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Biomedical subjects

B Robinson

Publications and source records attributed to B Robinson.

At least 55 records · Page 3Linked to original sources
PubMed1999

In rats, odor-induced Fos in the olfactory pathways depends on the phase of the circadian clock.

We used immunostaining for Fos to study the effect of circadian clock phase on odor-induced neuronal activation in the olfactory system in rats. Brief presentation of cedar odor to rats housed in constant darkness stimulated Fos expression in the main olfactory bulb, anterior olfactory nucleus, piriform cortex, and several other odor-responsive structures, both in the subjective day and subjective night phases of the cycle. Fos expression in response to odor, but not basal expression, was greatly enhanced in the subjective night in all structures examined. These findings are consistent with the idea that odor-induced neuronal activation in the olfactory pathways is modulated by the phase of the circadian clock.

Animals↗
PubMed1999

Olfactory stimulation enhances light-induced phase shifts in free-running activity rhythms and Fos expression in the suprachiasmatic nucleus.

There is evidence to suggest that the olfactory and circadian systems are linked, functionally, and that olfactory stimuli can modulate circadian rhythms in mammals. Furthermore, olfactory bulb removal can alter free-running rhythms in animals housed in constant darkness and can attenuate the effect of social stimuli on photic entrainment of circadian rhythms. The mechanisms through which olfactory stimuli influence circadian rhythms are not known. One possibility is that olfactory stimuli influence circadian rhythms by modulating the activity of the circadian clock located in the hypothalamic suprachiasmatic nucleus. To study this, we assessed the effect of olfactory stimulation on free-running rhythms and on photic resetting of the circadian clock in rats using phase shifts in wheel-running rhythms and expression of the transcription factor Fos in the suprachiasmatic nucleus. We found that brief exposure to an olfactory stimulus, cedar wood essence, in the subjective day or subjective night had no effect on either free-running rhythms or Fos expression in the suprachiasmatic nucleus, but that when presented in combination with light, the odor dramatically enhanced light-induced phase shifts and Fos expression in the suprachiasmatic nucleus. Olfactory stimulation alone induced Fos expression in several structures that innervate the suprachiasmatic nucleus, pointing to ways by which stimulus information transmitted in the olfactory pathways could gain access to the suprachiasmatic nucleus to modulate photic resetting. These findings, showing that clock resetting by light can be facilitated by olfactory stimulation, point to a mechanism by which olfactory cues can modulate entrainment of circadian rhythms.

Animals↗
PubMed1999

Incidence of pancreatitis in patients undergoing sphincter of Oddi manometry (SOM).

OBJECTIVE: Sphincter of Oddi manometry (SOM) is a useful diagnostic procedure when evaluating patients with unexplained biliary pain or idiopathic recurrent pancreatitis. Acute pancreatitis is a recognized complication of SOM whose pathogenesis appears to be multifactoral. We conducted this study to determine the incidence of pancreatitis in patients after SOM and to identify any variables that may lead to an increased incidence of pancreatitis. METHODS: A retrospective review of 100 consecutive patients who underwent SOM between 1992 and 1996 at two university-affiliated hospitals was done. SOM was performed using a triple lumen catheter with each lumen perfused at a rate of 0.25 cc/min using an Arndorfer pneumohydraulic capillary perfusion system. The following data were recorded: age, gender, clinical type of sphincter of Oddi dysfunction, length of procedure, doses of medications used, duct cannulated, sphincter of Oddi pressure, whether endoscopic retrograde cholangiopancreatography (ERCP) with or without sphincterotomy was performed, and the number of patients developing pancreatitis. Statistical analysis was performed using a T test, chi2, and multiple regression analysis. RESULTS: The overall incidence of pancreatitis was 17%. Six patients with type II SO dysfunction and 11 patients with type III SO dysfunction developed pancreatitis. The incidence of pancreatitis was significantly lower in those patients who only had SOM, compared with those patients who had SOM and ERCP (9.3% vs 26.1%, p < 0.026). There was no significant correlation between age, gender, duration of procedure, dose of midazolam used, sphincter of Oddi pressure, or type of SO dysfunction with the development of SOM-induced pancreatitis. Multiple regression analysis showed that sphincterotomy added no additional risk, beyond that associated with ERCP, for the development of pancreatitis. CONCLUSIONS: The results of this study indicate that the incidence of pancreatitis was highest when SOM was followed by ERCP. A potential method of decreasing the incidence of pancreatitis after SOM is performing ERCP with or without sphincterotomy at another session, separated from the SOM by at least 24 h. Before this can be definitely recommended, the results of this study must be validated by others or by a prospective study.

