RESUMO
Toxoplasma gondii (T. gondii) is a zoonotic infection that may be transmitted to human beings either by consumption of raw or uncooked meat or by ingesting oocysts. Toxoplasma organisms can cross blood placenta barrier and may result in congenital toxoplasmosis. About 80% of immunocompetent individuals do not show any clinical manifestations and are silent carriers of this disease. Pregnant women especially in highly prevalent areas are recommended to be screened for this disease in order to prevent the potential vertical transmission. To our knowledge no such study has been conducted in this region of Saudi Arabia. This study attempted to carry out two objectives: first, to find out the seroprevalence of T. gondii infection in pregnant women attending prenatal care services in our hospital; second, to find out risk factors associated with T. gondii seroprevalence in our patients. It was carried out in Teaching Hospital in Al-Kharj over a period of one year. All 306 pregnant women attending antenatal clinic were involved in the study. A pretested selfexplanatory questionnaire was filled out by the patients and their sera were collected to be tested for IgG and/or IgM against T. gondii. The results were then statistically analyzed using SPSS software and p-value was calculated using Pearson Chi Square test. Out of the 306 blood samples tested, 99 (32.4%) were seropositive for specific anti T. gondii IgG antibodies and 3(1%) were seropositive for IgM. This show that seroprevalence of T. gondii antibodies was high among pregnant women and the prevalence showed a significant association with age. The study recommends conducting educational programs to raise awareness among women about risk factors and precautions to be taken.
Assuntos
Complicações Parasitárias na Gravidez/epidemiologia , Toxoplasmose/epidemiologia , Adolescente , Adulto , Anticorpos Antiprotozoários/sangue , Feminino , Hospitais de Ensino , Humanos , Imunoglobulina G/sangue , Imunoglobulina M/sangue , Pessoa de Meia-Idade , Gravidez , Cuidado Pré-Natal , Prevalência , Arábia Saudita , Estudos Soroepidemiológicos , Toxoplasma , Adulto JovemRESUMO
Intestinal parasitic infections (IPIs) are a major cause of morbidity worldwide and have been described as an important public health concern. The present study aimed to determine the prevalence and identification of risk factors associated with IPIs among 3-15 years old school age children residing in Mandi Bahauddin, Pakistan from 2011- 2013. A cross sectional school-based study was conducted using a structured pre-tested questionnaire. Anthropometric tools and stool tests were used to obtain epidemiological and disease data. The direct wet mount preperation in saline/iodine/haematoxylin stain and Kato-Katz methods were used for stool examination. Data were analysed using appropriate descriptive, univariate and multivariable logistic regression methods. Of the 1,434 children studied (mean age of 8.6±3.6 years) the overall prevalence rate for intestinal parasitic infections was found to be 33.3%. Children infected with single parasite accounted for 27.6% and 5.7% were detected with poly-parasitism. The study showed that helminths (21.4%) were more prevalent than protozoans (17.9%). Ascaris lumbricoides (17.5%), Giardia lamblia (9.8%), Entamoeba histolytica (8.2%), Hymenolepis nana (2.0%), Trichuris trichiura (1.3%) and Taenia saginata (0.7%) were identified in children living in irrigated areas. The multiple logistic regression model indicated that age of the child, gender, family size, source of drinking water, type of milk used, house condition, feeding habit, personal hygiene and socioeconomic status were significantly (p<0.05) associated with the IPIs. Intestinal parasites were prevalent in varying magnitude among the schoolchildren located in irrigated areas. We conclude that there is a need for mass scale campaigns to create awareness regarding health and hygiene in children, and the need for development of effective poverty control programmes because deworming alone is not adequate to control parasitic infections.
