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1.
BMC Endocr Disord ; 24(1): 33, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38462602

RESUMO

PURPOSE: To analyze the prevalence and progression of fulminant type 1 diabetes (FT1D) in Qatar. METHODS: This retrospective study analyzed consecutive index- diabetic ketoacidosis (DKA) admissions (2015-2020) among patients with new-onset T1D (NT1D) in Qatar. RESULTS: Of the 242 patients, 2.5% fulfilled the FT1D diagnostic criteria. FT1D patients were younger (median-age 4-years vs.15-years in classic-T1D). Gender distribution in FT1D was equal, whereas the classic-T1D group showed a female predominance at 57.6% (n = 136). FT1D patients had a mean C-peptide of 0.11 ± 0.09 ng/ml, compared to 0.53 ± 0.45 ng/ml in classic-T1D. FT1D patients had a median length of stay (LOS) of 1 day (1-2.2) and a DKA duration of 11.25 h (11-15). The median (length of stay) LOS and DKA duration in classic-T1D patients were 2.5 days (1-3.9) and 15.4 h (11-23), respectively. The FT1D subset primarily consisted of moderate (83.3%) and severe 916.7%) DKA, whereas classic T1D had 25.4% mild, 60.6% moderate, and 14% severe DKA cases. FT1D was associated with a higher median white cell count (22.3 × 103/uL) at admission compared to classic T1D (10.6 × 103/uL). ICU admission was needed for 66.6% of FT1D patients, compared to 38.1% of classic-T1D patients. None of the patients in the FT1D group had mortality, while two died in the classic-T1D group. CONCLUSION: This is the first study establishing the existence of FT1D in ME, which presented distinctively from classic-T1D, exhibiting earlier age onset and higher critical care requirements. However, the clinical outcomes in patients with FT1D seem similar to classic T1D.


Assuntos
Diabetes Mellitus Tipo 1 , Cetoacidose Diabética , Humanos , Feminino , Pré-Escolar , Masculino , Diabetes Mellitus Tipo 1/diagnóstico , Diabetes Mellitus Tipo 1/epidemiologia , Diabetes Mellitus Tipo 1/complicações , Estudos Retrospectivos , Prevalência , Cetoacidose Diabética/diagnóstico , Cetoacidose Diabética/epidemiologia , Cetoacidose Diabética/complicações , Prognóstico , Oriente Médio/epidemiologia
2.
Qatar Med J ; 2022(3): 39, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35974886

RESUMO

BACKGROUND: COVID-19 infection has been spreading across the globe since the end of 2019, and it continues to cause chronic multi-system sequelae, of which thyroid dysfunction appears to be the major one. We have discussed here 10 cases of thyroid dysfunction after COVID-19 infection. METHODS: Case series report. From October 2020 to July 2021, a series of 10 cases of thyroid dysfunction after COVID-19 infection were recorded and managed in a single outpatient endocrine center in Doha, Qatar. CASES PRESENTATION: We have reported 5 cases of Graves's hyperthyroidism, 2 of chronic primary hypothyroidism (including one with Grave's disease [GD]) who was treated through radioactive iodine (RAI) therapy, one case of subacute thyroiditis, one case with "Sick euthyroid disease," and one case of central hypothyroidism. Presently, patients with GD are being treated with carbimazole and those with hypothyroidism are being treated with levothyroxine. The remaining patients had recovered with euthyroid. CONCLUSION: This is the largest case series reported from a single center to date. The findings of this series indicate a bimodal distribution of thyroid dysfunction in patients with COVID-19 infection. A review of the literature and discussion of potential pathophysiological mechanisms has been presented. We have emphasized the importance of screening for thyroid dysfunction in "post-COVID-19" cases, considering that the prevalence may be underestimated.

