Sangue , Hemorragia Gastrointestinal/fisiopatologia , Rim/fisiopatologia , Idoso , Idoso de 80 Anos ou mais , Creatinina/sangue , Feminino , Hemorragia Gastrointestinal/sangue , Hemorragia Gastrointestinal/terapia , Humanos , Rim/efeitos dos fármacos , Masculino , Pessoa de Meia-Idade
18.
Ecol Appl ; 1(4): 443-452, 1991 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-27755674

RESUMO

Experiments were conducted to examine the potential role of grazing on ecosystem-level parameters as part of the NASA-sponsored First Isabela (International Satellite Land Surface Climatology Programmed) Field Experiment (FIFE) conducted at Konza Prairie Research Natural Area in 1987. Here we report results of one experiment conducted in a field consisting primarily of Bromus inermis, a cool season C3 grass. The experiment involved four simulated grazing components (unmowed control, 20-, 10-, and 5-cm mowing heights) and fertilization (untreated control and ammonium nitrate application). The plots were mowed to ground level and raked in April, following which they were mowed seven times during the growing season from May to October. Biomass production, N production, and spectral reflectance data were collected with a hand-held radiometer throughout the growing season, with standing crop estimates taken at two periods (7 August [day 219] and 27 October [day 300]) to correlate with the remote sensing information base. Standing crop values of mowed plots were as much as 67-70% lower than controls, but they produced significantly larger amounts of both biomass and total N. Maximum seasonlong production values in the mowed plots were °43% above controls, with major differences developing as a result of fertilization. Fertilized plots produced 67% more foliage than unfertilized plots. Our data show over-compensatory growth as a result of the simulated grazing treatments. Indexes (NDVI [normalized difference vegetation index] and greenness) derived from the reflectance data were poorly correlated with biomass. The correlation of NDVI with N content of the canopy foliage was somewhat stronger, particularly if stratified by mowing class. NDVI was a better predictor of vegetation status than the greenness indexes, but in plots stimulating heavily grazed areas where leafy vegetation was sparse and soil became more visible from above the canopy its utility decreased significantly.

19.
Can J Biochem ; 59(2): 100-5, 1981 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-6786712

RESUMO

Beta-Galactosidase was found to act on alpha-lactose slightly more than twice as rapidly as on beta-lactose for both the hydrolysis and transgalactosylis reactions. The effect was shown to be on the Vmax values; the Km values for the different anomeric forms were the same. The step of the reaction for which the enzyme has anomeric specificity was shown to be glycosidic bond breakage. The steps in glucose release or in the glucose acceptor reaction were not affected by anomeric composition. Neither allolactose hydrolysis nor transport of lactose into the cells by lac permease was sensitive to the anomeric composition of the substrate. The implications of these results for lac operon induction and for lactose metabolism are discussed.


Assuntos
Proteínas de Escherichia coli , Escherichia coli/enzimologia , Galactosidases/metabolismo , Proteínas de Membrana Transportadoras/metabolismo , Proteínas de Transporte de Monossacarídeos , Simportadores , beta-Galactosidase/metabolismo , Glucose , Cinética , Lactose , Nitrofenilgalactosídeos , Estereoisomerismo , Especificidade por Substrato
20.
Biochemistry ; 19(19): 4534-8, 1980 Sep 16.
Artigo em Inglês | MEDLINE | ID: mdl-6250587

RESUMO

Differential scanning calorimetry has been used to study the thermal denaturation of ribonuclease in aqueous dimethyl sulfoxide and acqueous p-dioxane. A two-state reversible denaturation occurs in acqueous dimethyl sulfoxide. The denaturation is irreversible in aqueous p-dioxane. The transition temperatuire decreases in both organic solvents, with p-dioxane producing a considerably greater effect. The enthalpy of the denaturation initially increases with increasing dimethyl sulfoxide concentration and then decreases at high concentrations. Similar behavior is observed in the entropy in the dimethyl sulfoxide solutions. The enthalpy of the denaturation decreases markedly with low p-dioxane concentrations. Changes in pH due to presence of organic solvent cannot account for the changes in enthalpy of denaturation. Addition of organic solvent tends to increase the pH of the ribonuclease solution. Higher pH in aqueous solutions gives a high transition temperature, whereas addition of organic solvent results in the opposite bahavior. The relative changes in the two solvents systems suggest that specific solvent effects occur and that destablization of the native state relative to the denatured state is greater with p-dioxane than with dimethyl sulfoxide.


Assuntos
Dimetil Sulfóxido , Dioxanos , Dioxinas , Endonucleases , Ribonucleases , Animais , Bovinos , Concentração de Íons de Hidrogênio , Músculo Liso Vascular/metabolismo , Conformação Proteica , Desnaturação Proteica , Ribonuclease Pancreático , Solventes , Termodinâmica
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