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Biomedical subjects

S Bavetta

Publications and source records attributed to S Bavetta.

16 recordsLinked to original sources
PubMed2005

The two-week waiting time standard for cancer: a neurosurgical perspective.

The implementation of the two-week wait initiative for cancer referrals in the NHS has had a major impact on outpatient services. A low clinical detection rate among GPs for neurological cancer has resulted in a large number of urgent referrals with a low yield of positive diagnoses. We have devised a strategy for minimizing the impact on outpatient clinics: patients are scanned prior to clinical review and those with normal scans are referred back to the GP without a clinic appointment. Out of 69 referrals of suspected CNS cancer made in 2003, 61 were scanned and six resulted in a positive diagnosis. The equivalent of 10 clinics was saved, and an increased speed of diagnosis and treatment was achieved with no compromise in patient care. Our study illustrates the consequences of the 2-week wait initiative on the neurosurgical service, and proposes an effective and safe solution.

Attitude of Health Personnel↗
PubMed2003

Trigeminal neuralgia presenting as Chiari I malformation.

Chiari I malformation usually presents with headache, numbness, weakness and gait abnormalities. We present a 38-year-old female with trigeminal neuralgia who was found to have a Chiari I malformation. She had a foramen magnum decompression with complete resolution of her symptoms.

Adult↗
PubMed2002

Assessment and management of the head-injured patient.

Head injury is one of the most important causes of serious morbidity and mortality in young adults. Each year in Britain, there are approximately 5000 deaths from serious head injuries. Appropriate multidisciplinary assessment and management of systemic and intracranial pathology can significantly improve the outcome.

Adult↗
PubMed1999

Spontaneous axonal regeneration after optic nerve injury in adult rat.

Optic nerves of adult rats were crushed 2 mm behind the eye to examine the ability of retinal ganglion cells (RGCs) to regenerate their axons. Some animals were treated with the immunophilin ligands FK 506 or GPI 1046 for up to 4 weeks. After 10 days to 16 months, regenerating RGC axons were visualized using anterograde tracing and/or electron microscopy. A small proportion of RGC axons regenerated across the lesion site and grew very slowly along the entire optic nerve. Immunophilin ligands had no obvious effect. The regenerating axons were about 0.2 microm in diameter, and usually in clusters surrounded by astrocyte processes. Thus, some CNS axons can spontaneously regenerate long distances within degenerate white matter and this slow regeneration is not accelerated by immunophilin ligands.

Animals↗
PubMed1999

The effects of FK506 on dorsal column axons following spinal cord injury in adult rats: neuroprotection and local regeneration.

There is considerable evidence that immunophilin ligands can promote the regeneration of axons in peripheral nerves and act as neuroprotective agents in the CNS. We have examined the effects of FK506 and GPI 1046 on the responses to partial transection of ascending spinal dorsal column axons at T9, in some cases combined with crush of one sciatic nerve. FK506 (0.5 or 2.0 mg/kg) and GPI 1046 (10 or 40 mg/kg) was administered subcutaneously immediately after surgery and five times a week thereafter. Some animals received methylprednisolone (MP) (two subcutaneous doses of 30 mg/kg) in addition to, or instead of, FK506. After survival times of 1-12 weeks, dorsal column axons were labeled transganglionically with cholera toxin B-HRP. There was massive axonal sprouting at the lesion sites in animals with sciatic nerve injury and immunophilin ligand treatment. In FK506-treated animals a few severed sensory axons regenerated for up to 10 mm rostral to the lesion. Of greater significance, 30% of 71 FK506-treated animals had spared axons in the dorsal column, extending to the nucleus gracilis, versus 8% of 50 control animals (P < 0.05), showing that FK506 reduces the likelihood of axonal destruction due to secondary injury. A combination of FK506 and MP afforded greater protection than MP alone (P < 0.05), but axonal survival was not affected by sciatic nerve crush, dose of FK506, or survival time after injury. GPI 1046 (n = 11) did not promote axonal survival. Thus FK506 protects axons from secondary injury following spinal cord trauma, and in this experimental model, its neuroprotective effect is greater than that of MP.

