An animal model of the relationship between systemic hypertension and repetitive episodic hypoxia as seen in sleep apnoea

SUMMARY  Multiple factors may be responsible for acute and chronic blood pressure changes during obstructive sleep apnoea. A popular hypothesis is that recurrent episodic hypoxia stimulates chemoreceptors which, in turn, cause sympathetically mediated vasoconstriction and perhaps long-term vascular remodelling. Disruption of sleep architecture secondary to frequent arousals may also cause chronic stress which may contribute to diurnal hypertension. A less likely factor elevating blood pressure is the effect of abrupt intra-thoracic pressure changes on venous return and cardiac output. The rat responds to chronic, recurrent episodic hypocapnic hypoxia (12-s bursts of nitrogen followed by air into Plexiglas chambers, every 30 s, 7h d^-1, 2–4% nadir ambient oxygen) with sustained increase in diurnal blood pressure (10–14 mmHg). Subsequent studies reveal that carotid sinus nerve section (chemodener-vation) and chemically induced peripheral sympathetic denervation with the neurotoxin 6-OH dopamine both eliminate this blood pressure-elevating effect of chronic episodic hypoxaemia. Using this model, Sprague-Dawley rats have been challenged with both eucapnic hypoxia and asphyxia and failed to show an additional blood pressure elevation above that caused by hypoxia (hypocapnic) alone. It appears that hypocapnic hypoxia creates a maximal stimulus to the sympathetic nervous system to which the addition of hypercarbia does not increase the blood pressure response. An alternative explanation is that the rat has protective mechanisms that limit the diurnal blood pressure response from further increase.     

Serum hyaluronic acid level as a predictor of disease progression in osteoarthritis of the knee

Objective. To investigate the prognostic value of serum hyaluronic acid (HA) and keratan sulfate (KS) levels in relation to tibiofemoral osteoarthritis (OA) of the knee. Methods. Clinical and demographic data were collected on 94 patients. Radiographs were obtained at study entry and at 5-year followup. Disease progression was defined as 2 mm of joint space narrowing of any tibiofemoral compartment, and/or knee joint surgery during the study period. Serum HA and KS were measured and levels were correlated with entry data and disease progression. Results. At entry, HA levels were significantly related to disease duration (P = 0.036), minimum joint space (P = 0.049), and previous surgery (P = 0.001). After these variables were taken into account, patients whose disease had progressed were shown to have had significantly higher levels of HA at baseline compared with those whose disease had not progressed (P = 0.019). However, there were no significant differences in levels of serum KS between those with and those without disease progression, at entry (P = 0.779) or at subsequent visits. Conclusion. These results suggest that serum HA levels predict disease outcome in OA of the knee and confirm that a single measurement of the serum level of KS is not useful as a prognostic marker in OA.     

ESTIMATING POPULATION SIZE WHEN DUPLICATES ARE PRESENT

Each of K mental health programmes reports the number of patients served in a year. The sum of these numbers, y, is an overcount because some patients are seen in more than one programme. Health care planners need to know the unduplicated number served by the mental health system. Thus, there is an unknown number, M, of distinct individuals who appear on one or more of K lists; some appear on multiple lists and the duplicates are not readily identifiable. Let X be the number of lists on which a randomly selected individual appears. When E(X) is known, y/E(X) is the natural estimator of M. We assume that we know the number of programmes, X_i, used by the ith individual in a random sample of recipients of service. Here, the intuitive estimator, Y/X¯ has desirable statistical properties. We give confidence interval estimators for M. We apply the method to estimate the number of individuals served in 1991 by the mental health programmes in New York State.     

DOCTORS AND NURSES: REFERRALS BY GENERAL PRACTITIONERS TO DIFFERENT ARMS OF AN OLD AGE PSYCHIATRY SERVICE

General practitioners’ referrals to the medical and nursing arms of an old age psychiatry service over a 6-month period were examined retrospectively. Doctors were referred patients with a past psychiatric history who had been known to the service, did not live alone and in whom first-line treatments had failed. The nursing team were asked to carry out specific therapies by the GPs. There were no differences in support, diagnosis or medication between the groups. The need for multidisciplinary input to all referrals to services is stressed.     