RESUMO
We illustrate a method that uses bovine serum albumin (BSA) to control the receptor-accessible part of rebaudioside A (Reb A). The critical micelle concentration (CMC) of Reb A was found to be 4.5 mM and 5 mM at pH 3 and 6.7 respectively. NMR studies show that below its CMC, Reb A binds weakly to BSA to generate a Reb A-protein complex ("RPC"), which is only modestly stable under varying conditions of pH (3.0-6.7) and temperature (4-40°C) with its binding affinities determined to be in the range of 5-280 mM. Furthermore, saturation transfer difference (STD) NMR experiments confirm that the RPC has fast exchange of the bitterness-instigating diterpene of Reb A into the binding sites of BSA. Our method can be used to alter the strength of Reb A-receptor interaction, as a result of binding of Reb A to BSA, which may ultimately lead to moderation of its taste.
Assuntos
Diterpenos do Tipo Caurano/química , Aditivos Alimentares/química , Soroalbumina Bovina/química , Edulcorantes/química , Percepção Gustatória , Paladar , Sítios de Ligação , Espectroscopia de Ressonância Magnética/métodos , Modelos Teóricos , Ligação Proteica , TemperaturaRESUMO
Artemisia plant genus, natural inhabitant of northern Punjab Pakistan, is well known for its anthelmintic properties; many Artemisia species have not been so far scientifically proved. The aim of this study was to assess in vitro anthelmintic activity of Artemisia indica and Artemisia roxburghiana against mixed infection of gastrointestinal nematodes in small ruminants. This study is first scientifically proven study on anthelmintic activity of A. indica and A. roxburghiana. Five different concentrations (50, 25, 12.5, 6.25 and 3.75 mg/mL) accompanied by negative control (PBS) and positive control (albendazole, 10%) were used to carry out the egg hatch inhibition assay, larval mortality assay and adult worm mortality assay. The Baermann technique was used first time in larval mortality assay and proved to be effective. The results revealed that methanolic extracts of both A. indica and A. roxburghiana, showed maximum anthelmintic activity at concentration of 50 mg/ml by egg hatch inhibition (85±21.2; 80±28.3), larvae mortality (18±2.8; 17±4.2) and adult worm mortality (8.5±2.1; 8±2.8) assays. However, at concentration of 50 mg/ml both plant extracts in comparison to albendazole showed statistically insignificant (p≤0.05) results. The A. indica showed higher anthelmintic activity at all concentrations as compared to A. roburghiana. It has been concluded both plants exhibit anthelmintic activity and further evaluation of these plants should be carried out to purify the active ingredients for anthelmintic activity. Moreover, the decoctions of these plants could be used to GINs after confirming anthelmintic properties through in vivo.
Assuntos
Anti-Helmínticos/farmacologia , Artemisia/química , Nematoides/efeitos dos fármacos , Extratos Vegetais/farmacologia , Animais , Anti-Helmínticos/isolamento & purificação , Bioensaio , Paquistão , Testes de Sensibilidade Parasitária , Extratos Vegetais/isolamento & purificação , Análise de SobrevidaRESUMO
We investigated a possible modulation of growth hormone (GH) secretion by testosterone by measuring the growth hormone releasing hormone (GHRH)-stimulated and N-methyl-d,l-aspartic acid (NMA)-induced GH secretion in adult rhesus monkeys. Intact, orchidectomized and testosterone-substituted (testosterone enanthate 125 mg/week, i.m. for 5 weeks) orchidectomized monkeys (n=5) were used in the study. GHRH (25 microg/kg body weight) or NMA (15 mg/kg body weight) was infused through a Teflon cannula implanted in the saphenous vein. Sequential blood samples were collected 30-60 min before and 60 min after the injection of the neurohormone or the drug at 10-20-min intervals. All bleedings were carried out under ketamine hydrochloride anaesthesia (initial dose 5 mg/kg body weight i.m., followed by 2.5 mg/kg at 30-min intervals). The plasma concentrations of GH, testosterone and oestradiol (E(2)) were determined by using specific assay systems. Administration of GHRH elicited a significant increase in GH secretion in all three groups of animals. There was no significant difference in the responsiveness of pituitary somatotrophs to exogenous GHRH challenges between intact and orchidectomized monkeys and testosterone replacement in orchidectomized animals did not significantly alter the GHRH-induced GH response. The responsiveness of hypothalamic GHRH neurones apparently did undergo a qualitative change after orchidectomy, as GH response to NMA was less in orchidectomized animals than in intact monkeys. The responsiveness of GHRH neurones to exogenous NMA was restored and even potentiated when orchidectomized monkeys were treated with testosterone. Taken together, these findings suggest that testosterone does not affect the sensitivity of the pituitary somatotrophs to GHRH but stimulates the secretion of GH by modulation of the NMDA drive to GHRH neurones.
