Opioid-mediated changes in nociceptive threshold during pregnancy and parturition in the sow

This study aimed to investigate if pregnancy-induced hypoalgesia occurs in the sow, and to examine the role of endogenous opioids which are known to be released in response to nociception. Sixteen Large White x Landrace multiparous sows were tested in straw bedded pens (2.5 x 2.5 m) during weeks 4, 8 and 12 of pregnancy and over the farrowing period. Testing involved thermal stimulation of eight areas on the rear-quarters of the sows with a CO2 infra-red laser until a physical response was seen (tail flick, leg move or muscle twitch) or for a maximum of 16 s. Over the farrowing period testing was more frequent, and at 3.75 h after the birth of the first piglet, half the sows received an injection (i.m.) of an opioid antagonist naloxone (N) (1 mg kg(-1) body weight) with the remainder receiving a control dose of saline (S). Responses were recorded 15 and 30 min post-injection. There was no significant difference between response times over weeks 4, 8 and 12 of pregnancy (P = 0.152), however a significant rise was seen from week 12 to 5 days before parturition (P = 0.002). Response times continued to rise until the birth of the first piglet by which time the majority of sows had stopped responding within 16 s (P < 0.001). Response times fell over days 1, 2 and 7 post-partum. After administration of naloxone response times fell compared to control animals at 15 min (P < 0.001) and 30 min (P < 0.01) post-injection. These results suggest that nociceptive threshold increases during late pregnancy in the sow, perhaps as an endogenous defence against labour pain, and that during parturition this change in nociceptive threshold is, at least in part, opioid-mediated. Oxytocin is known to be inhibited by endogenous opioids at parturition, thus future research should consider the potential role of increased nociception at birth as a negative feedback to oxytocin release.

Xamoterol improves the control of chronic atrial fibrillation in elderly patients

Twenty digitalized elderly patients with chronic atrial fibrillation were randomized into a double-blind cross-over study. None was in overt heart failure and all were taking < 80 mg frusemide daily. They received xamoterol 200 mg b.d. for 2 months with their usual dose of digoxin for 1 month and placebo digoxin for the other month. Twenty-four-hour heart rate analysis was done at baseline and at the end of each treatment period. Compared with baseline digoxin, xamoterol alone significantly increased nocturnal minimum heart rate [85 +/- 17 vs. 62 +/- 9 (mean +/- SD), p < 0.0001] without affecting daytime maximum heart rate (132 +/- 18 vs. 122 +/- 20, p = NS). Compared with baseline digoxin, xamoterol plus digoxin significantly increased nocturnal minimum heart rate (68 +/- 8, p < 0.05) and reduced daytime heart rate (114 +/- 17, p < 0.05). The mean number of pauses > 1.5 s was significantly reduced by xamoterol alone. Walking distance in 6 minutes was 406.1 +/- 27.1 m (mean +/- SE) at baseline and improved significantly on both treatments (450.3 +/- 19.8 on xamoterol; p < 0.02 and 453.7 +/- 19.2 on xamoterol plus digoxin; p < 0.01). No significant change was found in subjective measurements of palpitations, breathlessness and well-being using visual analogue scales. Xamoterol combined with digoxin improves effort tolerance and heart-rate control by reducing diurnal tachycardia and nocturnal bradycardia and pauses.

Age-associated alterations in thirst and arginine vasopressin in response to a water or sodium load

We have examined simultaneous changes in thirst, plasma osmolality and arginine vasopressin, after oral water loading or hypertonic saline infusion. The studies were carried out in the same subjects, comprising young controls aged 26.8 years (SD 4.8, n = 10) and health status-defined elderly people aged 72.1 years (SD 3.1, n = 10). Water loading caused significant falls in plasma osmolality (p < 0.001) and thirst (p < 0.001), but there was no variation with age. Infusion with 462 mmol/l of sodium chloride increased plasma osmolality significantly (p < 0.001), but there was no variation with age (p = 0.12). The perception of thirst during the osmotic loading experiment was recorded differently by the two age groups (p < 0.0001). However, linear regression analysis showed no age difference in the relationship between thirst and plasma osmolality during osmotic loading. During osmotic loading the relationship between the plasma concentration of arginine vasopressin in response to increasing plasma osmolality varied significantly (slope: p = 0.02; intercept: p = 0.02). Plasma arginine vasopressin rose more rapidly with increasing plasma osmolality in old subjects.

