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Biomedical subjects

B D White

Publications and source records attributed to B D White.

At least 19 recordsLinked to original sources
PubMed2005

Corpus callosum changes following shunting for hydrocephalus: case report and review of the literature.

Diffuse callosal signal changes can rarely occur following successful shunting for obstructive hydrocephalus. We report on a patient who underwent ventriculoperitoneal shunting for aqueductal stenosis and required two revisions for neurological deterioration and presumed shunt malfunction. Extensive changes involving the corpus callosum, periventricular white matter and optic chiasm were noted after the first, and were prominent after second shunt revision. Thus, post-shunting callosal changes may be associated with more extensive white matter disease, and may not imply wide pressure fluctuations. However, they need not prompt further intervention.

Adult↗
PubMed2005

To graft or not to graft: rationalizing choice in anterior cervical discectomy.

Anterior cervical discectomy has been performed for almost 50 years. Initially, bone grafts were used routinely, but soon their necessity was questioned. It remains disputed to this day. The aim was to establish whether there are grounds for basing choice of technique on individual patient data. The cervical spine radiographs of 148 patients who had undergone grafted or ungrafted anterior cervical discectomy were reviewed and changes in geometry at the operated level were measured. These data were then examined for any correlation between preoperative geometry, choice of operative technique and adverse clinical outcome. Disturbances to spinal geometry after ungrafted discectomy are minimal at disc heights below 4 mm. At and above 4 mm significant settlement and angulation occur. Complications in our series were fewer where small disc spaces were left ungrafted and larger ones grafted. Disc spaces below 4 mm should not be grafted, but spaces of 4 mm or more should.

Bone Transplantation↗
PubMed2005

Computed tomography diagnosis of tracheobronchopathia osteochondroplastica.

Tracheobronchopathia osteochondroplastica (TO) is a rare benign disease characterized by the presence of osseous and cartilaginous submucosal nodules projecting into the tracheobronchial tree. Most cases are asymptomatic and discovered incidentally at post-mortem. We identified a case of TO on thoracic spiral CT and confirmed the diagnosis of bronchoscopy. This article reviews the imaging characteristics of TO, and shows the 3-D virtual bronchoscopic and multiplanar reconstruction appearances of TO.

Bronchial Diseases↗
PubMed2004

Idiopathic anterior spinal cord hernia: under-recognized cause of thoracic myelopathy.

Until recently, idiopathic anterior spinal cord herniation was thought to be vanishingly rare. It is an increasingly recognized, readily treatable, condition causing progressive thoracic myelopathy. We have operated on five cases and know of two other patients locally who are as yet undecided on surgery. We are aware of several other unpublished cases in the UK. The syndrome presents typically in middle age with a history of stepwise slowly progressive mid-thoracic anterior hemicord dysfunction characterized by hemianalgesia below the affected segment followed by asymmetric lower limb hypertonia, with initial sparing of posterior column sensation, that progresses through paraparesis to complete paraplegia. The radiological findings, although subtle, are equally typical and surgical repair is easily effected. With increasing clinical and radiological awareness, we believe the apparent incidence of this condition will increase. Idiopathic anterior spinal cord hernia is more common than currently appreciated, and should be positively considered and excluded in every case of progressive thoracic cord dysfunction.

Aged↗
PubMed2003

Low dietary protein is associated with an increase in food intake and a decrease in the in vitro release of radiolabeled glutamate and GABA from the lateral hypothalamus.

Moderately low-protein diets lead to a rapid increase in food intake and body fat. The increase in feeding is associated with a decrease in the concentration of serum urea nitrogen, suggesting that the low-protein-induced increase in food intake may be related to the decreased metabolism of nitrogen from amino acids. We hypothesized that low dietary protein would be associated with a decrease in the synaptic release of two nitrogen-containing neurotransmitters, GABA and glutamate, whose nitrogen can be derived from amino acids. In this study, we examined the effects of a low-protein diet (10% casein) in Sprague-Dawley rats on the in vitro release of 3H-GABA and 14C-glutamate from the lateral and medial hypothalamus. The low-protein diet increased food intake by about 25% after one day. After four days, the in vitro release of radiolabeled GABA and glutamate was assessed. The calcium-dependent, potassium-stimulated release of radiolabeled GABA and glutamate from the lateral hypothalamus was decreased in rats fed the low-protein diet. The magnitude of neurotransmitter release from the lateral hypothalamus inversely correlated with food intake. No dietary differences in the release of neurotransmitters from the medial hypothalamus were observed. These results support the contention that alterations in nitrogen metabolism are associated with low-protein-induced feeding.

Ammonia↗
PubMed2002

A subdural haematoma following 'reverse' bungee jumping.