Assuntos
Hormônio Liberador de Hormônio do Crescimento/farmacologia , Hormônio do Crescimento/metabolismo , Hipotálamo/efeitos dos fármacos , N-Metilaspartato/farmacologia , Adeno-Hipófise/metabolismo , Testosterona/farmacologia , Análise de Variância , Animais , Estradiol/sangue , Hormônio do Crescimento/sangue , Hormônio Liberador de Hormônio do Crescimento/metabolismo , Hipotálamo/metabolismo , Macaca mulatta , Masculino , Orquiectomia , Estimulação Química , Testosterona/sangueRESUMO
Using the UBC test, the specificity, sensitivity and prognostic information were evaluated in patients with recently diagnosed transitional cell carcinoma (TCC) and in a control group consisting of apparently healthy individuals and individuals with benign disorders. Frozen urine samples from the 485 individuals in the control group and 100 newly diagnosed TCC patients were analyzed with the UBC test, specific for epitopes on cytokeratin fragments released from the urothelial cells. All the samples were analyzed and corrected for creatinine. No significant concentration difference was found between males and females (p=0.65) and there was no age dependent relation. The median concentration for the entire control group was estimated at 3.7 microg/g and the 95th percentile was calculated at 53.0 microg/g. The apparently healthy individuals in the control group had a median value of 3.4 microg/g with a 95th percentile of 24.3 microg/g. An increased frequency of elevated UBC concentrations was found in some benign disorders e.g., anemia, thyroid disorders, diabetes mellitus, hyperlipemia, urosepsis and cystitis. Patients with superficial tumors exhibited a 66% sensitivity (at 95% specificity), and the UBC concentrations did not differ statistically (p=0.16) from those patients with muscle invasive lesions with a 52% sensitivity. When the UBC concentrations were related to histopathological grade, a significant concentration difference (p<0.004) was found between low grade tumors (sensitivity 41%) and high grade tumors (sensitivity 72%). Survival analysis showed that patient with muscle invasive tumors, high-grade tumors and high UBC concentrations have a significantly reduced survival (five-year survival was estimated to 30%, 35% and 30% respectively) compared to patients with superficial tumors, low-grade tumors or low UBC concentrations (five-year survival, 60%, 85% and 75% respectively). The UBC test showed good accuracy and repeatability. Clinically the test could assist in tumor grading and the detection of recurrent disease, which in turn could assist in treatment selection for the individual patient and possibly improve prognosis.
Assuntos
Carcinoma de Células de Transição/urina , Ensaio de Imunoadsorção Enzimática , Queratinas/urina , Kit de Reagentes para Diagnóstico , Neoplasias da Bexiga Urinária/urina , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anemia/urina , Carcinoma de Células de Transição/patologia , Criança , Pré-Escolar , Cistite/urina , Diabetes Mellitus/urina , Feminino , Humanos , Hiperlipidemias/urina , Masculino , Estadiamento de Neoplasias , Fragmentos de Peptídeos/urina , Valores de Referência , Sensibilidade e Especificidade , Análise de Sobrevida , Doenças da Glândula Tireoide/urina , Neoplasias da Bexiga Urinária/patologiaRESUMO
