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Biomedical subjects

P Marks

Publications and source records attributed to P Marks.

At least 55 records · Page 3Linked to original sources
PubMed1994

Bradykinin, coronary artery disease and gastro-oesophageal reflux.

Gastro-oesophageal reflux and coronary artery disease frequently coexist. Stimulation of myocardial vagal receptors impairs lower oesophageal sphincter (LOS) function and may explain this link. This study examined the role of bradykinin, produced in increased quantities by the ischaemic myocardium, in activating this reflex. Thirteen dogs had patches soaked in bradykinin 100 micrograms/ml and saline applied sequentially to the left ventricular epicardium. Eleven of these animals were further divided into two subgroups: group 1 animals (six dogs) had the above sequence repeated after obliteration of sympathetic afferent fibres with phenol and those in group 2 (five animals) underwent sequential intravenous and intra-atrial injection of bradykinin 0.2 micrograms/kg. Epicardial bradykinin produced a fall in mean(s.e.m.) LOS tone from 13.3(1.3) to 6.0(0.5) sphinctometer units (P < 0.002), accompanied by a reduction in mean(s.e.m.) arterial pressure from 95(4) to 83(5) mmHg (P < 0.002). Destruction of sympathetic afferent fibres did not alter the LOS effect. Intra-atrial, but not intravenous, bradykinin reproduced the LOS effect; this suggests a cardiac origin. Myocardial release of bradykinin may play a role in producing transient LOS relaxation, predisposing to gastro-oesophageal reflux.

Animals↗
PubMed1994

Hypotension induced by haemorrhage impairs lower oesophageal sphincter function.

The effect of haemorrhage-induced hypotension on lower oesophageal sphincter (LOS) tone was studied in 11 adult mongrel dogs. Mean(s.e.m.) blood loss of 760(66) ml, corresponding to 42 per cent of estimated blood volume, was associated with a significant fall in LOS tone (14.2(1.0) versus 7.2(0.6) sphinctometer units, P < 0.002). This was associated with a reduction in mean(s.e.m.) arterial blood pressure (99(7) versus 53(3) mmHg, P < 0.002) and heart rate (113(6) versus 106(5) beats per min, P = 0.06). Group 1 animals (n = 6) received autotransfusion, restoring LOS tone to prehaemorrhage values. Dogs in group 2 (n = 5) were given intravenous erythromycin 4 mg/kg, which also restored LOS tone. This effect was transient, lasting a mean(s.e.m.) of only 67(7) min. Infusion of an equivalent volume of 0.9 per cent saline following cessation of the erythromycin effect restored LOS tone to control values although the animals remained hypotensive. Reduction in LOS tone with haemorrhage may be part of a vagal reflex mediated by myocardial afferent C fibres and may explain the high incidence of pulmonary aspiration in shocked patients.

Animals↗
PubMed1994

Adhesions after laparoscopic inguinal hernia repair. A comparison of extra versus intra peritoneal placement of a polypropylene mesh in an animal model.

Prosthetic mesh for laparoscopic inguinal hernia repair has become popular but the method of its placement is controversial. Mesh placed within the peritoneum may cause adhesion formation and further complications. The aim of this study was to examine the laparoscopic placement of a mesh, comparing intraperitoneal vs extraperitoneal insertion. In a porcine model (n = 15) a polypropylene mesh was placed laparoscopically over the anterior abdominal wall. On the left side the mesh was stapled on the parietal peritoneum. On the right side the peritoneum was incised, an extraperitoneal space was dissected, the mesh was inserted, and the peritoneum was closed over it. The animals were maintained for 2 weeks. At postmortem there were adhesions in two of those placed extraperitoneally and five of those placed intraperitoneally (P = 0.19, Fisher's exact test). The adhesions comprised fibrous peritoneal bands to loops of small intestine. Both methods of laparoscopic mesh placement were associated with a small but significant incidence of adhesion formation.

Animals↗
PubMed1994

Arthroscopic repair of combined Bankart and superior labral detachment anterior and posterior lesions: technique and preliminary results.

Over a 3-year period nine of 585 patients undergoing shoulder surgery were found to have a superior labral detachment anterior and posterior (SLAP) lesion. Seven patients also had an associated Bankart lesion and underwent arthroscopic repair of the entire anterior-inferior-superior-posterior labral detachment using the Suretac (Acufex Microsurgical Inc., Mansfield, MA) fixation device. The technique used requires an accessory anterior-lateral portal to access the superior-posterior labral detachment and an accessory anterior-inferior portal to access the Bankart lesion. Three to four Suretacs were required for repair in these cases. At an average follow-up of 19 months (range 15-22), five of seven patients had no pain, full range of motion, and a full premorbid activity level. One patient redislocated at 4 months postoperatively and was successfully managed with an open repair, and one patient developed a stiff shoulder that was successfully managed with arthroscopic release and manipulation. We conclude that this arthroscopic technique is a useful method to manage extensive labral detachment in selected patients.