Combination diuretic treatment in severe heart failure: a randomised controlled trial

OBJECTIVES

(a) To test the hypothesis that a fixed 3 day course of the combination of a thiazide and loop diuretic is as effective as more prolonged treatment in the management of severe resistant cardiac failure. (b) To compare two thiazide diuretics (bendrofluazide and metolazone) in combination with loop diuretics in the treatment of severe resistant cardiac failure.

DESIGN

Randomised study with a 2 x 2 factorial design.

SETTING

Provincial teaching hospital.

PATIENTS

33 consecutive patients (40 episodes) admitted with severe congestive cardiac failure (New York Heart Association class III or IV) unresponsive to intravenous loop diuretics for 48 hours.

MAIN OUTCOME MEASURES

Change in daily weight and serum electrolytes and clinical improvement in heart failure.

RESULTS

Diuresis was established during 37 of 40 episodes; of the rest two patients died in hospital. On 36 occasions improvement was sufficient to allow discharge from hospital. Median (range) maximal weight loss was -5.05 (-11.3 to 1.6) kg after the addition of bendrofluazide and -5.6 (-12.2 to 4.8) kg after the addition of metolazone (NS). Area under the body weight loss against time curves showed no significant difference between the two thiazide diuretics. Median (range) maximal weight loss after three days of treatment was -5.4 (-12.2 to 4.8) kg and -5.5 (-10.3 to 1) kg after a more prolonged course of median (range) 5.6 (1 to 13) days (NS). Area under the body weight loss time curves showed no significant difference between the two durations of treatment. Bendrofluazide was associated with fewer electrolyte disturbances.

CONCLUSIONS

Bendrofluazide and metolazone were equally effective in establishing a diuresis in patients with severe congestive cardiac failure resistant to loop diuretics. A fixed three day course of the combination was as effective as a longer course.

Integration between general and geriatric medicine: a needs related policy

A joint admitting policy between a general physician and a physician in medicine for the elderly reduced the length of stay in acute medical beds by 25% without increasing the length of stay in rehabilitation beds. The basis for the cooperation was not related to age but rather to the perceived needs of the patient on admission. This method of integration between medicine and geriatrics could be implemented in most hospitals.

Myopathy in HIV infection: the role of zidovudine and the significance of tubuloreticular inclusions

Muscle biopsies were obtained from 33 consecutive HIV-infected patients with symptoms suggestive of muscle disorder. Twenty-three patients had clinical evidence of myopathy; 18 of these had been taking zidovudine (AZT) for between 8 and 28 months, and were found to have a multifocal necrotizing myopathy with little or no inflammation. However, the remaining five clinically myopathic patients, who had never received AZT or had stopped treatment at least 5 months earlier, had either a necrotizing myopathy which appeared indistinguishable for that seen in patients taking the drug, or an inflammatory myopathy. The 10 clinically non-myopathic patients showed no significant histological abnormalities. Tubuloreticular inclusions (TRI), in capillary endothelial cells, were found in all clinically myopathic cases but were not seen in five out of ten clinically non-myopathic cases. We suggest that AZT causes a myopathy only when an underlying HIV-related inflammatory myopathy is present. The drug appears to substantially reduce the inflammatory reaction in the muscle, but this may recur when the drug is stopped. The appearance of TRI may be the first manifestation of HIV activity in muscle.

Subcutaneous versus intravenous administration of heparin in the treatment of deep vein thrombosis; which do patients prefer? A randomized cross-over study

Patient preference for intravenous or subcutaneous heparin in the treatment of deep venous thrombosis was assessed in a randomized cross-over study. Twenty patients with venographically proven deep venous thrombosis were randomized to receive subcutaneous or intravenous heparin for 3 days followed by 3 days of the other treatment. Discomfort at the injection site, assessed by visual analogue scale, was significantly less for the subcutaneous than the intravenous administration route (P < 0.001), mobility was thought to be better when receiving subcutaneous heparin (P < 0.005) and patients' overall preference was for subcutaneous treatment (P < 0.001).

