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B Morgan

Publications and source records attributed to B Morgan.

At least 55 records · Page 3Linked to original sources
PubMed1996

Gene expression in the limbless mutant: polarized gene expression in the absence of Shh and an AER.

Limb buds in the limbless chick begin to form normally but fail to form an AER and ultimately degenerate. Wnt7a and LMX-1, which are restricted to the dorsal half of a normal limb bud, are expressed throughout the ectoderm and mesenchyme of the mutant buds, respectively. Engrailed-1, normally expressed in ventral limb ectoderm, is not expressed in the limbless bud. This defect precedes the normal period of AER formation and no localized expression of genes normally found in the AER is observed in limbless buds. Consistent with the lack of molecular specialization of an AER, Shh and BMP-2 are not expressed in the ZPA of the mutant bud. Despite the lack of Shh, FGF-4, or BMP-2 expression, the hoxd genes are expressed at low levels in the posterior mesenchyme of the bud. Forced expression of Shh fails to rescue the positive feedback loop between the AER and the ZPA and does not lead to distal outgrowth. However, Shh does maintain the part of the bud formed during pre-AER stages. These results support the importance of the dorsal/ventral boundary in the initiation of AER formation and imply that Shh is not required for the initial activation of polarized hoxd gene expression during limb development.

Animals↗
PubMed1996

Biliary distensibility during per-operative cholangiography as compared to pre-operative ultrasound: a four year follow-up study.

INTRODUCTION: It is well recognized that corrected bile duct diameters, as measured by endoscopic retrograde cholangiography (ERC), are often significantly greater than the corresponding ultrasound measurement. This can be attributed to variation in bile duct distensibility and is particularly noted in post cholecystectomy patients, possibly due to loss of the gall bladder reservoir effect. It has been suggested that increased bile duct distensibility may be related to the post-cholecystectomy syndrome. We have observed a similar discrepancy between ultrasound and per-operative cholangiography (POC). This trial investigates whether the discrepancy between ultrasound and POC measurements has clinical significance. METHOD: Seventy-five patients with normal pre-operative ultrasound and POC undergoing standard open cholecystectomy (with benzodiazepine pre-medication) in 1990 were identified. After allowance for magnification, maximum biliary diameters were obtained for the proximal extra-hepatic bile duct. Follow-up was obtained in 67 patients from clinical case notes and contact with general practitioners. RESULTS: Considerable variation of bile duct distensibility was recorded (range 83% to 410%) with 12 cases having POC biliary diameters outside radiological guidelines (12 mm as recorded on the radiograph). This distension is shown to increase with age. After 4 years, 16 patients had recurrent abdominal pain of which nine had undiagnosed right upper quadrant pain. There were no clinical cases of retained stone post-operatively. There was no correlation between POC measured bile duct diameter or distensibility and post-operative or long term problems. This study suggests that the bile duct has a normal variation of distensibility which increases with age and that radiological guidelines, as regards the upper limit for normal POC biliary diameters can be relaxed.

Adult↗
PubMed1996

Hypertrophic osteoarthropathy in staging skeletal scintigraphy for lung cancer.

AIM: To assess the prognostic significance of hypertropic osteoarthropathy (HOA) discovered on routine staging bone scintigraphy in patients with lung cancer. PATIENTS AND METHODS: Between 1989 and 1992 all 99mTc-MDP bone scintigrams performed for the staging of bronchogenic carcinoma were reviewed. HOA was diagnosed by the observation of cortical/periosteal increased uptake in the extremities of the long bones. Follow-up and confirmation of the diagnosis was obtained by hospital computer, histology records, operative records, patient notes and radiological data where available. RESULTS: 164 staging scintigrams for lung cancer were identified. Twenty-eight patients (17%) were observed to have HOA. Patients with and without HOA were well matched for age and sex. There was little difference in the distribution of cell type but the HOA groups has a greater incidence of peripheral tumours. There was no significance in survival between the two groups. Two of three long-term survivors had clinically overt HOA and one presented with arthralgia. CONCLUSION: HOA is often seen on skeletal scintigraphy for staging of lung cancer and has no prognostic significance. The data also support current teaching that a high index of suspicion for HOA, as a cause of arthralgia may lead to early diagnosis of a potentially resectable lung carcinoma.

Aged↗
PubMed1996

Snoring as part of a dose-response relationship between sleep-disordered breathing and blood pressure.

This report addresses the hypothesis that snoring without significant apneas and hypopneas (simple snoring) is associated with elevated blood pressure and cardiovascular disease (CVD). Data on blood pressure, previously diagnosed cardiovascular disease, and sleep-disordered breathing (SDB) status from a population-based sample of 580 adults was analyzed. Systolic and diastolic blood pressures, adjusted for age, sex, and body mass index, increased stepwise across categories of no SDB, simple snoring, mild, moderate, and more severe SDB (p < 0.05). A similar and significant trend was seen for CVD prevalence. The results provide evidence that simple snoring represents the beginning of the SDB severity spectrum and that simple snoring has a proportionately smaller but, nevertheless, significant, risk for elevated blood pressure and CVD.

Adult↗
PubMed1996

The correlation of bone scintigraphy and histological findings in patellar tendinitis.

