The relationship of resting ventilation to mouth occlusion pressure. An index of resting respiratory function

In order to examine the relationship of mouth occlusion pressure (MOP), an index of central inspiratory neuromuscular drive, to age and sex and to resting ventilation (VE), measurements were made in the seated posture in 84 healthy, normal subjects (38 men, 46 women; ages 18-72 years, mean +/- SD = 39.8 +/- 14.5 years) and in 79 patients with either airways obstruction (n = 63) or restrictive lung disease (n = 16). In the normal subjects, there was no significant relationship between age or sex and MOP (expressed as P0.1), which is the mouth pressure developed against a complete occlusion at 0.1 s after the beginning of inspiration, and dP/dtmax, the maximal rate of rise of this pressure; mean +/- SD for P0.1 = 0.75 +/- 0.32 cmH2O, and dP/dtmax = 19.41 +/- 10.10 cmH2O/s. Similarly, there was no significant relationship between age or sex and VE/P0.1 or VE/dP/dtmax. In 99 percent of normal subjects (83 of 84), VE/P0.1 was greater than 8.0 L/min/cmH2O, whereas in only 1 of the 79 patients was the value greater than 7.9 L/min/cmH2O. While the mean values of P0.1 and dP/dtmax were significantly different between normal subjects and patients, there was considerable overlap, whereas the ratio VE/P0.1 or VE/dP/dtmax provided excellent differentiation between normal subjects and patients with lung disease. This index, which is easily measured and requires minimal patient cooperation, provides valuable information in the clinical assessment of ventilatory drive and lung mechanics.

Pulmonary talc granulomatosis in a cocaine sniffer

The development of pulmonary granulomatosis following intravenous injection of medications intended for oral use has been well described previously. Talc is the most commonly implicated agent. We present a case of talc granulomatosis which developed in a patient following cocaine sniffing and suggest that this may be the cause of development of granulomata in drug addicts who deny any history of intravenous drug abuse.

Oscillatory and step response electromechanical phenomena in human and bovine bone

Bone generates electrical potentials or strain-related potentials when mechanically deformed. These electrical potentials may be partially responsible for the remodeling process which bone experiences in response to mechanical loads. A large body of evidence suggests that streaming potentials are the dominant mechanism responsible for strain-related potential generation in fluid saturated bone. Recently, biphasic poroelastic theory has been coupled to electrokinetic theory in an attempt to further elucidate this mechanism. The work reported here expands the experimental evidence in support of this theory. Experimental results which characterize electrical and mechanical phenomena in both wide frequency oscillatory and step response testing of 47 human and bovine bone specimens are reported. These results also include data from experiments in which the viscosity and conductivity of the solutions permeating 10 human and bovine bone specimens were varied. A specially designed mechanical testing of bone specimens. Testing procedures, which were optimized for strain-related potential measurement, were developed. These included procedures for varying testing solution viscosity and conductivity. The experimental data was analyzed using descriptive and inferential statistical techniques and linear and nonlinear regression methods. The following objectives were established for the work reported here: (1) to confirm the existing experimental results; (2) to attempt to obtain a successful correlation between theoretically predicted and experimentally observed mechanical phenomena; (3) to extend the experimental results over the wider frequency range of 0.05-100 Hz; (4) to test the theory in the time domain; (5) to test the theory for changes in viscosity and conductivity of the permeating fluid; and (6) to extend the experimental testing to include human bone specimens. All of these objectives were met except that a highly variable correlation between the theoretically predicted and experimentally observed mechanical phenomena was obtained. Patterns in these data are explored and the possible causes of the highly variable correlation are discussed. The results strongly suggest an electrokinetic origin for the observed electrical potentials. The microporosity of bone appears to be the location in which this mechanism operates.