Acute Disease↗
PubMed1999

Measurement of the validity of a preschool vision screening program.

OBJECTIVES: The validity (sensitivity and specificity) of a preschool vision screening program was measured over a 3-year period to determine how well strabismus and significant refractive errors could be detected. METHODS: Public health nurses were trained to administer tests of visual acuity, stereoacuity, and ocular alignment. Failure on any test, visual acuity of 6/9 or less, stereoacuity of less than 100 seconds of arc, or an apparent misalignment of the eyes resulted in referral to an eye care practitioner. An age-matched control was also referred. Analysis of practitioner reports used predefined study-based criteria for ocular abnormalities. RESULTS: More than 1100 children were screened each year. The annually calculated prevalence of vision problems ranged between 10.5% and 13.8%. The estimated sensitivity varied from 60.4% to 70.9% (specificity, 69.6% to 79.9%). The yield indicated that a very high percentage of children with vision problems were identified for the first time. CONCLUSIONS: The validity of this screening is comparable to that of other school screenings. The limitations are predictable. Consideration should be given to replacing visual acuity tests with a rapid, objective measure of refractive error and ocular alignment.

Age Factors↗
PubMed1999

Influence of carbohydrate source and buffer on rumen fermentation characteristics, milk yield, and milk composition in early-lactation Holstein cows.

The effects of concentrate to forage ratio and sodium bicarbonate (buffer) supplementation on intake, ruminal fermentation characteristics, digestibility coefficients, milk yield, and milk composition were examined in 4 cannulated Holstein cows (100 +/- 20 d in milk). A 4 x 4 Latin square design with 2 x 2 factorial arrangement of treatments was implemented for 3-wk experimental periods. The 4 treatments were a 50:50 concentrate to forage ratio with 1.2% of dry matter (DM) and without added buffer and a 75:25 concentrate to forage ratio with (1.2% of DM) and without (0% of DM) buffer. The forage component of the ration was a 50:50 mixture of alfalfa and barley and triticale silage, and diets were fed ad libitum as a total mixed ration. Although feed intake was not influenced by treatments, substantial treatment differences were observed for milk yield and milk composition. Cows fed high-concentrate diet had lower ruminal pH, ruminal acetate, and butyrate concentrations, whereas propionate concentrations were significantly elevated. The addition of buffer, at both levels of concentrate inclusion, resulted in elevated total volatile fatty acids and acetate concentrations. We concluded that altering the forage concentrate ratio in the diet of lactation cows influenced milk yield and milk composition, but the addition of buffer to the diet prevented the elevation in trans-C18:1 fatty acids in milk fat, and related milk fat depression, associated with feeding high-concentrate diets.

Acetates↗
PubMed1998

Genetic and biochemical screening for endocrine disease: III. Costs and logistics.

The cost of screening tests in endocrine disease can be determined in a number of ways, including the charge or billed cost, the production cost, or most appropriately the cost to achieve the intended aim of the test (cost-effectiveness). Cost-effectiveness analysis allows clinicians to determine whether an added benefit of a test comes at an acceptable cost. For example, analysis of the cost-effectiveness of routine thyroid function tests prior to surgery in elderly patients with nodular thyroid disease shows that the cost per life saved is only US $405, making the tests clearly cost-effective. Cost-effectiveness does not always equate with affordability, however, especially in developing countries. Thyroid function testing prior to surgery represents only 0.8% of the average household income in Australia and is therefore both cost-effective and affordable, whereas in Sri Lanka the same screening test represents up to 50% of the average monthly income. A survey of membership of the International Association of Endocrine Surgeons worldwide showed that molecular genetic screening for endocrine disease is readily available in 67% of institutions, with all of those having facilities for the rearrangement during transfection (RET) proto-oncogene testing, and lesser numbers having access to the Menin gene, the von Hippel-Lindau syndrome (VHL) gene, or linkage analysis for familial pheochromocytoma. The median cost of screening for the RET proto-oncogene was $290 (range $100-3000). Cost-effectiveness analysis of molecular genetic screening for MEN-II syndrome demonstrates that the cost per life saved is only $5175. This compares favorably with reliance on screening based on annual pentagastrin testing, where the cost per life saved is as high as $76,315. Molecular genetic screening for endocrine disease (e.g., the MEN-II syndrome) is not only cost-effective but the therapy required (total thyroidectomy) is both acceptable and well tolerated.

