Dihydrocodeine for breathlessness in "pink puffers"

Eighteen patients with severe breathlessness due to chronic airflow obstruction completed a randomised placebo controlled double blind cross over trial of the effect of dihydrocodeine 15 mg on breathlessness, disability, and exercise tolerance. There were three periods of one week each. During the first two weeks patients were instructed to take dihydrocodeine 15 mg or placebo 30 minutes before exercise as required up to three times daily. During the third week patients received either dihydrocodeine or placebo on alternate days. During the weekly dihydrocodeine period patients were more mobile (pedometer distance increased by 16.8%) and less breathless (daily visual analogue score of breathlessness reduced by 17.8%). This benefit was confirmed by treadmill testing at the end of each treatment period, when maximum distance walked was 16.5% higher and breathlessness 11.8% less after dihydrocodeine compared with placebo. Similar benefit in breathlessness occurred during alternate day treatment. No adverse effects were encountered. Dihydrocodeine 15 mg 30 minutes before exercise offers appreciable benefit to patients with severe breathlessness due to chronic airflow obstruction.

Are "pink puffers" more breathless than "blue bloaters"?

Breathlessness, disability, and exercise tolerance were assessed in 26 patients with severe chronic airflow limitation (forced expiratory volume in one second (FEV1) less than or equal to 1 litre) divided into two groups--15 patients who were normocapnic (pressure of arterial carbon dioxide (Paco2) less than 5.5 kPa (less than 41.4 mm Hg)), and 11 patients who were hypercapnic (Paco2 greater than 6 kPa (greater than than 45.1 mm Hg)). The two groups were well matched for spirometric values (FEV1 0.59 1 and 0.62 1, respectively). All of the hypercapnic patients could improve blood gas tensions towards normal by hyperventilation. There were no significant differences in visual analogue scores of breathlessness during treadmill exercise, disability (oxygen-cost diagram, dyspnoea grade), or exercise tolerance (six-minute walk, maximal consumption of oxygen during bicycle ergometry, distance walked to exhaustion in progressive treadmill test). The findings show that the "fight" to maintain normal blood gas tensions in the face of severe airflow limitation does not have an appreciable cost in terms of disability.

Changes in histochemical profile of rat respiratory muscles in hypo- and hyperthyroidism

Rat respiratory muscles underwent considerable changes in histochemical fibre type profile in response to hypo- and hyperthyroidism. Hypothyroidism increased the proportion of type 1 slow oxidative fibres in diaphragm and to a lesser extent in intercostal muscles. Hyperthyroidism resulted in a decreased proportion of type 1 fibres in both diaphragm and intercostals. These changes were broadly comparable to those reported previously in rat limb muscles. In normal rat respiratory muscles, the type 1 fibres were characterized by very high levels of beta-hydroxybutyrate dehydrogenase which was thought to contribute to the fatigue-resistance of these muscles. The type 2B fast glycolytic fibres, and to a lesser extent type 2A fast oxidative fibres, contained high levels of mitochondrial alpha-glycerophosphate dehydrogenase, an enzyme known to be specifically affected in dysthyroid states. The implications of the observed changes in fibre type profile with respect to the oxidative metabolism of rat respiratory muscles are discussed.

Leukotriene C4 and dimethylphenylpiperazinium-induced responses in canine airway tracheal muscle contraction and fluid secretion

Leukotrienes have been implicated as putative mediators in several air way diseases. In previous canine studies it was shown that leukotriene C4 (LTC4) enhanced fluid secretion over baseline values and this enhancement could be blocked by hexamethonium. This indicates that leukotrienes have as one of their actions, stimulation of ganglionic motor neurons. In the present study, we determined that LTC4 acts at a similar site as the specific nicotinic receptor agonist dimethylphenylpiperazinium (DMPP). Both LTC4 and DMPP when given alone enhanced mucus secretion and induced tracheal muscle contraction over control baseline (p less than 0.05). When added to DMPP, LTC4 enhanced the DMPP effect of muscle contraction at 5 and 8 micrograms by a synergistic amount, while the secretion was only additive. The slopes of the dose-response curves for DMPP + LTC4 did not differ by a statistically significant amount. LTC4 and DMPP act on a similar, if not the same, ganglionic receptor.