Airways responsiveness determined by consecutive histamine challenges in asymptomatic asthmatics

The effect of two consecutive histamine inhalation challenges on airways responsiveness was assessed in a group of eight nonsmoking nonmedicated asthmatics aged 19-27 yr. All subjects had a base-line forced expiratory volume in 1 s (FEV1) of greater than 80% of their predicted normal value before the initial challenge and were allowed to recover to greater than 95% of the initial base-line FEV1 value before the second challenge was initiated. The average airways recovery time after the first challenge was 44 min but ranged between 30 and 90 min. The mean +/- SD values of cumulative histamine dose units provoking a 20% decrease of the FEV1 from the buffer control value (PD20FEV1) were 10.79 +/- 5.95 determined with the first and 30.50 +/- 46.36 with the second challenge (P greater than 0.05). We conclude that sequential histamine challenges performed in mild asthmatics with closely controlled prechallenge airways function are well tolerated. Although some variance does exist in intersubject airways recovery time and in intra-subject histamine airways responsiveness determined by sequential challenges, our data do not support recent observations (J. Appl. Physiol. 63: 1572-1577, 1987) that histamine tolerance is a characteristic finding associated with bronchial asthma.

Transdermal scopolamine attenuates methacholine-induced bronchospasm

Anticholinergic agents have been widely used in the management of asthma. The use of scopolamine has been limited by significant side effects. Transdermal delivery of scopolamine (TS) has, however, been used successfully for the prevention of motion sickness. The purpose of this study was to determine if TS would decrease methacholine-induced bronchospasm in a group of subjects with mild asthma. Bronchoprovocational challenges with inhaled methacholine were performed on three separate occasions in 10 male subjects who each had a past history of asthma. After a baseline challenge, each subject received, in a double-blinded fashion, either a placebo patch or TS patch. The challenge was then repeated after at least 36 hours, and the alternate patch was then dispensed. The provocative dose producing a fall in FEV1 by 20% from baseline was then calculated by linear regression analysis. No significant change in baseline pulmonary function was noted with placebo patch or TS. With the use of TS, there was a small but significant increase in the provocative dose producing a fall in FEV1 by 20% from baseline for the group (p less than 0.05). In conclusion, we were able to demonstrate that a TS patch worn for a short period of time, can significantly decrease airway reactivity to methacholine in some patients with hyperactive airways.

Bronchoprovocational challenges in the assessment of the efficacy of therapeutic agents

Bronchoprovocational challenge techniques are useful clinical and research tools for evaluating airway hyperreactivity. Not only are they useful in guiding management of patients with asthma, but also are commonly used to assess the efficacy of bronchodilating agents. The mechanisms involved in the development of bronchoconstriction are poorly defined, but continued work with challenge procedures may increase our understanding of the factors responsible for asthma. This paper will review some of the challenge techniques currently in use and outline the usefulness and limitations of these procedures.

Large cell lymphoma presenting as a coronal penile lesion

Although the majority of penile malignancies are primary epithelial carcinomas, consideration of secondary involvement, especially from lymphoma, is important, since there are alternatives to the standard therapeutic approach of penile amputation.

The role of atmospheric pressure variation in the development of spontaneous pneumothoraces

It has been postulated that spontaneous pneumothoraces (SP) develop because of rupture of subpleural blebs, and that atmospheric pressure changes (delta AP) may be contributory. A 5-year retrospective analysis of SP admissions was carried out to determine if delta AP do play a role in SP development. Using a 36-yr record of hourly delta AP, a normative background for delta AP was constructed. A fall in AP below the fifth, or a rise above the ninety-fifth percentile during these time periods, was classed as "unusual." Atmospheric pressure changes in the 4 days prior to SP were analyzed. The expected frequency of SP occurring by chance, if no relationship to delta AP existed, was also calculated. A total of 192 cases of SP was analyzed. Traumatic pneumothoraces were excluded. The majority of cases (72%) had been exposed to at least one "unusual" delta AP in the 4 days prior to onset of symptoms. Among those with four or more "unusual" exposures, SP occurrence was significantly more frequent than expected by chance alone (p less than 10(-10]. A strong positive association between delta AP and SP was not found in all cases, as delta AP are unlikely to be the only causative factor for SP. This finding of a relationship with ambient pressure changes lends support to the theory that SP develop as a result of rupture of subpleural blebs.