Cost-Benefit Analysis↗
PubMed1998

A role for serotonin in the circadian system revealed by the distribution of serotonin transporter and light-induced Fos immunoreactivity in the suprachiasmatic nucleus and intergeniculate leaflet.

Components of the circadian system, the suprachiasmatic nucleus and the intergeniculate leaflet receive serotonin input from the raphe nuclei. Manipulations of serotonin neurotransmission disrupt cellular, electrophysiological, and behavioural responses of the circadian system to light, suggesting that serotonin plays a modulatory role in photic regulation of circadian rhythms. To study the relation between serotonin afferents and light-activated cells in the suprachiasmatic nucleus and intergeniculate leaflet, we used immunostaining for the serotonin transporter and for the transcription factor, Fos. Serotonin transporter, a plasma membrane protein located on serotonin neurons, regulates the amount of serotonin available for neurotransmission by re-accumulating released serotonin into presynaptic neurons; expression of Fos in the suprachiasmatic nucleus identifies light-activated cells involved in photic resetting of circadian clock phase. In the suprachiasmatic nucleus, immunostaining for serotonin transporter revealed a dense plexus of fibres concentrated primarily in the ventrolateral region. In the intergeniculate leaflet, serotonin transporter immunostaining identified vertically-oriented columns of fibres. Serotonin transporter immunostaining was abolished by pretreatment with the serotonin neurotoxin, 5,7-dihydroxytryptamine. Exposure to light for 30 min during the dark phase of the light cycle induced Fos expression in the ventrolateral suprachiasmatic nucleus and intergeniculate leaflet regions. In both structures the Fos-expressing cells were encircled by serotonin transporter-immunoreactive fibres often in close apposition to these cells. These results support the idea that serotonin activity plays a modulatory role in processing of photic information within the circadian system.

Animals↗
PubMed1998

Thymic carcinoids in multiple endocrine neoplasia type 1.

OBJECTIVE: To study the clinical, pathologic, and genetic features of thymic carcinoids in the setting of multiple endocrine neoplasia type 1 (MEN1) and to study means for detection and prevention of this tumor in patients with MEN1. SUMMARY BACKGROUND DATA: Thymic carcinoid is a rare malignancy, with approximately 150 cases reported to date. It may be associated with MEN1 and carries a poor prognosis, with no effective treatment. Its underlying etiology is unknown. METHODS: Ten patients with MEN1 from eight families with anterior mediastinal tumors were included in a case series study at tertiary referring hospitals. Clinicopathologic studies were done on these patients, with a review of the literature. Mutation analysis was performed on the MEN1 gene in families with clusterings of the tumor to look for genotype-phenotype correlation. Loss of heterozygosity was studied in seven cases to look for genetic abnormalities. RESULTS: Histologic studies of all tumors were consistent with the diagnosis of thymic carcinoid. Clustering of this tumor was found in some of the families-three pairs of brothers and three families with first- or second-degree relatives who had thymic carcinoid. All patients described here were men, with a mean age at detection of 44 years (range 31 to 66). Most of the patients had chest pain or were asymptomatic; none had Cushing's or carcinoid syndrome. All tumors were detected by computed tomography (CT) or magnetic resonance imaging (MRI) of the chest. The results of octreoscans performed in three patients were all positive. Histopathologic studies were consistent with the diagnosis of thymic carcinoid and did not stain for ACTH. Mutation analysis of the families with clustering revealed mutations in different exons/introns of the MEN1 gene. Loss of heterozygosity (LOH) studies of seven tumors did not show LOH in the MEN1 region, but two tumors showed LOH in the 1p region. CONCLUSIONS: MEN1-related thymic carcinoids constitute approximately 25% of all cases of thymic carcinoids. In patients with MEN1, this is an insidious tumor not associated with Cushing's or carcinoid syndrome. Local invasion, recurrence, and distant metastasis are common, with no known effective treatment. We propose that CT or MRI of the chest, as well as octreoscanning, should be considered as part of clinical screening in patients with MEN1. We also propose performing prophylactic thymectomy during subtotal or total parathyroidectomy on patients with MEN1 to reduce the risks of thymic carcinoid and recurrence of hyperparathyroidism. Its male predominance, the absence of LOH in the MEN1 region, clustering in close relatives, and the presence of different MEN1 mutations in these families suggest the involvement of modifying genes in addition to the MEN1 gene. A putative tumor suppressor gene in 1p may be involved.