Animals↗
PubMed1998

Nitric oxide synthase is co-localized with vasoactive intestinal polypeptide in postganglionic parasympathetic nerves innervating the rat vas deferens.

Cross-sections of the vas deferens taken from control adult male rats showed positive histochemical reactivity to acetylcholinesterase and immunoreactivity for antibodies to protein gene product 9.5, tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, nitric oxide synthase and calcitonin gene-related peptide. Immunoreactivity to substance P was very sparse. Histochemical reactivity to acetylcholinesterase and immunoreactivity to vasoactive intestinal polypeptide and nitric oxide synthase was concentrated in the subepithelial lamina propria and inner smooth muscle layers. Complete surgical denervation resulting from transection of the nerve arising from the pelvic ganglion which supplies the vas deferens totally abolished the immunoreactivity to all of the antibodies tested as well as the histochemical reactivity to acetylcholinesterase. In sections of the prostatic end of the vas deferens taken from rats neonatally pretreated with capsaicin, immunoreactivity to calcitonin gene-related peptide and substance P was reduced by 75 and 83%, respectively. Immunoreactivity to neuropeptide Y, vasoactive intestinal polypeptide and nitric oxide synthase was similar in tissue sections taken from capsaicin-treated rats and those taken from control tissues. Pretreatment of rats with guanethidine or 6-hydroxydopamine decreased immunoreactivity to tyrosine hydroxylase and neuropeptide Y by 60-70%, but immunoreactivity to substance P, vasoactive intestinal polypeptide and nitric oxide synthase was unchanged, while immunoreactivity to calcitonin gene-related peptide and acetylcholinesterase staining was increased by guanethidine but not by 6-hydroxydopamine treatment. Triple labelling experiments showed nitric oxide synthase, vasoactive intestinal polypeptide and acetylcholinesterase all to be co-localized in some nerve fibres. These results indicate that the nitric oxide synthase contained in the nerve fibres innervating the rat vas deferens is unaffected by pretreatment of rats with capsaicin, 6-hydroxydopamine or guanethidine but is abolished by surgical denervation, of postganglionic parasympathetic, sympathetic and sensory nerves. Therefore it appears that nitric oxide synthase is co-localized with vasoactive intestinal polypeptide in the postganglionic parasympathetic nerves which innervate the rat vas deferens.

Animals↗
PubMed1997

Prospective study of zero drift in fiberoptic pressure monitors used in clinical practice.

One hundred and one fiberoptic pressure transducers (59 subdural and 42 ventricular) were studied in 86 patients (some in whom more than one device had been inserted). Only four complications occurred: two transient cerebrospinal fluid leaks after removal and two clinically insignificant intracerebral hematomas. No intracranial infections could be attributed to the devices. Technical problems occurred 23 times, with 11 devices ceasing to function before removal, seven becoming displaced, and five microventricular catheters failing to enter the ventricles. Zero-drift readings were obtained for 83 devices at the time of removal (median 66 hours after insertion, range 2 hours-13 days). There was a clear negative bias in the readings (median -3), with a wide range of values (-12 to +14 mm Hg; interquartile range -6 to -1) that was apparent even in the first 3 days of use. There was no important relationship between zero drift and any recorded variable. It is concluded that zero drift of fiberoptic pressure transducers is a significant problem and that undue reliance should not be placed on intracranial pressure readings from these devices in isolation from other clinical and radiological information.

Equipment Failure↗
PubMed1996

A prospective comparison of fibre-optic and fluid-filled single lumen bolt subdural pressure transducers in ventilated neurosurgical patients.