Bungee jumping has been exploited commercially for 13 years and proprietors claim a good safety record. However, published case reports document a wide variety of possible injuries. To this list, we add a report of a subdural haematoma sustained during a variant of the sport, the 'reverse' bungee jump.

Adult↗
PubMed2001

Telephone advice for neurosurgical referrals. Who assumes duty of care?

The rising rate of litigation against all specialities provides an incentive to develop risk management strategies. Much of a neurosurgeon's workload is telephone advice, which is rarely documented formally. This leaves us vulnerable to other clinicians' interpretation of our advice, their record of our conversation and poor accuracy of recall by both parties. We performed a prospective study of all telephone conversations with referring clinicians over 1 year, in order to assess the quality of information transfer. We found that the information received was often inaccurate, documentation of our given advice was poor, and criticism of neurosurgical care was unfounded. We have developed a proforma to be faxed back to the referring team. This will ensure that the information received, and the advice given in return, is recorded formally by both teams. Only time will tell if a joint record such as this will provide sufficient defence against litigation.

Adolescent↗
PubMed2000

Effects of age on the feeding response to moderately low dietary protein in rats.

Moderately low levels of dietary protein are associated with increased food intake and body fat. We propose that the generation of this feeding signal is dependent on the level of dietary protein relative to the protein requirement of the animal, that is, that protein-dependent feeding is maximized when the level of dietary protein is around the animal's protein requirement. One of the factors that affects an animal's protein requirement is age. We predict that young, growing animals are more responsive to a moderately low level of dietary protein than are mature animals. The feeding response to moderately low dietary protein (10% casein) was determined in young ( approximately 190 g) and more mature ( approximately 340 g) Sprague-Dawley rats for 12 days. As an index of amino acid deamination, serum urea nitrogen concentrations were determined, as was the in vitro release of neuropeptide Y (NPY) from hypothalamic tissue containing the paraventricular nucleus. Young rats were more responsive to the feeding effects of moderately low dietary protein than mature animals. In young rats, cumulative food intake was inversely correlated with serum urea nitrogen concentration. No correlation was found in mature animals. Although the amount of NPY remaining in hypothalamic tissue after incubation was significantly greater (p = 0.04) in young rats fed 10% casein as compared with rats fed the standard 20% casein diet, no dietary difference in K(+)-stimulated NPY release was observed. We hypothesize that the signal for low-protein-induced hyperphagia is a reduction in a compound whose production is coupled to the level of amino acid deamination in the brain.

Aging↗
PubMed2000

Food intake, energy balance and serum leptin concentrations in rats fed low-protein diets.

Studies examining the effects of low-protein diets on food intake and body weight have shown varied results. Many researchers have found low dietary protein to increase food intake, while others have found no effect or even a decrease. In 63 male Sprague-Dawley rats, we examined several low levels of dietary protein (2%, 5%, 8%, 10%, 15% vs. 20% casein) to determine the dose-response relationships between low dietary protein and food intake, body composition, energy balance and serum leptin concentrations. Food intake, over the range of low dietary protein, showed a quasi bell-shaped response curve with peak intake occurring in rats fed 8-10% casein. Peak feeding occurred at or just below the estimated protein requirement of the rats (10-12.5% casein). Compared to the 20% casein controls, food intake was severely reduced in rats fed 2% casein, while it was greater in the other low-protein groups. The amount of body fat steadily increased between the 15% casein group and the 8% casein group, and sharply declined between the 5% casein group and 2% casein group. The change in body fat reflected both the change in food intake and altered energy partitioning. Serum leptin concentrations were greater in rats fed the 5 and 8% casein diets than in control rats fed 20% casein. Serum leptin concentrations were positively associated with body fat content (r(2) = 0.763, P < 0.001). Increased serum leptin concentrations in the presence of increased food intake is suggestive of a state of leptin resistance. This animal model may provide important insights into diet-induced obesity.

Ammonia↗
PubMed1998

Neuropeptide Y antibody attenuates 2-deoxy-D-glucose induced feeding in rats.

2-deoxy-D-glucose (2-DG) has been shown to induce increased feeding responses in animals. Recent studies suggest the possible involvement of neuropeptide Y (NPY) in 2-DG-induced feeding. The present study examined the effect of immunoneutralization of endogenous NPY on 2-DG-induced feeding. NPY antibody injected into the paraventricular nucleus of the rats significantly attenuated 2-DG-induced feeding, suggesting that hypothalamic NPY may mediate, at least partly, the effect of 2-DG on food intake.

Animals↗
PubMed1998

'Safe neurosurgery'. How are we doing three years on?

'Safe Neurosurgery' a document setting out standards of practice in British neurosurgery was published in 1993. Three years later we have looked at how much of an impact this extremely important document has made. We have been disappointed to discover that overall there has been little change for the better. The paper illustrates the changes seen over the 3 years.