Effect of an anteroventral third ventricle lesion on NaCl hypertension in Dahl salt-sensitive rats

An anteroventral third ventricle (AV3V) lesion in the brain prevents several forms of experimental hypertension. The present experiment was designed to determine whether the AV3V lesion prevents NaCl-induced hypertension in Dahl salt-sensitive (S) rats and whether attenuation of vasopressin release reported in lesioned rats contributes to the protective effect of the AV3V lesion against hypertension. After the AV3V lesion Dahl S rats received daily injections of either vasopressin (pitressin tannate, 500 mU/kg) or vehicle during 10 wk of 8% high-NaCl diet. Sham-lesioned rats served as controls. The blood pressure in sham-lesioned rats receiving vehicle was 189 mmHg after 10 wk of high-NaCl diet. Lesioned rats given vehicle showed a significantly smaller increase in blood pressure than sham-lesioned rats (P less than 0.001), the blood pressure averaging 161 mmHg at 10 wk. Lesioned rats given vasopressin also showed a smaller increase in blood pressure than sham-lesioned rats (P less than 0.05), but the final blood pressure averaged 176 mmHg and was significantly higher than that of lesioned rats given vehicle (P less than 0.025). Vasopressin injections corrected the hypernatremia in lesioned rats. In another experiment the effect of the AV3V lesion on the renal papillary plasma flow (RPPF) in Dahl S rats was studied. Dahl S rats have a lower RPPF than Dahl salt-resistant (R) rats even on a low-NaCl intake. The AV3V lesion increased the RPPF by 14% in S rats (P less than 0.025). These findings suggest that NaCl-induced hypertension in Dahl S rats requires the integrity of the AV3V region for its full expression, and the ability of the AV3V lesion to attenuate the NaCl-induced hypertension in Dahl S rats is partly related to the attenuation of vasopressin release. Moreover, the AV3V lesion partly corrected one of the characteristic features of Dahl S rats, the reduction in RPPF, when compared with Dahl R rats, with both strains on a low-NaCl intake.

Solubilization and initial biochemical characterization of an IgE-destroying enzyme on rat peritoneal mast cells

Previous studies had demonstrated that incubation of IgE with purified rat mast cells can result in the time and cell concentration-dependent destruction of the ability of the IgE to be bound to specific receptors on rat basophil leukemia cells. The IgE-destroying activity, which has an extremely acid pH optimum, resisted attempts at solubilization using detergents. However, it was solubilized in good yield by use of chaotropic salts and especially KOCN. The soluble activity is stable to freezing and thawing, and to heating to 68 degrees C for 60 min. It is promptly destroyed upon boiling. IgE destruction was linear with time up to 20 min and a series of products, mol. wts 138,000, 92,500, 60,000 and 36,500, are formed during the reaction. No pH optimum for the reaction could be found because, as the pH was lowered below 4.0, the spontaneous destruction of IgE became too great. At pH 4.75 the apparent Km for the reaction was 0.55 microM and Vmax was 0.4 nmoles IgE/10(4) mast cell equivalents/min. IgE-destroying activity could be inhibited by heat-inactivated serum, and by relatively high concentrations of crude alpha 1-antitrypsin, aprotinin, lima bean and soybean trypsin inhibitors and by p-nitroguanidinobenzoate. A large number of other protease inhibitors were inactive.

The photomyoclonic reflex: an artefact in the clinical electroretinogram

An artefact may appear in the clinical electroretinogram (ERG) that can interfere with the recording and interpretation of the ERG b wave. This artefact, the photomyoclonic reflex (PMR), was studied by covering the eye containing the recording electrode and stimulating the fellow eye. Records obtained by this technique before and after administration of a modified Van Lint lid block demonstrated that most of the PMR is due to a reflex contraction of the orbicularis muscle. The remaining part of the PMR was ascertained by eye movement recordings to be a 1.5 degrees to 3.5 degrees downward and medial eye movement. In most persons the PMR occurs with a latency that is fast enough (59 ms +2- 7 ms) to interfere with interpretation of the b wave under most conditions. The PMR can be minimised in some cases by habituation or conditioned suppression. However, these methods generally do not extinguish the PMR but reduce it enough so that it would not readily be rejected as artefact. In such cases the PMR may produce a wave form that mimics a normal amplitude ERG but with delayed implicit time.