3.
EClinicalMedicine ; 72: 102605, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38680518

RESUMO

Background: Diabetes in pregnancy (DIP) is associated with adverse fetal and maternal outcomes. DIP is classified as either pre-existing or new-onset diabetes mellitus (DM), which is classified into gestational DM (GDM) and newly detected type 2 (N-T2D). All pregnant women in Qatar who are not known to have pre-existing DM are offered screening for DIP during the first antenatal care visit and after 24 weeks gestation. The study aims to report the DIP screening rates, the prevalence of DIP, and the impact of the universal screening program on adverse pregnancy outcomes. Methods: This retrospective study included all women who gave birth in Hamad Medical Corporation (HMC) hospitals between 2019 and 2022. New-onset DIP was defined using the WHO-2013 criteria. The primary outcomes were the screening rates and the prevalence of DIP in Qatar. The secondary outcomes were the difference in preterm delivery, C-section, macrosomia, large for gestational age (LGA), small for gestational age (SGA), and intra-uterine fetal death (IUFD) between women with or without GDM. Findings: We included 94,422 women who gave birth to 96,017 neonates (85.7%) out of 112,080 neonates born nationwide. The number of women with pre-existing diabetes was 2496 women. Of 91,926 eligible women, 77,372 (84.2%) were screened for DIP. The prevalence of GDM is 31.6% (95% CI: 31.3-32.0%); N-T2D is 2.2% (95% CI: 2.1-2.3%), and pre-existing Type 2 DM and Type 1 DM was 2.6% (95% CI: 0.8-3.0%) and 0.2% (0.19-0.25), respectively. Compared to the non-GDM group, women with GDM were older (30.8 ± 5.3 versus 29.7 ± 5.2 years, p < 0.001). After adjusting for age, women with GDM had lower risk of IUFD and SGA (0.63 [95% CI 0.50-0.80, p < 0.001], 0.88 [95% CI 0.84-0.92, p < 0.001] respectively) but higher risk of C-section and LFD (1.07 [95% CI 1.04-1.10, p < 0.001], 1.09 [95% CI 1.01-1.15, p = 0.01], respectively, compared to women with no-GDM. Interpretation: Of the women eligible for screening, 84.2% were screened by the DIP program in Qatar. The prevalence of DIP in Qatar is 36.9%. Integrated care is critical for the screening and management of diabetes during pregnancy. Fundings: The authors did not receive any funding for this project.

4.
Reprod Sci ; 31(7): 2073-2079, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38485893

RESUMO

Over the years, several international guidelines have been developed by specialist organizations for the diagnosis of gestational diabetes mellitus (GDM). However, these guidelines vary and lack consensus on what level of glycemia defines GDM and worryingly, there is now evidence of over- or- under-diagnosis of women with GDM by current criteria. Towards this end, the National Priorities Research Program (NPRP) funded a program of research aimed at elucidating the problem with GDM diagnosis. It was determined, on completion of the project, that the solution required diagnosis of graded levels of dysglycemia in pregnancy and not just a diagnosis of presence or absence of GDM. A new diagnostic criterion (called the NPRP criterion) was created based on a single numerical summary of the three readings from the oral glucose tolerance test (GTT) that diagnosed women in pregnancy into four levels: normal, impaired, GDM and high risk GDM. This paper now examines existing GDM criteria vis-à-vis the NPRP criterion. It is noted that no significant change has happened over the years for existing criteria except for a gradual reduction in the threshold values of individual time-points or the number of time points, bringing us towards over-diagnosis of GDM in pregnancy. The new criterion unifies all readings from the GTT into one numerical value and, because it results in four levels of glycemia, represents a new way forwards for GDM diagnosis and can potentially reduce the rates of under diagnosis and over diagnosis of GDM.


Assuntos
Diabetes Gestacional , Teste de Tolerância a Glucose , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/sangue , Humanos , Feminino , Gravidez , Glicemia/metabolismo , Glicemia/análise , Guias de Prática Clínica como Assunto
5.
Indian Heart J ; 65(3): 315-8, 2013.
Artigo em Inglês | MEDLINE | ID: mdl-23809388

RESUMO

Torsades de pointes ("twisting of points") (TdP) is a broad complex tachyarrhythmia which was first described in 1966 by Francois Dessertenne and usually results from prolongation of the QT interval.(1) A wide variety of drugs have been shown to prolong the QT interval in susceptible individuals.(2) We present the case of a former intravenous heroin user presenting with several episodes of TdP which were caused by QT prolongation due to methadone treatment and exacerbated by hepatitis B/C infection. Despite aggressive medical treatment and withdrawal of methadone, he had recurrent episodes of TdP which required continuous temporary cardiac pacing for six days. He was found to have moderate LV dysfunction on his echocardiogram and unobstructed coronary arteries on coronary angiography. He underwent implantation of a defibrillator due to concerns about further episodes of ventricular arrhythmias which could recur even in the absence of further methadone use.