The present study attempts to examine the role of N-methyl-D-aspartate (NMDA) receptor in the central regulation of growth hormone (GH) secretion during specific stages of pubertal development of the male rhesus monkey (Macaca mulatta). Infantile (n=4), prepubertal (n=5), peripubertal (n=5) and adult (n=5) intact male rhesus monkeys were given an agonist of NMDA receptor, N-methyl-D,L-aspartate (NMA) (15 mg/kg BW) through a teflon cannula implanted in the saphenous vein. Blood samples were collected 20-60 min before and 40-80 min after the injection of the drug at 10-20 min intervals. NMA was dissolved in normal saline immediately before use and passed through a 0.22 microm filter at the time of injection. All bleedings were carried out under ketamine hydrochloride anesthesia (initial dose 5 mg/kg BW, im followed by 2.5 mg/kg at 30 min intervals). The plasma levels of GH and testosterone (T) were determined by using specific assay systems. The hypothalamic-somatotrope activity under basal conditions was studied by averaging all the GH concentrations obtained before NMA injection, whereas the sensitivity of NMDA receptor to NMA stimulation was determined by comparing basal GH levels immediately before NMA injection at 0 min and GH concentrations obtained 10 min after the injection. The mean basal plasma concentrations of GH in the four groups of animals showed marked age-related differences. The levels of GH were found to be higher in infantile and peripubertal monkeys as compared to those of prepubertal and adult animals. A single iv injection of NMA produced differential effects on GH secretion during specific stages of postnatal development depending upon the level of GH secretion under basal conditions. Whereas NMA had no demonstrable effect on GH secretion in infantile and peripubertal animals in which the basal GH levels were high, it produced pronounced effects on GH secretion in prepubertal and adult monkeys wherein baseline GH concentrations were low. In conclusion, the present study suggests that the glutamatergic component of the control system that governs GH secretion by utilizing NMDA receptor may participate in regulation of age-related changes in the secretion of GH in the male rhesus monkey.
Assuntos
Hormônio do Crescimento/metabolismo , Crescimento/fisiologia , Receptores de N-Metil-D-Aspartato/agonistas , Animais , Peso Corporal/fisiologia , Agonistas de Aminoácidos Excitatórios/farmacologia , Hormônio do Crescimento/sangue , Macaca mulatta , Masculino , N-Metilaspartato/farmacologia , Tamanho do Órgão/fisiologia , Receptores de N-Metil-D-Aspartato/fisiologia , Maturidade Sexual/fisiologia , Testículo/anatomia & histologia , Testosterona/sangueRESUMO
N-methyl-D,L-aspartic acid (NMA), an agonist of the neurotransmitter glutamate has been shown to acutely stimulate the release of prolactin (PRL) in intact rats and monkeys. To further investigate the role of neuroexcitatory amino acids in PRL secretion, the effects of NMA administration were examined on PRL release in long term orchidectomized adult rhesus monkeys, in both the absence and presence of testosterone. Intact and long term castrated adult male monkeys weighing between 8-13 kg, were implanted with a catheter via the saphenous vein for blood withdrawal and drug infusion. Blood samples were collected at 10 min intervals for 50 min before and 70 min after administration of the drug or vehicle. Plasma PRL concentrations were estimated using radioimmunoassay. Whereas a single iv injection of NMA (15 mg/kg BW) induced a prompt discharge of PRL in intact monkeys, an identical dose had surprisingly no effect on PRL secretion in orchidectomized animals. On the other hand, plasma PRL increases in response to a challenge dose of thyrotropin releasing hormone (TRH; 6 micrograms/kg BW, iv) were similar in magnitude in the two groups of monkeys. Testosterone replacement in orchidectomized animals by parenteral administration of testosterone enanthate (200 mg/wk) reinitiated the PRL responsiveness to acute NMA stimulation. These results indicate that N-methyl-D-aspartic acid (NMDA) dependent drive to PRL release in the adult male rhesus monkey may be overtly influenced by the sex steroid milieu.