Adolescent↗
PubMed1994

Basilar invagination and mid-line skeletal abnormalities due to in utero exposure to phenytoin.

A case of basilar invagination which is thought to have arisen from the patient's intrauterine exposure to phenytoin is presented. The patient was treated surgically by foramen magnum decompression and occipito-cervical fusion, and by transoral resection of the clivus. His symptoms of brain stem compression were alleviated and the role of phenytoin in the production of his craniocervical abnormality is discussed.

Adult↗
PubMed1994

Myocardial vagal stimulation impairs lower esophageal sphincter function.

BACKGROUND: Coronary artery disease and gastroesophageal reflux disease frequently coexist, but a direct pathophysiologic link has not been established. METHODS: This study examines the effect of myocardial vagal receptor stimulation on lower esophageal sphincter (LES) tone in eight adult mongrel dogs, each acting as its own control. Pharmacologic stimulation was carried out by the application of 1 cm gauze patches soaked in nicotine (200 micrograms/ml) to the epicardium. Epicardial vagal receptors were stimulated mechanically by digital friction. RESULTS: Pharmacologic stimulation produced a rapid fall in LES tone from a mean (SEM) of 12.6 (1.5) to 8.6 (0.9) sphinctometer units (p = 0.007). Mechanical stimulation also produced a rapid fall from 12.0 (1.5) sphinctometer units to 6.8 (0.7) (p = 0.007). Both were associated with a drop in mean arterial blood pressure and heart rate. Sham patches soaked in sterile water produced no effects. CONCLUSIONS: These data suggest a direct vagal reflex linking the myocardium and the LES that may explain the high incidence of gastroesophageal reflux in patients with heart disease.

Animals↗
PubMed1993

Endothelium derived relaxing factor is absent in experimental in situ vein grafts.

Endothelium derived relaxing factor (EDRF) is a local modulator of vasomotor tone in most blood vessels. Reversed vein grafts in several animal models do not produce EDRF when stimulated, and have been shown to have altered responses to several vasoconstrictors. The preservation of EDRF production and vasomotor function in in situ vein grafts was examined in this study. In situ vein grafts of the right carotid artery were performed in five mongrel dogs using external jugular vein. The contralateral jugular vein was used as a control. The vessels were harvested after 6 weeks and rings from the central portion of each vessel studied in vitro in an organ bath. Following cumulative dose response curves to noradrenaline, the rings were precontracted with the estimated ED50 (50% effective dose) dose of noradrenaline, and cumulative doses of acetylcholine added to induce EDRF release. The vein grafts were hypersensitive to noradrenaline, the ED50 being reduced from 8.7 +/- 2.7 x 10(-7) M in the jugular veins to 1.7 +/- 0.7 x 10(-7) M in the vein grafts (p < 0.05). All of the jugular vein segments relaxed in response to acetylcholine with a mean maximal relaxation of 42 +/- 6% of precontraction. None of the vein graft segments relaxed in response to acetylcholine despite the presence of an intact endothelium on scanning electron microscopy, but did relax in response to calcium ionophore. The results indicate that in situ vein grafts, like reversed grafts, fail to produce EDRF in response to acetylcholine. The grafts are also hypersensitive to noradrenaline.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

A community nursery nurse working with families with multiple births.

The introduction of skill mix into the health visiting services is causing debate and some concern among health visitors. Patricia Marks describes a three year project in Brighton health authority in which a community nursery nurse was introduced to work in the home with families with multiple births. The role of the community nursery nurse is different from that of the health visitor but this extra input to these families has relieved pressure on health visitors' time, as well as being of tremendous help to the families.

Community Health Nursing↗
PubMed1992

An evaluation of the antihistamine activity of acrivastine and its onset in human skin.

In a double-blind, two-period crossover study, 24 healthy volunteers were evaluated to establish the time of onset of action of activity of acrivastine in suppressing the weal and flare response to intradermally injected histamine. Volunteers received single doses of 8 mg acrivastine and placebo according to a fully randomized, balanced treatment plan. Acrivastine significantly (P less than 0.002) reduced the flare response induced by 0.4 micrograms histamine challenge 15 min after oral acrivastine dosing when compared with placebo. A significant (P less than 0.001) reduction of the weal response was noted at 25 min, although trends in this direction were already present at earlier time points.

Administration, Oral↗
PubMed1991

Cystic duct obliteration and gallbladder mucosal destruction: a feasible alternative to cholecystectomy.