Adult↗
PubMed1998

Familial isolated hyperparathyroidism maps to the hyperparathyroidism-jaw tumor locus in 1q21-q32 in a subset of families.

Approximately 70 families with familial isolated hyperparathyroidism (FIHP) have been reported. Whether it is a separate entity or a variant of multiple endocrine neoplasia type 1 (MEN1 at 11q13) or hyperparathyroidism-jaw tumor (HPT-JT or HRPT2 at 1q21-32) syndrome is not known. We describe here 3 unreported families with familial primary hyperparathyroidism and evaluate their clinical, pathological, and genetic profiles. Biochemical and radiological screenings for MEN1 were negative for all families. In 2 families with a total of 10 affected cases and 3 female obligate carriers, there is no evidence of jaw or renal lesions despite careful radiological investigations. In both families the disease was linked to the 1q21-q32 region with the maximum logarithm of the odds (lod) scores of 3.10 and 3.43 for markers D1S222 and D1S249 respectively, at recombination fraction of 0. In 1 family 2 types of parathyroid pathology were found: 3 of chief cell type and 1 of oxyphil/oncocytic cell type. Two chief cell tumors and 1 oxyphil tumor were found to have loss of heterozygosity (LOH) involving loss of the wild-type alleles for chromosome 1q markers. In the third family, with 4 affected siblings, a parathyroid carcinoma and 2 cases of polycystic kidney disease were found. The parathyroid carcinoma also showed loss of heterozygosity in the 1q region. In conclusion, we found that the hyperparathyroidism traits in a subset of FIHP families are linked to the 1q21-32 markers in the HRPT2 region. We describe the spectrum of parathyroid disease in 1q-linked families involving 3 different types of pathology and demonstrate for the first time loss of wild-type alleles in these parathyroid tumors. Taken together, the results suggest that some of the FIHP are a variant of HPT-JT and that the gene involved is a tumor suppressor gene.

Adult↗
PubMed1997

Magnetic resonance imaging compared with echocardiography in the evaluation of pulmonary artery abnormalities in children with tetralogy of Fallot following palliative and corrective surgery.

BACKGROUND: Abnormalities of the pulmonary arteries following palliative or corrective surgery for tetralogy of Fallot (TOF) are common. Our purpose was to compare the usefulness of magnetic resonance imaging (MRI) and echocardiography in the post- operative evaluation of the pulmonary arteries in children with TOF. OBJECTIVE: Our hypothesis was that MRI is more sensitive than echocardiography in the detection of branch pulmonary artery abnormalities in children with TOF. MATERIALS AND METHODS: Pulmonary artery MRI and echocardiography were performed in 20 children following palliative and/or corrective surgery for TOF. MRI and echocardiography were compared in their ability to detect abnormalities of the pulmonary arteries. Angiographic or surgical correlation was available in 15 children. A perfusion scan for confirmation of pulmonary artery patency was available in one additional child. RESULTS: Abnormalities of the branch pulmonary arteries identified by MRI included: absence or occlusion (2), focal stenosis (15), hypoplasia (2), aneurysm (1), and non-confluence (1). Echocardiography could not adequately visualize the right and left branch pulmonary arteries in eight and ten children, respectively. Echocardiography missed stenosis in 13 branch pulmonary arteries, patency of hypoplastic pulmonary arteries in two children, non-confluence of the pulmonary arteries in one child, and a left pulmonary artery aneurysm in one child. Abnormalities identified by MRI were confirmed in 16 children by angiography, surgery or perfusion scan. CONCLUSION: MRI is more sensitive than echocardiography for the evaluation of branch pulmonary artery abnormalities in children following surgery for TOF.

Adolescent↗
PubMed1997

The prevalence of selected ocular diseases and conditions.