A clinical comparison was made between fibre-optic and fluid-filled Bolt subdural pressure transducers in ventilated head injured patients. Twelve subjects had both devices inserted in neighbouring sites. In two patients there were obvious technical problems with the fibre-optic system and the results were therefore excluded from further analysis. In the remaining 10 patients, 2167 pairs of simultaneous recordings were made for up to 9 days and the degree of correspondence studied. A quarter of paired readings differed by more than 5 mmHg. There was no evidence of any overall bias, but in individual patients one device often read higher or lower than the other. The proportion of closely corresponding readings tended to diminish after 4 days. Therapeutically relevant episodes, where treatment might have been initiated on the basis of the readings from only one of the two systems, were equally likely with both devices and occurred on average approximately every 30 h. The relative accuracy of the two devices remains uncertain, but there is evidence suggesting that both were prone to errors.

Adolescent↗
PubMed1996

Neurenteric cyst of the anterior cranial fossa.

Neurenteric cysts are uncommon developmental cysts of the central nervous system lined by epithelium of intestinal origin. We describe a cyst in the anterior cranial fossa, which has not been previously reported.

Adult↗
PubMed1994

A prospective study comparing SPET with MRI and CT as prognostic indicators following severe closed head injury.

Ten patients were studied prospectively afer severe closed head injury to determine the relationship between long-term clinical outcome and abnormalities detected by single photon emission tomography (99Tcm-HMPAO SPET), CT and MRI obtained within 60 days of injury. The ability of SPET to detect abnormalities not visualized by CT or MRI after cerebral trauma by the results of this study. Changes detected by SPET [global cerebral blood flow (gCBF) and number of regional cerebral blood flow (rCBF) deficits] soon after trauma were shown to be more closely correlated with long-term outcome than changes detected by MRI or CT. Templates were used to classify lesions by site and a multivariate analysis was undertaken to establish the importance of defect position in predicting clinical outcome. The results suggest that lesions in the temporal lobes, frontal lobes and basal ganglia are related to poor prognosis, and that SPET yields more useful prognostic data than the other methods.

Adult↗
PubMed1990

Spreading sepsis by cystoscopy.

A healthy 54 year old man was investigated for haematuria. In spite of a proven urinary tract infection a cystoscopy was carried out with no antibiotic therapy. As a result he developed systemic infection leading to two independent, and potentially fatal, complications: vertebral osteomyelitis and a mycotic false aneurysm.

Aneurysm, Infected↗
PubMed1983

Duration of the calcium signal in the mitogenic stimulation of thymocytes.

An increase in the free cytoplasmic Ca2+ concentration in thymocytes can be detected by the fluorescent indicator quin 2 within a few seconds of the addition of concanavalin A and the response is quantified from the increased proportion of quin 2 in the cells chelated by Ca2+ ('% Ca-quin 2'). The % Ca-quin 2 in untreated cells is 53 +/- 6%, increases to 64 +/- 7% immediately after the addition of concanavalin A and declines spontaneously over 24 h back to the level in untreated cells (53 +/- 6%). The increase in % Ca-quin 2 in response to concanavalin A is completely blocked when 50 mM-alpha-methyl D-mannoside is added before concanavalin A and completely reversed when the competing sugar is added immediately after the mitogen. Addition of alpha-methyl D-mannoside at increasing intervals after concanavalin A addition causes a progressively smaller decrease in % Ca-quin 2 and has a negligible effect after 24 h, when the % Ca-quin 2 is the same as that in untreated cells. The decline in the calcium signal defined by these experiments has a similar time course to cap formation by concanavalin A on the cells. It is concluded that the calcium signal lasts only while concanavalin A is bound to the cell surface and is terminated either by capping or by the addition of alpha-methyl D-mannoside.

Aminoquinolines↗
PubMedDate not supplied

Brain injury without head injury after multiple trauma.

Watershed infarction has previously been described after cerebral trauma, when it is due to raised intracranial pressure or systemic hypotension. A case is reported, so far as is known for the first time, of bilateral watershed infarction following blunt systemic trauma, without injury to the head or neck. The importance of resuscitation in preventing secondary brain injury caused by systemic hypotension is highlighted. The advantages of HMPAO-SPET in detecting cerebral perfusion defects are discussed.

Adult↗