Assuntos
Analgésicos Opioides/efeitos adversos , Cardioversão Elétrica , Metadona/efeitos adversos , Torsades de Pointes/induzido quimicamente , Torsades de Pointes/terapia , Adulto , Analgésicos Opioides/administração & dosagem , Desfibriladores Implantáveis , Eletrocardiografia , Humanos , Masculino , Metadona/administração & dosagem , Tratamento de Substituição de Opiáceos , Torsades de Pointes/complicações , Desequilíbrio Hidroeletrolítico/complicações , Desequilíbrio Hidroeletrolítico/terapia
6.
Cureus ; 14(5): e24814, 2022 May.
Artigo em Inglês | MEDLINE | ID: mdl-35686265

RESUMO

Background and objective Among the common endocrinological disorders of pregnancy, thyroid disorders rank second after diabetes. Thyroid autoimmunity is linked to sub-fertility, miscarriages, preterm birth, gestational diabetes, and adverse neurodevelopmental sequelae in children. Peroxidase and thyroglobulin autoantibodies may be associated with enhanced global autoimmune state, which may have adverse effects on the fetal or placental development. It is the main cause of hypothyroidism in reproductive-age women and is associated with poor obstetric outcomes. In Gulf countries, a higher prevalence of thyroid antibodies during pregnancy was reported. However, there is paucity of data in the literature in the Gulf countries in this regard. Our study was conducted to assess the effects of thyroid antibodies on adverse maternal and neonatal outcomes in pregnancy in a multiethnic population of Qatar. The study aimed to assess the prevalence of thyroid antibodies in pregnant hypothyroid women and their impact on adverse fetal outcomes in pregnancy. Design A Retrospective study of patients' notes (retrospective chart review) was conducted at a secondary hospital in Qatar. Records of the women who delivered from January 2017 to June 2018 were evaluated. A total of 384 women were included after applying exclusion criteria. Neonatal outcomes were compared in hypothyroid women with (group A1) and without thyroid antibodies (group A2) and were compared with euthyroid women (group B). Statistical analysis was performed using SPSS Statistics version 27.0 (Armonk, NY: IBM Corp). Results A total of 7978 women delivered during the study period and the prevalence of hypothyroidism in our sample was 3.47%; 33.33% had thyroid antibodies. Women with more than one miscarriage were 30% (odds ratio {OR}: 2.06, 95% confidence interval {CI}: 1.112-3.811, p<0.05), 21.24% (OR: 1.20, 95% CI: 0.676-2.115, p>0.05), and 17% in group A1, A2, and B, respectively. The incidence of preterm births was 10% (OR: 2.22, 95% CI: 0.760-6.495, p>0.05), 4.23% (OR: 0.94, 95% CI: 0.308-2.876, p>0.05), and 4.5% in groups A1, A2, and B, respectively. Small for gestational age infants were 10% (OR: 3.33, 95% CI: 1.036-10.71, p<0.05), 5.93% (OR: 1.97, 95% CI: 0.640-6.023, p>0.05), and 3% in groups A1, A2, and B, respectively. The study revealed an association between thyroid antibodies and adverse maternal and neonatal outcomes in pregnancy. Conclusion Thyroid autoimmunity is associated with poor fetal outcomes. In Gulf countries with higher prevalence of endocrinological disorders (obesity and diabetes), thyroid disorders need attention. As fewer studies were reported from these areas with limited results in literature, this study gives an insight into the prevalence of thyroid disorders, thyroid antibodies, and their association with pregnancy outcomes.

7.
Clin Case Rep ; 10(4): e05680, 2022 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-35414931

RESUMO

Diabetic ketoacidosis (DKA) is a life-threatening complication of diabetes and is considered a medical emergency. Euglycemic DKA (EKDA) is a variant of DKA with a normal or minimally elevated glucose level <200 mg/dl. The condition can be difficult to diagnose due to the relatively normal glucose levels. Pregnancy, infection, and a low-calorie intake are some of the contributing common etiologies of EDKA. Despite a rapid increase in scientific publications on COVID-19, there are still knowledge gaps regarding the course of COVID-19 in some patient subset. This is especially the case for pregnant women. In this case report, we discuss the course of COVID-19 infection in a pregnant woman with gestational diabetes who developed severe euglycemic diabetic ketoacidosis triggered by various precipitating factors, including starvation, caused by COVID-19 infection and its gastrointestinal effects.