BCG vaccination in leprosy: final results of the trial in Karimui, Papua New Guinea, 1963-79

The efficacy of BCG vaccine in preventing the clinical manifestations of leprosy in a tuberculosis-free area of Papua New Guinea is reported. Between 1963 and 1966 a total of 5356 subjects, randomized to receive BCG or saline inoculations, were examined for leprosy before the vaccination and surveillance was continued until 1979. BCG afforded 48% protection against clinical leprosy, being most effective against borderline tuberculoid leprosy and in children vaccinated when under 15 years old. Protection was evident within 12 months in those vaccinated between the ages of 10 and 15 years but was delayed in other age groups. There was evidence for accelerated manifestations of tuberculoid leprosy in children vaccinated when under 5 years of age. Tuberculin sensitivity was more likely to be sustained following multiple BCG inoculations; vaccinees with sustained tuberculin sensitivity had the lowest incidence of leprosy, but protection was also evident in tuberculin-negative vaccinees. These results may have implications for ongoing trials of leprosy vaccine incorporating BCG.

How many spirograms for a histamine challenge?

Several reports have shown that a prior deep inspiration exerts a blunting effect on pharmacologically induced bronchoconstriction. Inspiration to total lung capacity is a mandatory requirement for valid determination of the FEV1, and thus, the FEV1 may underestimate the magnitude of induced airway obstruction. The present study was designed to assess the effect that the performance and separate analysis of 2 consecutive FEV1 maneuvers (FEV(1)1, FEV(1)2), obtained at different levels of histamine-induced bronchoconstriction, may have on the final interpretation of a histamine challenge. Eight asymptomatic nonsmoking asthmatics (mean age, 24 yr; range, 19 to 27 yr) underwent a total of 16 histamine challenges. Paired FEV1 measurements (FEV(1)1, FEV(1)2) were obtained after inhalation of buffer solution (control) and 3 min after inhalation of aerosolized, serially diluted, histamine diphosphate solutions. A significant airways response (FEV1 decreasing by 20% or more from the control value) was observed in all subjects after inhalation of 5 mg/ml of histamine or less, indicating histamine airway hypersensitivity. At lower doses of histamine the mean values for FEV(1)1 and FEV(1)2 were similar to the control value. At higher histamine doses FEV(1)2 was consistently higher than FEV(1)1 (p = 0.007) and exceeded FEV1 1 by a mean of 9% after inhalation of the provocational histamine concentration; delta FEV1(FEV(1)2-FEV(1)1) was correlated with the log10 of cumulative inhaled histamine dose units (p = 0.040). Assuming that the difference between corresponding FEV1 determinations at a given level of induced bronchoconstriction is a direct consequence of changes in lung mechanics induced by deep inspiration, we are led to conclude that during histamine inhalation challenges, only 1 spirogram should be performed at each level of induced bronchoconstriction.

Food preferences of dogs housed in testing-kennels and in consumers' homes: some comparisons

This work assessed the extent to which the food preferences of dogs housed in testing-kennels are representative of those reported for dogs housed in consumers' homes. Experiment 1 compared two-pan preference data from kennel-dogs and home-dogs fed canned, semi-moist, or dry food products. Kennel- and home-dogs performed similarly on the canned-products test, but differed significantly on the semi-moist and dry products tests. Experiment 2 demonstrated that the discrepancies between kennel- and home-dogs were likely due to differences in feeding history prior to the test. Experiment 3 showed that the effects of prefeeding with a single food are relatively short-lived in kennel-dogs, lasting for only a few days. In home-dogs preferences were more stable.