Water homeostasis and ageing

The elderly are at risk of developing disturbances of water homeostasis, and clinicians have to rely on laboratory measurement to determine their presence and magnitude. Optimum management depends on having a clear understanding of age-associated changes in water homeostasis. Many studies have flawed methodology, but some conclusions can be drawn. There is a diminished thirst, but the relationship of plasma osmolality to arginine vasopressin is at least preserved, and may show increased responsiveness. There is reduced renal function with age and the kidneys' ability to produce a concentrated urine declines. Similarly, the excretion of a water load becomes impaired. Further study is needed of the interaction of specific diseases with these age-associated changes.

Influence of age on plasma osmolality: a community study

We have shown an age-associated increase in plasma osmolality (p less than 0.001) in 152 randomly selected subjects, living in the community. In the old [mean age 78.0 (7.5) years] the plasma osmolality was 302.2 (300.6-303.8) mOsmol/kg compared with 291.2 (290.0-292.3) mOsmol/kg in the young [39.2 (11.2) years] (p less than 0.0001). In a further group of 20 screened, health status defined, elderly subjects the plasma osmolality was 298.1 (295.9-300.3) mOsmol/kg, which was significantly higher than the young group (p less than 0.0001) but lower than the unscreened old subjects (p = 0.005). The variance was also significantly lower (p = 0.03). The results may reflect a loosening of homoeostatic control and highlight the need for care in subject selection in studies of ageing.

A simple and rapid method for detecting human immunodeficiency virus by PCR

A simple, sensitive and specific method using the polymerase chain reaction (PCR) for amplification of human immunodeficiency virus type 1 (HIV-1) is described. The method involves minimal manipulations. Peripheral blood mononuclear cells (PBMC) were prepared by a rapid Ficoll-Paque gradient method. Lymphocytes were lysed in PCR buffer containing Proteinase K and detergents, and subjected to amplification under stringent conditions, using two primer pairs. Amplified DNA sequences were hybridized with a 3'-end labelled probe, electrophoresed on agarose gels and visualised by ethidium bromide staining. Identification of amplified HIV-1 proviral DNA sequences was confirmed by autoradiography. HIV-1 sequences were amplified in all samples from 103 HIV-1 seropositive individuals, but not in 40 HIV-1 seronegative controls. The absence of contamination may be attributable in part to minimisation of manipulations before amplification.

Acute rheumatic fever in human immunodeficiency virus infection

A 25-year-old homosexual man with a childhood history of rheumatic heart disease presented with painful joints, fever and chest pain. He was diagnosed as having acute rheumatic fever and was found to be HIV antibody-positive. His illness responded to conventional treatment but he had a persistently low CD4 lymphocyte count and was started on zidovudine. Interpretation of the significance of a low CD4 lymphocyte count is problematic in a patient with coincident rheumatic fever and HIV infection as both conditions can cause CD4 lymphopenia.

Preliminary report: accurate assays for anti-HIV in urine

Untreated urine specimens from 358 patients (344 attending genito-urinary medicine clinics, 14 haemophiliacs) and 353 blood donors were tested blind by a simple IgG-capture particle-adherence test (GACPAT) and a rapid IgG-capture enzyme-linked immunosorbent assay (GACELISA) for antibody to human immunodeficiency virus (anti-HIV). All 158 urine specimens from seropositive subjects were anti-HIV positive by GACPAT and 157 of them (99.4%) were positive by GACELISA. Tests on 553 urine specimens from seronegative subjects gave two repeatable false-positive reactions by GACPAT (0.4%) and none by GACELISA. By means of a modified procedure anti-gp160 was detected by commercial western blot in the urine of 44 of 45 seropositive subjects examined. IgG-capture assays will detect anti-HIV in unconcentrated urine and so allow a diagnosis in circumstances when blood sampling is impracticable.

Cultivation of human immunodeficiency virus from whole blood: effect of anticoagulant and inoculum size on virus growth

Human immunodeficiency virus (HIV) was cultivated directly from whole blood treated with anticoagulant by cocultivation with phytohaemagglutinin-stimulated cord blood lymphocytes. When heparin was used as the anticoagulant, isolation rates were low (10% to 56%, depending on the patient group); but when EDTA was used, isolation rates were much higher (50% to 100%). Culture of whole blood gave results identical to those of culture of separated peripheral mononuclear cells, and in some cases virus could be isolated from as little as 10 microliters of unseparated EDTA anticoagulated blood.