8.
Prim Care Diabetes ; 16(1): 96-101, 2022 02.
Artigo em Inglês | MEDLINE | ID: mdl-34419366

RESUMO

AIMS: Disagreement about the appropriate criteria for the diagnosis of gestational diabetes mellitus (GDM) persists. This study examines an alternative approach which combines information from all time-points on the glucose tolerance test (GTT) into a single index and expands the GDM spectrum into four categories using data from three geographically and ethnically distinct populations. METHODS: A retrospective observational study design was used. Data from Wisconsin, USA (723 women) was used in derivation of the criterion and data from Doha, Qatar (1284 women) and Cape Town, South Africa (220 women) for confirmation. Pregnant women without pre-existing diabetes with a GTT done between 23 and 30 weeks gestation were included. A novel index was derived from the GTT termed the weighted average glucose (wAG). This was categorized into four pre-defined groups (henceforth National Priorities Research Program (NPRP) criterion); i) normal gestational glycemia (NGG), ii) impaired gestational glycemia (IGG), iii) GDM and iv) high risk GDM (hGDM). RESULTS: In the Doha cohort, compared to the NGG group, the odds of large for gestational age babies increased 1.33 fold (P = 0.432), 2.86 fold (P < 0.001) and 3.35 fold (P < 0.001) in the IGG, GDM and hGDM groups respectively. The odds of pregnancy induced hypertension increased 2.10 fold (P = 0.024) in GDM & hGDM groups compared to the IGG and NGG groups. In the Cape Town cohort, a third of women in the GDM group and two-thirds in the hGDM group progressed to T2DM at 5 years. CONCLUSIONS: The NPRP categorization identifies four distinct risk clusters of glycemia in pregnancy which may aid better decision making in routine management, avoid potential over-diagnosis of women at lower risk of complications and assist with diabetes prevention in women at high-risk after an index pregnancy with GDM.


Assuntos
Diabetes Gestacional , Glicemia , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/epidemiologia , Feminino , Teste de Tolerância a Glucose , Humanos , Gravidez , Estudos Retrospectivos , África do Sul/epidemiologia
9.
Sci Rep ; 11(1): 5604, 2021 03 10.
Artigo em Inglês | MEDLINE | ID: mdl-33692395

RESUMO

There are currently several diagnostic criteria for gestational diabetes (GDM). Both the WHO -2013 and NICE diagnose GDM based on a single step 75 g OGT; however; each uses different glucose thresholds. Previous studies have shown that the prevalence of GDM using the NICE criteria (GDM-N) is lower than that using the WHO-2013 criteria (GDM-W). Qatar has national diabetes in pregnancy program in which all pregnant women undergo OGTT screening using the WHO-2013 criteria. This study aims to define the prevalence of GDM using both criteria in a high-risk population. This retrospective study included 2000 women who underwent a 75 g (OGTT) between Jan 2016 and Apr 2016 and excluded patients with known pre-conception diabetes, multiple pregnancy, and those who did not complete the OGTT. We then classified the women into GDM-W positive, GDM-N positive but GDM-W negative, and normal glucose tolerance (NGT) population. A total of 1481 women (74%) had NGT using the NICE or the WHO-2013 criteria. The number of patients who met both criteria was 279 subjects (14%) with a good agreement (Kappa coefficient 0.67, p < 0.001). The NICE and the WHO-2013 criteria were discordant in 240 subjects (12% of the cohort); 6.7% met the WHO -2013 criteria only and only 5.3% met the NICE criteria. The frequency of pre-eclampsia, pre-term delivery, Caesarean-section, LGA and neonatal ICU admissions were significantly increased in the GDM-W group. However, the GDM-N positive but GDM-W negative had no increased risk of maternal or fetal complications apart from pregnancy-induced hypertension. The WHO-2013 and the NICE criteria classified a similar proportion of pregnant women, 21.5% and 20.1%, respectively, as having GDM; however, they were concordant in only 14% of the cases. Women who are GDM-N positive but GDM-W negative are not at increased risk of maternal and fetal pregnancy complications, except for pregnancy-induced hypertension. As the NICE criteria are more specific to the UK population, we would recommend the use of the WHO-2013 criteria to diagnose GDM in the MENA region and possibly other regions that do not have the same set-up as the UK.