The influence of a feed additive level of virginiamycin on the course of an experimentally induced Salmonella typhimurium infection in broilers

The purpose of this study was to determine the effect of virginiamycin on the course of an experimentally induced infection of Salmonella typhimurium in broilers. Several parameters were evaluated, including effects on the persistence and duration of shedding of the infecting Salmonella organism and its antibiotic resistance patterns. Virginiamycin was administered to the experimentally infected group for 8 weeks in feed at concentrations of 25 g/ton. This was compared to an infected control group not receiving the antibiotic. No effects were exhibited by virginiamycin on Salmonella typhimurium shedding and antibiotic resistance patterns.

Acedapsone treatment of leprosy patients: response versus drug disposition

In 22 lepromatous Filipino patients receiving their first injection of 225 mg acedapsone (DADDS), dapsone (DDS), and monoacetyl DDS (MADDS) were present in plasma in approximately equal quantities. Peak levels of parent drug, DDS, and MADDS occurred between 22 and 35 days. The half-times of disappearance (T1/2) from plasma were 43 days for DDS and MADDS and 46 days for DADDS. Acetylator phenotyping with sulfamethazine (SMZ) and DDS showed that 17 patients were rapid and 5 patients were slow acetylators. Correlations between acetylation of SMZ and DDS after DDS and of acetylation of DDS after DDS and DADDS were highly significant. However, acetylation of DDS after DADDS did not differentiate the patients into acetylator phenotypes. The T1/2 of DDS after DDS in the patients was directly related to the minimum levels of DDS at 77 days after DADDS treatment. These minimum levels were 8-fold higher than the minimum inhibitory concentration (MIC) of DDS for Mycobacterium leprae in mice and rats, but not all patients responded satisfactorily. No relationship could be demonstrated between the bacteriologic response and any of the pharmacologic parameters examined in these Filipino patients. In a companion study, minimum levels of DADDS, MADDS, and DDS were determined in 447 leprosy patients of all disease types from the Karimui District of Papua New Guinea who had been receiving 225 mg DADDS every 70 to 80 days for the past 5 years. All patients exhibited DDS levels above the MIC of DDS for M. leprae, no significant differences in plasma sulfone levels were found among disease types, no relationship between rate of healing in paucibacillary patients and sulfone levels were found, and type of response in multibacillary patients and sulfone levels were unrelated. No substantial accumulation of the sulfones in the Karimui patients receiving continuous therapy with DADDS for 5 years was indicated from a comparison with the levels in the Filipino patients following a single injection of DADDS.

Acedapsone (DADDS) treatment of leprosy patients in the Karimui of Papua New Guinea: status at six years

Acedapsone (DADDS), a repository sulfone given by injection five times a year, has been used since 1967 for the treatment of all leprosy patients in the Karimui, an area of diffic-lt access. More than 460 patients have been treated, 336 beginning in November 1967 and continuing through the latest assessment 6 years later. The injections have been well received and they have been administered very regularly. Clinical observations were begun before 1967, as a base-line of assessments was available for the patients whose disease appeared before that time. The response to DADDS therapy has been satisfactory except in 5 of the 28 multibacillary patients in whose smears solid-staining Mycobacterium leprae have reappeared. M. leprae was isolated in mice from three of these patients; one strain has been proven to be completely susceptible to dapsone (DDS), and the other two very probably are. DDS levels in the plasma of these five patients were normal and well above the minimal inhibitory concentration. The most probable explanation is that a few viable M. leprae survived in the presence of inhibitory concentrations of DDS for the 4 to 6 years during which dead bacilli were disintegrating and disappearing from the tissues. The other 23 multibacillary patients responded satisfactorily. The decrease in the number of M. leprae in the skin smears has been most prompt in patients with low initial bacterial loads and in those with borderline lepromatous diagnoses. A high initial bacterial load and a fully lepromatous diagnosis were associated with a slow initial loss of M. leprae in the 1st year, followed by a more rapid loss the next year. All of the multibacillary patients have now been treated by the addition of a 90-day course of rifampicin.