Thromboxane, prostaglandin I2 (epoprostenol), and the hemodynamic changes in equine endotoxin shock

This study had 2 objectives: (i) to correlate plasma thromboxane and prostaglandin I2 (epoprostenol) concentrations with hemodynamic changes occurring in equine endotoxin shock, and (ii) to determine the effects of flunixin meglumine on plasma concentrations of these prostaglandins relative to hemodynamic changes. Shock was induced in 2 groups, each of 4 anesthetized ponies, and in a 3rd group of 2 ponies. Group A ponies were given endotoxin only (and were not treated), and group B ponies were given endotoxin and then treated with flunixin meglumine. Group C ponies were treated with flunixin meglumine 5 minutes before they were fiven endotoxin. Arterial, pulmonary arterial, and central venous pressures were measured and blood samples were collected at 0, 0.1, 0.25, 0.5, 1, 1, 3, and 4 hours after ponies were given the endotoxin. The plasma thromboxane and prostaglandin I2 concentrations were increased in equine endotoxic shock. Increased thromboxane concentration was associated with the high pulmonary arterial and central venous pressures and low arterial blood pressure in the minutes immediately after the ponies were given endotoxin. The increased prostaglandin I2 concentration was associated with systemic hypotension at 1 to 2 hours after endotoxin. Treatment of ponies with flunixin meglumine after endotoxin was given (group B) prevented the prostaglandin I2 rise and the associated hypotension. Treatment with fluixin meglumine before endotoxin was given prevented the increase of the plasma thromboxane and prostaglandin I2 values, along with the associated hemodynamic changes.

Effects of dietary tin on zinc, copper, iron, manganese, and magnesium metabolism of adult males

The effects of dietary tin on zinc, copper, iron, manganese, and magnesium metabolism were determined in eight adult males. Subjects were fed mixed diets containing 0.11 mg tin daily (control diet) and 49.67 tin daily (test diet) in this 40-day study. The level of tin in the control diet was typical of the levels of tin found in diets that contain only fresh and frozen foods; the level of tin in the test diet was typical of the amount of tin in diets that contain 2 cups of certain canned foods. When subjects were fed the test diet they lost significantly more zinc (p less than 0.01) in their feces and significantly less zinc (p less than 0.05) in their urine. Subjects retained significantly less zinc (p less than 0.01) when fed the test diet rather than the control diet. The fecal and urinary losses of copper, iron, manganese, and magnesium were not significantly affected by the dietary treatments.

Abnormal endometrial echoes: sonographic spectrum of endometrial pathology

This report reviews the cases of 12 patients in whom ultrasound examination revealed endometrial cavity echoes that were more prominent than expected. Dilatation and curettage or hysterectomy, or both, in these patients revealed a spectrum of endometrial pathology in 83 per cent of the patients, including carcinoma in 33 per cent and normal findings in 17 per cent.

Effects of dietary tin on tin and calcium metabolism of adult males

The effects of dietary tin on tin and calcium metabolism were determined in eight adult males. Subjects were fed mixed diets containing 0.11 mg tin daily (control diet) and 49.67 mg tin daily (test diet) for 20 days each in a cross-over design. The level of tin in the control diet was typical of the level of tin found in diets that contained only fresh and frozen foods; the level of tin in the test diet was typical of the amount of tin in diets that contained several servings of certain canned foods. Subjects apparently absorbed 3 and 50% of their dietary tin intake when fed the test and control diets, respectively. Subjects lost significantly more tin in their urine, but retained significantly more tin when fed the test diet rather than the control diet. The fecal and urinary losses and serum levels of calcium were not affected by the dietary treatments.

Brain lesions in the paraventricular nuclei and catecholaminergic neurons minimize salt hypertension in Dahl salt-sensitive rats

1. The rise in blood pressure in Dahl salt-sensitive rats that received intracerebroventricular 6-hydroxydopamine was almost half that of the control rats throughout 20 weeks of high (8%) NaCl feeding. 2. The rise in blood pressure in Dahl salt-sensitive rats with bilateral complete electrolytic lesions of the paraventricular nuclei was almost half that of the control rats during 12 weeks of high (8%) NaCl feeding. 3. The bilateral complete electrolytic lesions of the suprachiasmatic nuclei enhanced the development of NaCl hypertension in Dahl salt-sensitive rats. 4. These results show that NaCl-induced hypertension in Dahl salt-sensitive rats requires the integrity of the central nervous system catecholaminergic neurones and the paraventricular nuclei for its full expression.