Assuntos
Diabetes Gestacional , Programas de Rastreamento , Pré-Eclâmpsia , Adulto , Diabetes Gestacional/diagnóstico , Diabetes Gestacional/epidemiologia , Diabetes Gestacional/fisiopatologia , Feminino , Humanos , Pré-Eclâmpsia/diagnóstico , Pré-Eclâmpsia/epidemiologia , Pré-Eclâmpsia/fisiopatologia , Gravidez , Prevalência , Estudos Retrospectivos , Organização Mundial da Saúde
10.
J Cardiovasc Nurs ; 23(4): 364-70, 2008.
Artigo em Inglês | MEDLINE | ID: mdl-18596501

RESUMO

OBJECTIVE: Despite the importance of health-related quality of life (HRQL) as an outcome measure in chronic heart failure (CHF), instruments currently available have been developed by clinicians or researchers; none have been derived from the patient's perspective. The purpose of this study was to develop and validate a patient-derived, disease-specific HRQL measure. METHODS: The psychometric testing of the Chronic Heart Failure Assessment Tool (CHAT) followed 2 phases: testing the psychometric properties (n = 223) of the 51-item version of the CHAT in a postal survey and validation of the CHAT (n = 68) using the Medical Outcomes Study 36-Item Short-Form Health Survey and the Minnesota Living With Heart Failure questionnaire. RESULTS: The CHAT contains questions measuring 7 themes of HRQL: physical ability, emotional state, self-perception, relationships, coping with symptoms, maintaining social/lifestyle status, and cognitive aspects in respect to CHF. Factor analysis was used to analyze these themes. Four domains emerged: symptoms, activity levels, psychosocial aspects, and emotions. CONCLUSION: The CHAT comprises dimensions of HRQL identified by patients in the study population that may more appropriately reflect the concerns of patients. Further work is recommended to develop this tool for use as an HRQL measure in a CHF population.


Assuntos
Atitude Frente a Saúde , Insuficiência Cardíaca/psicologia , Avaliação em Enfermagem/métodos , Assistência Centrada no Paciente , Qualidade de Vida/psicologia , Inquéritos e Questionários/normas , Atividades Cotidianas/psicologia , Adulto , Idoso , Idoso de 80 Anos ou mais , Emoções , Análise Fatorial , Feminino , Indicadores Básicos de Saúde , Insuficiência Cardíaca/enfermagem , Humanos , Estilo de Vida , Masculino , Pessoa de Meia-Idade , Avaliação em Enfermagem/normas , Pesquisa em Avaliação de Enfermagem , Psicometria , Autoimagem , Índice de Gravidade de Doença , Estatísticas não Paramétricas , Reino Unido
11.
BMC Res Notes ; 11(1): 426, 2018 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-29970197

RESUMO

OBJECTIVE: The debate still continues about the preferred modality of treatment of gestational diabetes requiring pharmacological treatment. Insulin was previously considered as the gold standard, but the National Institute of Health and Care Excellence now recommend metformin as the first line drug of choice. The pharmacological management of gestational diabetes mellitus in the Middle East with its high risk population has not been widely published. We aim to evaluate the safety and efficacy of using metformin in comparison to insulin, in our group of patients, and to study key associated morbidities. RESULTS: A total of 291 women registered in the clinic during the study period. One hundred and twenty-one (121) were women with gestational diabetes Mellitus requiring medical therapy. Among them, 107 delivered at term. Ninety (84%) women received metformin. Additional insulin was required in 32% of these patients. There was a significant difference in the birth weight of babies in the metformin with insulin group of 207 g (p value 0.04) in favour of metformin. There was no significant difference in maternal or neonatal morbidities between the groups. Metformin was thus found to be a safe, practical and cost effective medication to be offered to our population.


Assuntos
Diabetes Gestacional/tratamento farmacológico , Hipoglicemiantes/uso terapêutico , Insulina/uso terapêutico , Metformina/uso terapêutico , Adulto , Feminino , Humanos , Oriente Médio , Gravidez , Resultado da Gravidez , Estudos Prospectivos , Catar , Adulto Jovem
12.
Eur J Heart Fail ; 7(4): 572-82, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15921797

RESUMO

The modern management of chronic heart failure has led to improved life expectancy, functioning and health-related quality of life (HRQL). HRQL measures the effects of an illness or a treatment from the patient's perspective. It is now recognised that the patient's perspective is as legitimate and valid as the clinician's in monitoring health care outcomes. Although there are a number of quality-of-life measures, which can be separated into two types-generic and disease specific-many have been developed, with little or no account being taken of the patient's perspective. Because most of the widely used measures are not patient centred, they may lack sensitivity and specificity in determining those aspects of HRQL important to individual patients. This paper reviews the use of quality-of-life assessment tools in the evaluation of patients with heart failure.