Bed Occupancy↗
PubMed1998

Longer-term fourth ventricular 5-thioglucose infusion increases body fat in the rat.

5-Thioglucose (5-TG) has been shown to increase food intake after acute administration. To determine the longer-term effects of 5-TG on feeding and body composition, thirty-four female Sprague-Dawley rats were cannulated into the fourth ventricle and infused with artificial CSF and either 0.01 M 5-TG or 0.1 M 5-TG using osmotic pumps. Food intake and body weight were monitored daily. Rats were killed after 14 days of infusion. Carcass and fatpad weights were measured, and body compositions were determined. Food intake was not different during the first week of infusion; however, cumulative food intake was decreased in the 0.1 M 5-TG group during the second week as compared to the CSF control group. Body weight and carcass weight of this group also decreased as compared to the control. The group receiving the higher dose of 5-TG (0.1 M) had increased fatpad weights in all three depots examined (inguinal, retroperitoneal, and perimetrial depot); the group with lower dose of 5-TG infusion (0.01 M) increased the fatpad weights in the retroperitoneal and perimetrial depot, as compared to the CSF group. Data from the body composition analysis were consistent with the results of the fatpad weights. In conclusion, the present study demonstrated that chronic fourth ventricular 5-TG infusion increased body fat without increasing food intake, suggesting that energy expenditure is decreased under this condition. The results of this study indicate that glucose metabolism in the hindbrain is important in the control of energy expenditure, body fat deposition, and thus energy balance regulation.

Adipose Tissue↗
PubMed1997

Elevated hypothalamic neuropeptide Y levels in rats with dorsomedial hindbrain lesions.

Lesions centered on the area postrema (AP) and adjacent nucleus of the solitary tract (AP/mNTS-lesions) are reported to result in increased consumption of highly palatable diets. Recent studies suggest that neuropeptide Y (NPY) may cause a preference for carbohydrate-rich diets. Thus, it is possible that NPY may play a role in the enhanced intake of highly palatable diets by AP/mNTS-lesioned rats. In the studies reported here, we found that lesions centered on the AP result in increased levels of NPY-immunoreactivity in the paraventricular nucleus of the hypothalamus. Additionally, steady-state NPY mRNA in the basomedial hypothalamus including the arcuate nucleus was elevated. Enhanced NPY was not found throughout the hypothalamus however, as NPY-immunoreactivity was not elevated in the lateral hypothalamus or the tissue bordering the anteroventral third ventricle. These data suggest the possibility that elevated hypothalamic NPY, particularly in the arcuate and paraventricular nuclei, may contribute to the altered food intake and energy balance observed in rats with lesions centered on the AP.

Animals↗
PubMed1997

Evidence for a central mechanism of obesity in the Zucker rat: role of neuropeptide Y and leptin.

Thirty-five years ago, Lois and Theodore Zucker reported the discovery of a genetic mutation in the rat that resulted in juvenile-onset obesity, increased food intake, decreased energy expenditure, and insulin resistance. The mutation was called fatty (fa). The fatty gene is passed on to successive generations by an autosomal recessive mode of inheritance. In the intervening years, much work has been done to characterize the many abnormalities of this animal model of obesity. Nearly 10 years ago, we reviewed the evidence for a central nervous system mechanism in the etiology of obesity in the fatty Zucker rat. Since that time, the discovery of novel peptides and genes has revolutionized the study of the etiology of genetically linked obesities. In this review, we update the evidence for a central nervous system mechanism of obesity in Zucker rats by focusing on the possible role of neuropeptide Y (NPY) and leptin in the etiology of obesity. We also discuss the role of glucocorticoids and insulin in the regulation of NPY.

Animals↗
PubMed1996

Interaction of type I and type II corticosteroid receptor stimulation on carcass energy and carcass water.

The effects of chronic type I and type II corticosteroid receptor stimulation were examined in adrenalectomized Sprague-Dawley rats to quantify the relative contribution of body energy and body water changes to changes in body weight. Adrenalectomy caused a decrease in both body energy and water. Aldosterone (type I agonist) treatment increased body weight gain and returned energy accretion to the level of sham-operated animals. However, most of the change in body weight (72%) was attributable to a change in body water. The aldosterone-induced increase in body weight gain and carcass water were attenuated by RU-28362 (type II receptor agonist) infusion, suggesting that type II receptor stimulation can antagonize the effect of type I receptor stimulation. Changes in carcass water were paralleled by changes in soluble carcass sodium. Despite alterations in soluble body sodium, no measurable differences in cumulative sodium retention were found. These findings confirm previous studies suggesting an effect of type I receptor stimulation on energy accretion. However, they also caution that changes in body weight cannot be equated with changes in body energy.

Adrenalectomy↗