Assuntos
N-Metilaspartato/farmacologia , Prolactina/sangue , Testosterona/farmacologia , Animais , Macaca mulatta , Masculino , Orquiectomia , Radioimunoensaio , Hormônio Liberador de Tireotropina/farmacologiaRESUMO
TMB-8 [8-(diethylamino)-octyl-3,4,5-trimethoxybenzoate] is known to inhibit calcium ion dependent processes in several tissues by stabilizing some intracellular stores of membrane-bound calcium. TMB-8 was used to study the excitation-contraction (E-C) coupling process in frog's skeletal muscle. TMB-8 (5 X 10(-5) - 10(-4) M) blocked electrically evoked twitches but not high K+ (123 mM)- or caffeine (2.36 mM)-induced contractures in isolated, curarized toe muscles. TMB-8 (10(-4) M) produced a small decrease (16%) in the action potential of frog's sartorius muscle fibres. However, reducing extracellular Na+ to 44.7 mM produced a similar reduction (17%) in action potential amplitude but did not suppress the twitch; i.e. it produced only a small increase (about 10%) in twitch amplitude. It is known that potassium contractures are produced by extracellular Ca++ ions which enter through calcium channels in the t-tubules and that caffeine produces contractures by sensitizing the sarcoplasmic reticulum to Ca++-induced Ca++ release. The present results suggest that TMB-8 blocks twitches by preventing the release of Ca++ ions bound to the intracellular surface of the t-tubular membrane which is often called the store of 'trigger-calcium' ions.
Assuntos
Cafeína/farmacologia , Ácido Gálico/análogos & derivados , Contração Muscular/efeitos dos fármacos , Músculos/efeitos dos fármacos , Potássio/farmacologia , Potenciais de Ação/efeitos dos fármacos , Animais , Cálcio/metabolismo , Ácido Gálico/farmacologia , Técnicas In Vitro , Rana pipiensRESUMO
The excitatory amino acids (EAAs), glutamate and aspartate, acting predominantly on N-methyl-D-aspartate (NMDA) receptor, have been shown to be involved in the central regulation of the secretion of several anterior pituitary hormones including prolactin (PRL), whereas ketamine hydrochloride (KH), a widely used anesthetic, has been reported to antagonize a variety of NMDA receptor mediated actions of these EAAs. In the present study, the effect of KH on basal PRL levels as well as on N-methyl-D,L-aspartate (NMA), an agonist of NMDA receptor, induced plasma PRL secretion was investigated in the adult male rhesus monkey. The values were compared to those obtained from the same animals restrained in primate chairs. The plasma PRL concentrations were higher in animals receiving KH administered either intramuscularly (2.5 mg/kg BW at 30 min intervals) or intravenously (10 mg/kg BW) as compared to those observed in the unanesthetized chair-restrained monkeys. NMA induced an unequivocal increase in plasma PRL concentrations in both conscious chair-restrained and KH anesthetized monkeys, but the response was greater in anesthetized animals than the conscious monkeys. The present findings suggest that KH has stimulatory effects on both basal and NMA induced plasma PRL secretion.
Assuntos
Antagonistas de Aminoácidos Excitatórios/farmacologia , Ketamina/farmacologia , N-Metilaspartato/farmacologia , Prolactina/sangue , Anestésicos Dissociativos/farmacologia , Animais , Esquema de Medicação , Interações Medicamentosas , Injeções Intramusculares , Macaca mulatta , Masculino , Prolactina/metabolismo , Receptores de N-Metil-D-Aspartato/agonistas , Receptores de N-Metil-D-Aspartato/antagonistas & inibidores , Estimulação QuímicaRESUMO
In the present study, the pituitary growth hormone (GH) response to graded doses of GH-releasing hormone (GHRH) was determined in intact (n = 3) and chronically orchidectomized (n = 3) adult rhesus monkeys (Mucaca mulatta). GHRH in doses of 0, 6.25, 12.5 and 25 microg/kg BW was infused through a teflon cannula implanted in the saphenous vein. Blood samples were collected 60 min before and 90 min after the injection of the neurohormone at 15 min intervals. All bleedings were carried out under ketamine hydrochloride anesthesia. The plasma levels of GH were determined by using AutoDELFIA time-resolved flouroimmunoassay, whereas plasma levels of testosterone and estradiol were determined using specific radioimmunoassay systems. The GH responses to GHRH were not significantly different between intact and chronically orchidectomized monkeys at any of the dose levels tested (p > 0.05). The administration of GHRH resulted in a significant (p < 0.05) stimulation of GH secretion at all the doses tested and in both the groups studied. In both intact and orchidectomized animals, the greatest response was observed at 6.25 microg/kg and no further increase was noted with the higher doses of GHRH. In conclusion, the present study suggests that chronic orchidectomy does not influence the sensitivity of the pituitary somatotropes to GHRH stimulation implying that the responsiveness of the pituitary somatotropes to GHRH is independent of testicular steroid modulation.