Assuntos
Indicadores Básicos de Saúde , Insuficiência Cardíaca , Qualidade de Vida , Humanos , Reprodutibilidade dos Testes , Sensibilidade e Especificidade , Perfil de Impacto da Doença , Inquéritos e Questionários , Resultado do Tratamento
13.
PLoS One ; 10(11): e0142045, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-26571120

RESUMO

OBJECTIVE: To investigate the prognostic effect of newly diagnosed diabetes mellitus (NDM) and impaired glucose tolerance (IGT) post myocardial infarction (MI). RESEARCH DESIGN AND METHODS: Retrospective cohort study of 768 patients without preexisting diabetes mellitus post-MI at one centre in Yorkshire between November 2005 and October 2008. Patients were categorised as normal glucose tolerance (NGT n = 337), IGT (n = 279) and NDM (n = 152) on pre- discharge oral glucose tolerance test (OGTT). Primary end-point was the first occurrence of major adverse cardiovascular events (MACE) including cardiovascular death, non-fatal MI, severe heart failure (HF) or non-haemorrhagic stroke. Secondary end-points were all cause mortality and individual components of MACE. RESULTS: Prevalence of NGT, impaired fasting glucose (IFG), IGT and NDM changed from 90%, 6%, 0% and 4% on fasting plasma glucose (FPG) to 43%, 1%, 36% and 20% respectively after OGTT. 102 deaths from all causes (79 as first events of which 46 were cardiovascular), 95 non fatal MI, 18 HF and 9 non haemorrhagic strokes occurred during 47.2 ± 9.4 months follow up. Event free survival was lower in IGT and NDM groups. IGT (HR 1.54, 95% CI: 1.06-2.24, p = 0.024) and NDM (HR 2.15, 95% CI: 1.42-3.24, p = 0.003) independently predicted MACE free survival. IGT and NDM also independently predicted incidence of MACE. NDM but not IGT increased the risk of secondary end-points. CONCLUSION: Presence of IGT and NDM in patients presenting post-MI, identified using OGTT, is associated with increased incidence of MACE and is associated with adverse outcomes despite adequate secondary prevention.


Assuntos
Diabetes Mellitus/diagnóstico , Teste de Tolerância a Glucose , Infarto do Miocárdio/complicações , Infarto do Miocárdio/diagnóstico , Adulto , Idoso , Glicemia/análise , Complicações do Diabetes/diagnóstico , Diabetes Mellitus/sangue , Feminino , Intolerância à Glucose/complicações , Humanos , Masculino , Pessoa de Meia-Idade , Infarto do Miocárdio/mortalidade , Admissão do Paciente , Prevalência , Prognóstico , Modelos de Riscos Proporcionais , Estudos Retrospectivos , Resultado do Tratamento
14.
Appl Biochem Biotechnol ; 98-100: 177-89, 2002.
Artigo em Inglês | MEDLINE | ID: mdl-12018246

RESUMO

Virtually all members of the order Thermotogales have demonstrated the ability to produce hydrogen; however, some members of this order produce considerably greater quantities than others. With one representative of this order, Thermotoga neapolitana, we have consistently obtained accumulation of 25-30% hydrogen with 12-15% carbon dioxide as the only other prominent product in the batch reaction. In contradistinction to information widely disseminated in the literature, we have also found that most members of this order tolerate and appear to utilize the moderate amounts of oxygen present in the gaseous phase of batch reactors (6-12%), with no apparent decrease in hydrogen production. Hydrogen accumulation has been widely reported to inhibit growth of Thermotogales. While this may be true at very high hydrogen tensions, we have observed log phase bacterial morphology (rods) even in the presence of 25-35% hydrogen concentrations. To maximize hydrogen production and minimize production of hydrogen sulfide, inorganic sulfur donors are avoided and the cysteine concentration in the medium is increased. We and others have demonstrated that different members of the order Thermotogales utilize a wide variety of feedstocks, including complex carbohydrates and proteins. Thus, it appears that organisms within this order have the potential to utilize a variety of organic wastes and to cost-effectively generate hydrogen.


Assuntos
Bacilos Gram-Negativos Anaeróbios Retos, Helicoidais e Curvos/metabolismo , Hidrogênio/metabolismo , Dióxido de Carbono/metabolismo , Temperatura Alta , Cinética , Consumo de Oxigênio , Termodinâmica
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