Dynamic control of breathing during exercise and hypercapnia

The dynamic influences of end-tidal CO2 and exercise on ventilation are compared when CO2 and exercise are imposed separately and when they are imposed simultaneously. Five human subjects are studied. The subjects performed three trials: random work rate forcing, random CO2 inhalation and their simultaneous loading. The work rate was varied between 20 and 80 W as a pseudorandom binary sequence. The concentration of inspired CO2 was varied randomly between 0 and 7 per cent, adjusted so that it produced approximately the same amount of ventilatory fluctuations as the random work load. The relative contribution of each variable was analysed using multivariate autoregressive analysis at frequencies ranging from 0.1 to 1 cycle min-1. The results show that the dynamics of the response to CO2 inhalation, exercise and their combination are nonlinear and that the combination of CO2 inhalation and exercise magnifies the nonlinear behaviour. Ventilation is largely unaffected by either work rate or end-tidal CO2 at 1 cycle min-1. During simultaneous CO2 and work rate forcing, ventilation tends to follow the change in the end-tidal CO2.

Detection of cholera toxin by a highly sensitive bead-enzyme linked immunosorbent assay

A bead-enzyme linked immunosorbent assay (bead-ELISA) for detection and quantification of cholera toxin (CT) in broth cultures of Vibrio cholerae O1 has been developed. Under optimal buffer and pH conditions the bead-ELISA could consistently detect 40 pg/ml of CT. None of the ingredients of commonly used media for in vitro culture of V. cholerae O1 hindered the performance of the bead-ELISA. Evaluation of the sensitivity and specificity of the bead-ELISA against the commonly used reversed passive latex agglutination (RPLA) test for detection of CT was performed using a collection of 239 strains of V. cholerae O1 (including both biotypes and serotypes) which were examined by a gene probe encoding for the A1 subunit of CT. Although both the assays were highly specific, the bead-ELISA was more sensitive than the RPLA. Quantification of CT by the bead-ELISA revealed that the concentration of CT produced by the strains of V. cholerae O1 which were negative by the RPLA was lower than 1 ng/ml and therefore below the minimum detection ability of the RPLA. The bead-ELISA is a simple, specific and highly sensitive assay for routine detection of CT and is recommended for routine use in clinical microbiology laboratories.

Laboratory rodent models for the tapeworm-stage of Taenia saginata and other related taeniid species

Attempts were carried out to establish alternative definitive host systems for Taenia saginata, T. crassiceps, T. hydatigena, Echinococcus multilocularis and E. granulosus, in rodents. Following oral inoculation of cysticerci or protoscoleces, the tapeworm-stage development and sexual maturation of the 5 taeniid species in the intestine of a golden hamster (GH) and Mongolian gerbil (MG), both treated with prednisolone, were examined. Sexually mature T. saginata tapeworms were recovered from MG pretreated with prednisolone. The life cycles of E. multilocularis can be completed in MG and T. crassiceps in both MG and GH. T. hydatigena and E. granulosus developed to a certain extent at the tapeworm stage in MG pretreated with prednisolone. Potential use of rodents as an alternative definitive host for taeniid species is discussed.

[A case of left coronary ostial obstruction due to syphilitic aortitis]

Coronary ostial stenosis is a rare lesion, which is a complication of syphilitic aortitis, Takayasu's aortitis, aortic valve disease, and familial hypercholesterolemia. We present a case of left coronary ostial obstruction due to syphilitic aortitis. A 67 years old man was admitted to our hospital for evaluation of a ten year history of angina on exertion. On physical examination, the only abnormal finding was a grade 2/6 high-pitched diastolic murmur. Coronary risk factor was not detected from biochemical results, but both the TPHA and FTA-ABS test were positive. Treadmill stress test showed more than 2 mm ST segment depression associated with chest pain. Coronary angiography revealed complete obstruction of left coronary ostium with good collaterals from the right coronary artery. The coronary arterial tree was otherwise normal. Furthermore, aortagraphy showed a moderate degree of aortic regurgitation. From the examination of previous reports including our own case, we think that the angiographic features of syphilitic coronary ostial stenosis can be summarized as below. 1. Coronary artery stenosis is generally limited to the ostium. 2. The grade of stenosis almost always shows more than 90% stenosis, and sometimes bilateral coronary ostium can be affected. 3. Aortic regurgitation is frequently noted, associated with coronary ostial stenosis.