Assuntos
Hormônio Liberador de Hormônio do Crescimento/farmacologia , Hormônio do Crescimento/sangue , Macaca mulatta/metabolismo , Orquiectomia/veterinária , Adeno-Hipófise/efeitos dos fármacos , Análise de Variância , Animais , Relação Dose-Resposta a Droga , Estradiol/sangue , Fluorimunoensaio , Hormônio do Crescimento/metabolismo , Masculino , Adeno-Hipófise/metabolismo , Radioimunoensaio , Testosterona/sangue , Fatores de TempoRESUMO
Since the literature has a paucity of documented lesions of the vestibular hair cells and neurons in Menière's disease, the cause of canal paresis remains unexplained. A clinicopathological correlation was sought and demonstrated between ampullary distortion of lateral canal and reduced caloric response. The findings in this investigation make a strong case for ampullary distortion disrupting the tenuous but vital cupulary attachment resulting in canal paresis. This concept is attractive because it explains an important clinical event in Menière's disease on the basis of the only consistent histopathological finding, namely, membrane distension.
Assuntos
Meato Acústico Externo , Doença de Meniere/complicações , Paresia/etiologia , Adolescente , Adulto , Idoso , Testes Calóricos , Meato Acústico Externo/patologia , Edema/complicações , Endolinfa , Feminino , Humanos , Masculino , Doença de Meniere/patologia , Doença de Meniere/fisiopatologia , Pessoa de Meia-Idade , Estudos Prospectivos , Estudos RetrospectivosRESUMO
OBJECTIVE/HYPOTHESIS: Sensorineural hearing loss is a disturbing complication of microvascular decompression (MVD) for trigeminal neuralgia with an incidence of 1% to 23.8%. Cerebellar retraction with increasing I-V interpeak latency (IPL) during intraoperative brainstem auditory evoked potentials (BAEP) has been identified as the chief cause of acoustic injury. This study was designed to eliminate cerebellar retraction by a modification of the standard suboccipital craniectomy. STUDY DESIGN: Nine consecutive patients undergoing surgery for trigeminal neuralgia were prospectively selected for this study between 1994 and 1995. METHODS: Preoperative and postoperative audiograms were obtained. Preoperative and intraoperative BAEPs were performed. The surgical modification describes initiating a partial mastoidectomy to enhance early recognition and delineation of the sigmoid and transverse sinuses crucial to maximizing the lateral extent of the craniectomy. The additional exposure gained by this technique allows for improved visualization of the brainstem without cerebellar retraction. RESULTS: All patients were relieved of neuralgic pain. Postoperative IPL values were not significantly different from preoperative values (4.9+/-0.6 vs. 4.7+/-0.3 ms). Maintaining IPL of less than 1.5 ms is considered critical for preventing injury to the auditory nerve. In this study the average increase in postoperative IPL was 0.25 ms for the ipsilateral ear and 0.1 ms for the contralateral ear. CONCLUSIONS: The authors offer a surgical modification of the standard suboccipital craniectomy and furnish intraoperative neurophysiologic data to demonstrate how cerebellar compression can be eliminated and hearing preserved in MVD for trigeminal neuralgia.
Assuntos
Descompressão Cirúrgica/métodos , Audição/fisiologia , Neuralgia do Trigêmeo/cirurgia , Adulto , Idoso , Audiometria de Tons Puros , Condução Óssea/fisiologia , Potenciais Evocados Auditivos do Tronco Encefálico/fisiologia , Feminino , Perda Auditiva Neurossensorial/prevenção & controle , Humanos , Masculino , Processo Mastoide/cirurgia , Microcirculação/fisiologia , Pessoa de Meia-Idade , Monitorização Intraoperatória , Cuidados Pós-Operatórios , Cuidados Pré-Operatórios , Estudos Prospectivos , Teste do Limiar de Recepção da Fala , Neuralgia do Trigêmeo/diagnósticoRESUMO
The vestibular aqueduct (VA) and endolymphatic sac were examined topographically in 29 human ears with idiopathic endolymphatic hydrops. When compared with 34 control ears, there was found to be a slight but statistically significant reduction in the width (P less than 0.005) and length (P less than 0.05) of the vestibular aqueduct. A small hypoplastic endolymphatic sac was found in three of the ears with hydrops but was also present in one control ear. It would appear that a marked reduction in sac size is not a consistent feature in ears with endolymphatic hydrops.