Permanent Pacemaker Placement in Chronic Atrial Fibrillation Associated with Intermittent AV Block and Cerebral Symptoms

We examined the hypothesis that a greater than or equal to 2 second pause detected on 24-hour Holter monitoring in patients with persistent atrial fibrillation and complaints of syncope or dizziness lacked sufficient specificity to warrant implantation of a permanent pacemaker. We retrospectively reviewed cases from our 24-hour electrocardiographic (Holter) monitoring data base. A total of 411 consecutive Holter monitoring records demonstrating persistent atrial fibrillation obtained during a 5-year period (1982 to 1987) were examined. One hundred and five (26%) patients had cerebral symptoms (dizziness or syncope) as a primary indication for monitoring 80 (76%) patients were identified with documented ventricular pauses of greater than or equal to 2 seconds. Three hundred and six patients (74%) underwent 24-hour monitoring without cerebral symptoms as an indication and 209 (68%) patients had greater than or equal to 2-second pauses. Clinical information was available in 164 (50 symptomatic and 114 asymptomatic) patients. There were no significant differences in the clinical or Holter findings between the two groups. Of the 50 symptomatic patients, 15 (30%) underwent permanent pacemaker placement and the remaining 35 (70%) were managed conservatively during a mean follow-up of 23 +/- 5 months. Eleven of 15 paced (73%) and 31 of 35 (89%) nonpaced patients experienced resolution of their cerebral symptoms (NS). The sensitivity of Holter monitoring in detecting pauses of greater than or equal to 2 seconds in patients with cerebral symptoms was high (76%), but the specificity (32%) and positive predictive values (28%) were low.(ABSTRACT TRUNCATED AT 250 WORDS)     

SURGERY FOR CONGENITAL ESOTROPIA

Esotropia in the neonatal period is significant if it is prolonged or recurrent, while exotropia is not. Straight eyes for most of the waking hours is the rule rather than the exception in the newborn. Successful surgical management of congenital esotropia depends on equal attention to diagnosis, planning and treatment These are preceded by proper timing of the surgical procedure and followed by careful, comprehensive attention to the needs of the patient. The manifest cosmetic and hoped-for functional benefit of early surgery, when supported by competent paediatric anaesthesia, makes early surgery the logical choice for treatment of congenital esotropia.     

TISSUE ADHESIVE THERAPY FOR CORNEAL PERFORATIONS

The current indications for and method of application of tissue adhesive are described. A method for an expanded utilisation of tissue adhesive is discussed. To study the effect of the introduction of tissue adhesive to The Wilmer Institute in 1974, the records of 104 consecutive non-traumatic corneal perforations or descemetoceles admitted to The Wilmer Institute from 1960 to 1980 were assessed retrospectively with follow-up being obtained from records or from referral physicians for 87 of these perforations. Forty-nine percent of the cases were caused by bacterial corneal ulcers, 13% by exposure, 12% by chemical burns, 6% by fungal keratitis, 5% by herpes simplex keratitis, and 15% were undiagnosed. Since the introduction of tissue adhesive in 1974, there has been an apparent trend towards a lower enucleation rate (6%) in the tissue adhesive treated group compared with 19% in perforations treated by other therapies.     

Watery Diarrhea Syndrome with Elevated Levels of Vasoactive Intestinal Polypeptide Associated with Pancreatitis and Pancreatic Pseudocyst

A 32-year old patient presented with recurrent pancreatitis, severe watery diarrhea and elevated serum levels of vasoactive intestinal polypeptide. His diarrhea appeared to respond to intramuscular propantheline. Initially he improved but had another attack of pancreatitis while hospitalized. Evaluation by ultrasound revealed the presence of a pseudocyst and endoscopic retrograde pancreatography demonstrated complete occlusion of the main pancreatic duct. Exploratory laparotomy was performed with drainage of a pseudocyst. Analysis of the pseudocyst fluid revealed an elevated amylase, lipase and vasoactive intestinal polypeptide level. It is belived that this patients's severe diarrhea was related to his pancreatitis and pancreatic pseudocyst with elevated levels of vasoactive intestinal polypeptide.