Sensation and control of breathing: a dynamic model

A dynamic model of the CO2 respiratory control system is proposed, which can provide a qualitative basis for predicting breathing sensations. The discomfort index, which represents breathing sensations, is assumed to be composed of two sources: the arterial CO2 level and the respiratory motor command. The respiratory controller receives inhibitory neuromechanical and excitatory CO2 signals from the plant. The CO2 signal is enhanced by exercise stimuli. This dynamic multiplicative-type controller is used in simulations of key experiments: exercise and CO2 rebreathing with and without resistive loading. The dynamics of the discomfort index, the respiratory motor command, ventilation, and arterial CO2 concentration conform to the experimental data. The perceptual sensitivity to CO2 relative to respiratory effort is significantly correlated with the slope of hypercapnic ventilatory response. This result shows a clear linkage between ventilatory response and breathing sensations. Although it is shown that the automatic controller effectively minimizes the discomfort index for perturbations about an operating point under certain conditions, the discomfort index itself does not seem to be an underlying control principle of the proposed automatic controller model. Rather, breathing sensations may influence ventilatory responses by modifying the output of the automatic controller.

[The relationship between the aortic pulse wave velocity and osteoporosis in elderly women]

The relationship between arteriosclerosis and osteoporosis (OP) was assessed in 20 elderly women. The aortic pulse wave velocity (PWV) was used as the index of arteriosclerosis and bone mineral content (BM) of the vertebral body, which was measured by quantitative computed tomography, was used as an index of OP. PWV and BM showed a significant correlation with aging (PWV and age: r = 0.466, p less than 0.05, BM and age: r = -0.487, p less than 0.05). In the group in which the serum alkaline phosphatase (ALP) was higher than 180 IU/l (n = 11), there was a significant inverse correlation between PWV and BM (r = -0.728, p less than 0.02). On the other hand, there was no correlation between PWV and BM in the group in which ALP was lower than 180 IU/l (n = 9). These results suggest that in cases with OP and high levels of ALP, calcium (Ca) seems to be released from the bone system and transferred to the wall of the aorta. The mechanism and pathogenesis of this Ca transference is unknown and should be investigated.

Phenotypic changes in hepatic mast cells accumulating around the metacestodes of Taenia taeniaeformis in rats

Staining properties, kinetics and degranulation of the hepatic mast cells (HMC) accumulating around the metacestodes of Taenia taeniaeformis in the liver of rats were studied. Two different types of HMC, designated as Type I and Type II, could be classified according to histochemical properties and response to compound 48/80. Type I cells resembled mucosal mast cells (MMC), whereas Type II did not. HMC, mostly Type I, were observed from day 14 postinfection (PI), while Type II were seen only from day 28 PI. On day 28 PI, Type II represented a transitional staining pattern between MMC and connective tissue mast cells (CTMC). The ratio of Type II to Type I increased gradually with the course of infection and was about 1 to 1 on day 70 PI. At this time, most of the HMC that constituted Type II as well as CTMC could be stained with berberine sulfate. While the phenotypic change of HMC to CTMC was found in the middle and inner capsular layers, most of the HMC in the outer capsular layer maintained the phenotype of MMC. The present results suggest that hepatic mast cells increased as the MMC phenotype, then showed the heterogeneity in which the transitional form of mast cells emerged followed by the appearance of the CTMC type.