Potassium citrate feeding protects against nephron loss in severe sodium chloride hypertension in rats

1. Potassium citrate did not significantly increase plasma flow to the renal papilla in normotensive Dahl R rats on either low or high NaCl diets. Similarly, potassium citrate did not significantly increase papillary plasma flow in mildly hypertensive Dahl S rats on low NaCl diets. Thus potassium citrate feeding did not ordinarily alter papillary plasma flow.

2. When S rats were fed on a high (4%) NaCl diet for 24 weeks, they became severely hypertensive and developed nephrosclerosis with nephron loss. This accounted for the significant reduction in papillary plasma flow in S rats on 4% high NaCl diet with no potassium supplementation.

3. When S rats on high NaCl diet were given a supplement of KCl, they still developed severe hypertension and almost the same fall in papillary plasma flow, suggesting a similar degree of nephron loss from nephrosclerosis.

4. However, when S rats on high NaCl diet were given a supplement of potassium citrate, they still developed the same severe hypertension but, in contrast, they did not have a decrease in papillary plasma flow. This actually increased to 7% higher than in comparable S rats eating the low NaCl diet. Moreover, S rats receiving potassium citrate supplements in their high NaCl diet had a papillary plasma flow which was 34% higher than that of S rats receiving no potassium supplement in the high NaCl diet (P < 0.005) and was 19% higher than that of S rats receiving KCl supplements in the high NaCl diet (P < 0.04). This occurred even though the rats receiving potassium citrate were severely hypertensive.

5. Thus potassium citrate feeding protected against nephron loss from nephrosclerosis during severe NaCl-induced hypertension, whereas KCl feeding did not provide such protection.

Effects of dexamethasone on fibre subtypes in rat muscle

The extent to which dexamethasone treatment produced atrophy of fast-twitch (EDL) and slow-twitch (SOL) muscles in rat was investigated. The mean weight of steroid-treated EDL muscles was decreased as compared to normal, whereas SOL muscles from normal and dexamethasone-treated animals showed no significant difference. Muscle fibre diameters also showed comparatively minor changes in SOL, which consists of Type 1 (slow oxidative) and Type 2A (fast oxidative/glycolytic) fibres. Rat EDL contains, in addition to Type 1 and Type 2A fibres, two sub-populations of fast glycolytic fibres (Types 2B and 2B'). These fibre types showed the most severe degree of atrophy both after dexamethasone treatment and after denervation. The mean ratio of the weights of denervated to innervated EDL muscles was lower in steroid-treated rats than in normal animals suggesting that the atrophy produced by steroid treatment in conjunction with denervation was more than simply additive. Analysis of the proportions of histochemical fibre types in SOL and EDL showed that dexamethasone treatment produced no major alterations in the fibre type constitution of these muscles. However, further histochemical studies showed that there was relatively severe impairment of myophosphorylase activity in Type 2B' (fast glycolytic) fibres as compared to other fibre types; conversely Type 1 fibres frequently contained increased myophosphorylase. Levels of beta-hydroxybutyrate dehydrogenase were low in both normal and steroid-treated EDL but high in SOL which also showed higher general oxidative activity. It is suggested that the particular susceptibility of fast glycolytic fibres to atrophy as a result of steroid treatment may be linked to: 1 the relatively severe reduction of myophosphorylase activity in these fibres and 2 their comparative inability to utilize alternative energy sources, especially substrates derived from free fatty acids.

Sideband generation in frequency-modulated continuous-wave light through nonlinear near-resonant propagation in an atomic vapor

We have observed sideband generation in the spectrum of frequency-modulated light when the light is transmitted near resonance to the D(1) line in Na vapor. The temporal pulse reshaping that gives rise to the self-phase modulation phenomenon is in good agreement with the predictions of a one-dimensional two-level off-resonant Maxwell-Bloch computer code.

Branhamella (Neisseria) catarrhalis--a lower respiratory tract pathogen?

Branhamella (Neisseria) catarrhalis was identified as a probable respiratory tract pathogen in seven patients, four with pneumonia and three with bronchitis. Five of the B. catarrhalis isolates produced beta-lactamase. Production of beta-lactamase correlated with penicillin resistance by the standardized disk diffusion method and also with high minimal inhibitory concentrations of penicillin for the two strains which were tested.