Assuntos
Doença de Meniere/patologia , Aqueduto Vestibular/patologia , Vestíbulo do Labirinto/patologia , Saco Endolinfático/patologia , Humanos , Doença de Meniere/etiologiaRESUMO
Five temporal bones exhibiting transverse fractures were studied with a view to determining whether such fractures could lead to symptomatic endolymphatic hydrops. Four out of the five temporal bones showed the fracture line traversing the vestibular aqueduct. Two of these four showed complete obstruction of the endolymphatic duct. One of these had an intact membranous labyrinth and severe endolymphatic hydrops. The other had ruptures of the membranous labyrinth and no hydrops. Three ears exhibited partial preservation of auditory and vestibular hair cells and neurons. These findings are consistent with the concept that a transverse fracture may produce endolymphatic hydrops by obstructing the vestibular aqueduct while preserving enough audiovestibular epithelium and neurons to present as symptomatic Menière's disease.
Assuntos
Edema/etiologia , Fraturas Ósseas/complicações , Osso Temporal/lesões , Aqueduto Vestibular/lesões , Vestíbulo do Labirinto/lesões , Adulto , Idoso , Endolinfa , Ducto Endolinfático/patologia , Perda Auditiva Neurossensorial/etiologia , Humanos , Masculino , Doença de Meniere/etiologia , Pessoa de Meia-Idade , Vestíbulo do Labirinto/patologiaRESUMO
The requirements of barrier properties of packaging materials against environmental factors vary with food products. The chemical, physical, and biological mechanisms of food deterioration due to environmental factors, vital properties required in packaging materials, and developments in progress and future trends to maintain the required standard of food quality have been critically reviewed. Theoretical and experimental results for a variety of food products in relation to the properties of the packaging materials are discussed. Methods of prediction of food stability and their industrial applications are also emphasized by specific examples.
Assuntos
Manipulação de Alimentos/normas , Conservação de Alimentos/normas , Polímeros , Celofane , Comércio , Contaminação de Alimentos/prevenção & controle , Manipulação de Alimentos/economia , Alimentos Congelados/normas , Polietilenos , Cloreto de Polivinila/análogos & derivados , Polivinil , Meios de Transporte , VácuoRESUMO
Physico-chemical properties of retentates obtained from selective concentration of skim milk up to 8 times its original weight using a microfiltration system were studied. The effects of process variables, namely concentration (8.6 to 27 wt.%), temperature (20 to 50 degrees C) and pH (6.0, 6.3, and 6.5) on density (rho), apparent viscosity (mu(a)), consistency coefficient (K), flow behavior index (n), and activation energy (Ea) of the retentates were examined. Depending on pH, retentates showed significant increase in apparent viscosity, deviated from classical Newtonian behavior and exhibited shear-thinning between 11 to 17% solids concentration. No yield stress was detected in the range of concentration studied. The power law parameters (n and K) followed a similar trend. An Arrhenius-type equation described well the effect of temperature on apparent viscosity. Although activation energy increased 120 to 130% for a threefold increase in solids concentration, it was not significantly different from that of other types of concentrated milk at approximately the same concentration. Increasing solids were responsible for change in flow properties with concentration, while the effect of pH was attributed to differential protein (primarily casein) retention and the change in solvation properties and voluminosity of casein micelles. Models relating concentration, temperature, and pH to retentate apparent viscosity and consistency coefficient were identified. Skim milk microfiltration with in-process pH adjustment produces retentates depleted in whey proteins and calcium with significantly altered properties.