It is useful for a clinician to know how common or rare a given ocular disease or condition is. Knowledge of a condition's prevalence provides a rough indication of how often to expect to encounter it in a clinical setting. Furthermore, knowledge of a condition's prevalence can assist in planning the health service requirements necessary to treat it. The acquisition of prevalence data from the literature, however, can be difficult and time-consuming because of the wide range of journals that have published relevant information. This article is a complication of some of the available data from the literature regarding the prevalence of many ocular diseases and conditions. It also includes a few systemic diseases with ocular involvement.

Age Distribution↗
PubMed1997

Cancer screening in the older patient.

Effective treatment of several types of malignant diseases has developed substantially over the past four decades, with ever improving survival rates for cancers found in early stages. Among older patients, however, the cancer death rates remain elevated. This article explores the value of early screening for several types of malignant disease in the older patient.

Age Distribution↗
PubMed1997

Pelvic fractures and mortality.

A retrospective study of all patients (N = 343) with pelvic fractures admitted to our trauma service was conducted to evaluate the impact of pelvic fractures on mortality. All patients sustained additional injuries with an average Injury Severity Score (ISS) of twenty. Thirty-six patients died. This group had more severe pelvic fractures as graded by the Tile classification as well as a greater number and severity of associated injuries. Six patients died as a direct result of pelvic hemorrhage. In six other patients, pelvic fractures contributed to their demise. The other twenty-four patients died from brain injury, thoracic hemorrhage, or other non-pelvic causes. Overall mortality for patients with pelvic fractures was 10.5 percent This was a 1.4 fold increase in mortality compared to other trauma patients during the same time period without pelvic fractures. Mortality was dramatically increased in patients over sixty years of age (37 percent mortality compared to 8 percent). This greater than four-fold increase in deaths in the elderly appears to be an age related effect because the elderly patients generally had a lower ISS and less severe pelvic trauma than younger patients. We conclude that sustaining a pelvic fracture places the patient at an increased risk of death. Pelvic fractures contributed directly to death in one-third of the mortalities, one-third died from complications associated with pelvic fractures, and one-third died from other causes.

Accidents, Traffic↗
PubMed1996

The expanding clinical phenotype of the tRNA(Leu(UUR)) A-->G mutation at np 3243 of mitochondrial DNA: diabetic embryopathy associated with mitochondrial cytopathy.

We describe a family which demonstrates and expands the extreme clinical variability now known to be associated with the A-->G transition at nucleotide position 3243 of the mitochondrial DNA. The propositus presented at birth with clinical manifestations consistent with diabetic embryopathy including anal atresia, caudal dysgenesis, and multicystic dysplastic kidneys. His co-twin was normal at birth, but at 3 months of life, presented with intractable seizures later associated with developmental delay. The twins' mother developed diabetes mellitus type I at the age of 20 years and gastrointestinal problems at 22 years. Since age 19 years, the maternal aunt has had recurrent strokes, seizures, mental deterioration and deafness, later diagnosed as MELAS syndrome due to the tRNA(Leu(UUR)) A-->G mutation. A maternal uncle had diabetes mellitus type I, deafness, and normal intellect, and died at 35 years after recurrent strokes. This pedigree expands the known clinical phenotype associated with tRNA(Leu(UUR)) A-->G mutation and raises the possibility that, in some cases, diabetic embryopathy may be due to a mitochondrial cytopathy that affects both the mother's pancreas (and results in diabetes mellitus and the metabolic dysfunction associated with it) and the embryonic/fetal and placental tissues which make the embryo more vulnerable to this insult.

Abnormalities, Multiple↗
PubMed1996

Fos expression in rat visual cortex induced by ocular input of ultraviolet light.

We used immunostaining for the cellular transcription factor Fos to assess patterns of neuronal activation in rat visual cortex during exposure to ultraviolet light. Exposure to monochromatic ultraviolet light (lambda max 360 nm: half-bandwidth 8.8 nm, 10 microW/cm2 at eye level) induced strong expression of Fos immunoreactivity in the primary visual cortex and associated cortical visual areas of dark-adapted rats. The stimulatory effect of ultraviolet light on Fos expression was related to exposure duration, was independent of stimulus novelty or phase of the circadian cycle in which exposure occurred, and it was mediated by a mechanism located in the eye. These results demonstrate that ocular input of ultraviolet light is capable of altering neuronal activity in cortical structures involved in visual processing and are consistent with the hypothesis that rodents may use ultraviolet light for vision.

Animals↗