Patellar tendinitis is a chronic overuse injury causing pain and tenderness over the proximal insertion of the patellar tendon. Its management is usually conservative, but in intractable cases surgery is effective. Bone scintigraphy has been suggested as a useful investigation in these patients, although we are aware of no large series supporting this. Thirty-four patients with intractable symptoms of patellar tendinitis were treated surgically. The operative specimens were graded histologically and compared with preoperative radionuclide bone scans. The histological findings confirmed tendon and or tendon sheath abnormalities in all the samples. The predominant abnormalities were increased vascularity, fibroblast proliferation, acid mucopolysaccharide and haemosiderin deposition. Bone scintigraphy showed 24 (71%) patients to have abnormalities on the delayed images, 8 with diffusely increased activity in the patella and 16 with increased activity localized to the lower pole. Patients with abnormal bone scans had significantly more severe histological changes in their tendons. These findings support the use of radionuclide bone scans in the pre-operative assessment of patellar tendinitis correlating well with histopathological severity of the disease process. The 10 false-negative cases (29%), however, suggest that bone scans are unhelpful in the routine diagnosis and management of this condition.

Adolescent↗
PubMed1995

Using a mixture model to predict the occurrence of diabetic retinopathy.

Diabetes mellitus is a common condition which has several serious complications associated with it. In this paper a mixture model, based on one previously used to predict the onset of AIDS, is used to predict the onset of one of these complications, diabetic retinopathy, the major cause of adult blindness in the U.K. This model differs from the previous AIDS model by introducing covariates into the model and using a wider choice of mixture distributions. The fit and distributional assumptions of the model are then discussed for this example. The model is fitted to the data by maximum likelihood. It is important that the training set contains balanced numbers of individuals with and without retinopathy.

Acquired Immunodeficiency Syndrome↗
PubMed1995

Effect of age on myocardial infarction and thrombolysis.

Thrombolytic therapy has emerged as the treatment of choice for patients presenting with an acute myocardial infarction. Myocardial infarction is a major cause of morbidity and mortality in the elderly. Advancing age has been considered a relative contraindication to thrombolytic therapy despite the potential for the elderly to derive the greatest benefit from this therapy. This trend not to treat the elderly has been based on a perceived increased risk of complications. Available data pooled from several studies clearly show that the elderly benefit from thrombolytic therapy.

Aged↗
PubMed1995

Hypertension and sleep apnoea.

Epidemiological data indicate a link between sleep-disordered breathing and elevation of arterial pressure. Previous studies suggest increased activity of the sympathetic nervous system in patients with sleep apnoea. The response of muscle sympathetic nerve activity was further investigated in normal, awake subjects following exposure to 20 minutes of asphyxia. Sympathetic nerve traffic increased during exposure and remained elevated even after the return to room air breathing. These findings raise the possibility that this sustained elevation of sympathetic nerve traffic could play a role in the development of daytime hypertension in patients with sleep-disordered breathing.

Journal Article↗
PubMed1995

Blood pressure changes during labour and whilst ambulating with combined spinal epidural analgesia.

OBJECTIVE: To determine the influence of combined spinal epidural analgesia with fentanyl and low dose bupivacaine on maternal blood pressure and pulse rate in labour. Also, to evaluate the maternal cardiovascular response to mobilising with this form of analgesia in labour. Finally, to define the changes that occur in blood pressure and pulse rate during the second stage of labour and immediately postpartum when using combined spinal epidural analgesia. DESIGN: A prospective observational study. SUBJECTS AND METHODS: Blood pressure and pulse measurements were made at least every 10 minutes, using the SpaceLabs 90207 ambulatory blood pressure monitor, on 62 women in labour with combined spinal epidural analgesia. RESULTS: A significant fall in systolic blood pressure (> 20%) occurred in eight women (12%), all within 30 minutes of the spinal injection. Fifty-two women subsequently received an epidural dose (mean interval 90 minutes after spinal) and none of these women had a fall in systolic blood pressure of greater than 20%. No women had symptoms related to hypotension. Thirty-five women ambulated for more than 10 minutes on 65 occasions. Average blood pressure remained unchanged while ambulating (126/79 versus 126/79), but pulse rate was significantly increased (85 to 90, P < or = 0.001). The mean blood pressure in the second stage of labour (n = 41) did not rise with pushing (134/83 versus 134/83), but the pulse rate increased significantly (94 to 108, P < or = 0.001). Blood pressure remained unchanged immediately postpartum (n = 33) (134/83 versus 134/81) following ergometrine administration. CONCLUSION: The combined spinal epidural analgesia will only result in significant falls in systolic blood pressure within 30 minutes of the spinal injection. No further important changes in blood pressure occur when mobilising or with epidural top-ups. The combined spinal epidural analgesia may modify the normal compensatory mechanisms of blood pressure control, but does not cause significant maternal hypotension once the spinal injection has been given.

Analgesia, Epidural↗
PubMed1994

A novel and major isoform of tyrosine hydroxylase in Drosophila is generated by alternative RNA processing.

We report that two isoforms of Drosophila tyrosine hydroxylase protein are encoded via alternatively spliced exons. The major isoform (Type II) contains a novel acidic extension of 71 amino acids in the amino-terminal regulatory domain, which is likely to alter the regulatory properties of the tyrosine hydroxylase protein. The minor isoform (Type I) corresponds to the cDNA sequence reported previously. We also report the structure of the Drosophila tyrosine hydroxylase (DTH) gene and the diversity and tissue localization of its transcripts. At least three types of DTH mRNA are generated from a single primary transcript through alternative splicing and polyadenylation. Type II mRNA is the most abundant tyrosine hydroxylase transcript in Drosophila and is found predominantly in the hypoderm throughout all stages of development. Type I mRNA is present only in the CNS, where it is the primary form. The DTH transcripts detected in the CNS contain a longer 3'-untranslated region than the transcript expressed in the hypoderm, due to differential polyadenylation. In contrast, the same start site is used for DTH gene transcription in both tissues. These results show unexpected diversity in the DTH transcripts and point out possible mechanisms for differential regulation of tyrosine hydroxylase activity in the CNS and in the hypoderm.

Alternative Splicing↗
PubMed1994

Spying on mothers.

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Airway Obstruction↗