'Chemical cholecystectomy' has been proposed as an alternative to removal of the gallbladder. This study assessed cystic duct obliteration using bipolar electrocoagulation (with sham cannulation controls) and gallbladder mucosal treatment with tetracycline (or saline controls) in 29 mongrel dogs. Cystic duct obstruction was assessed by tube cholecystography at day 14, and epithelial damage by histology at day 42. Electrocoagulation by duct diathermy effectively occluded the cystic duct in 14 of 19 animals; however, this was associated with mucocele formation unless mucosal treatment with tetracycline was also performed. Immediate instillation of tetracycline after duct electrocoagulation produced only partial epithelial damage. The combination of duct electrocoagulation and delayed tetracycline instillation at 14 days produced complete destruction of all gallbladder epithelium and an effective chemical cholecystectomy.

Animals↗
PubMed1991

Imaging techniques of the shoulder: present perspectives.

Through its ability to evaluate the individual components of the rotator cuff, the labral-capsular complex, the subacromial and subdeltoid spaces, and the glenoid, humerus, clavicle, and acromion, MRI provides a means of comprehensively evaluating the shoulder. Further advances in the use of intra-articular MRI contrast agents will undoubtedly enhance the role of MRI in the evaluation of subtle labralcapsular pathology. Although they are experimental, kinematic studies of the shoulder may provide valuable insight into the pathogenesis of disorders such as impingement syndrome. The ability of MRI to provide detailed pathologic information about individual components of the shoulder, particularly the rotator cuff, presents a challenge to shoulder surgeons. Patient symptomatology should be correlated with MRI findings and the clinical significance attached to different pathologies reevaluated. Through rigorous confirmation of MRI findings, dedicated therapeutic algorithms can be established based on detailed clinicopathologic data. Present and future surgical and nonsurgical management of the shoulder will undoubtedly be shaped by MRI.

Athletic Injuries↗
PubMed1990

Overexpression of HER-2/neu is associated with poor survival in advanced epithelial ovarian cancer.

Previous studies have suggested that overexpression of HER-2/neu oncogene occurs in 15-40% of breast cancers and that overexpression is associated with poor prognosis. In the present report, we have used an immunohistochemical technique involving a monoclonal antibody specifically reactive with the external domain of HER-2/neu to study expression of HER-2/neu in frozen sections of normal ovary and advanced epithelial ovarian cancer. The intensity of staining for HER-2neu was always moderate or less (0-2+) in normal ovarian epithelium. Among 73 ovarian cancers, 50 (68%) had staining similar to that for normal ovarian epithelium (0-2+) while 23 (32%) stained heavily (3+). Survival of the 23 patients with high HER-2/neu expression (median, 15.7 months) was significantly worse (P = 0.001) than that of the 50 patients (median, 32.8 months) with normal HER-2/neu expression. In addition, patients whose tumors had high HER-2/neu expression were significantly less likely to have a complete response to primary therapy (P less than 0.05) or have a negative second-look laparotomy when serum CA 125 levels were normal preoperatively (P less than 0.05). These findings suggest that HER-2/neu deserves further evaluation as a prognostic marker in epithelial ovarian cancer.

Female↗
PubMed1990

A critical analysis of Swanson ulnar head replacement arthroplasty: rheumatoid versus nonrheumatoid.

Clinical and radiographic assessment of the results of 40 Swanson silicone ulnar head prosthesis implants in three different patient groups is presented. Twenty-eight were done for treatment of rheumatoid arthritis, eight for ulnoradial impingement after the Darrach procedure, and four for ulnocarpal impingement resulting from malunited Colles' fractures. Patients were reviewed 12 to 48 months after operation (mean, 29 months). Seventy-eight percent of patients reported relief of pain and improved function. Radiologic examination showed that all patients exhibited resorption of the distal ulna (mean 4.4 mm) and that resorption was worst in the group with rheumatoid arthritis. Bone resorption about the implant predisposed the cap to both side-to-side tilt and pistoning of the prosthesis on supination and pronation. There was a 10% revision rate because of silicone synovitis. Although clinical results remain satisfactory for patients with rheumatoid arthritis and ulnocarpal impingement, the radiologic results suggest that Swanson ulnar head replacement should be restricted to elderly patients with rheumatoid arthritis.

Age Factors↗
PubMed1990

Results of a locking-hook spinal rod for fractures of the thoracic and lumbar spine.

The results of a consecutive series of 110 patients treated with the locking-hook spinal rod are presented. A prospective protocol was completed in 95 patients. Pain was absent or mild in 93%. In those patients with a partial neurologic deficit, there was recovery of at least one Frankel grade in 84%. The overall kyphotic deformity was reduced from 21 to 17 degrees. In those patients in whom no anterior surgery was performed, the deformity improved from 21 to 13 degrees. No rod fractures occurred, and the overall instrument complication rate was 13.7%, of which one was due to infection and four secondary to uncrimped nuts, for a true complication rate of 8.4%. The locking-hook spinal rod has proven to be a satisfactory internal fixation device in the treatment of unstable thoracolumbar fractures.

Adult↗