[Isolation of Vero toxin-producing Escherichia coli (VTEC) from imported meats]

One hundred and four samples of various imported meats obtained from the stores and supermarkets in Matsuyama-city and Iyo-city from November, 1987 to October, 1988 were examined and two strains of Vero toxin-producing Escherichia coli were isolated: one was from beef from Australia and the other was from pork from Canada. By bead-ELISA, it was confirmed that the strain from beef produced Vero Toxin 1 (VT1) and Vero Toxin 2 variant (VT2vh) and the strain from pork produced VT2vh. These results suggest that imported meats may be contaminated with VTEC and thus are possible sources of human VTEC infection, such as hemorrhagic colitis and hemolytic uremic syndrome.

Contribution of chemical feedback loops to breath-to-breath variability of tidal volume

We tested whether chemical feedback loops contribute to the breath-to-breath correlations seen in respiratory cycle parameters. We have analyzed tidal volume (VT) of seven anesthetized, vagotomized, spontaneously breathing rats and the peaks of the 'integrated' phrenic neurograms (P) of another twelve anesthetized, vagotomized, paralyzed and artificially ventilated rats. Animals were studied while breathing 100% O2, 4% CO2 in O2 and/or room air. Our analysis consisted of fitting a first-order autoregressive (AR1) model to each measured variable in steady-state conditions. We found that: (1) breath-to-breath fluctuations of VT could be described by a first-order autoregressive model in which the fluctuation of VT on each breath from its mean level is correlated with that of the immediately preceding breath; (2) breath-to-breath fluctuations of P were not correlated with those of previous breaths, because successive values of P were uncorrelated random variables. Hypercapnia enhanced correlations in VT (3 rats) but not in P (12 rats). We propose that breath-to-breath correlations of VT in anesthetized, vagotomized and spontaneously breathing rats may reflect the effects of noise in respiratory chemical feedback loops.

The relationship between 24 hour total heart beats or ventricular arrhythmias and cardiopulmonary function in patients with Duchenne's muscular dystrophy

To evaluate the relationship of 24 hour total heart beats (THB) or ventricular arrhythmias and cardiopulmonary function, 29 patients with Duchenne's muscular dystrophy (DMD) were studied using Holter electrocardiographic and echocardiographic recordings. The THB were 144,428 +/- 12,237 beats per 24 hours in the child group (8 to 15 years, n = 12) and 136,355 +/- 19,991 beats per 24 hours in the adult group (16 to 25 years, n = 17). The THB in the adult group significantly correlated well with % VC (r = -0.74), PaCO2 (r = 0.67), PaO2 (r = -0.59) and the respiration rate (r = 0.71), but not in the child group. In both groups, the echocardiographic parameters of the left ventricular size and function (left ventricular dimension, ejection fraction and D/S ratio) did not significantly correlate with the THB. Premature ventricular contractions (PVCs) were observed in 14 of the 29 patients (48.3%), and high risk PVCs (Lown's grade 3-4b) were observed in 11 of these 14 patients (78.6%). Echocardiographic parameters of the left ventricular function in the high risk PVC group were significantly deteriorated as compared with the low risk PVC group (Lown's grade 0-2) (p less than 0.02-p less than 0.001). We conclude that the THB in the adult group was mainly related to depressed pulmonary function, and the severity of the PVCs in both the adult and child groups was mainly related to the degree of left ventricular dysfunction.

Long-term observation of cardiac function in Duchenne's muscular dystrophy. Evaluation using systolic time intervals and echocardiography

Cardiac involvement is common in patients with Duchenne type muscular dystrophy (DMD). However, published reports of long-term follow-up studies in the same patients are very rare. The purpose of this study was to clarify the natural course of cardiac dysfunction in DMD, and to analyze the relationship between the deterioration of cardiac function and skeletal muscular function. The cardiac function was serially evaluated for 2-12 years in 34 patients with DMD. The systolic time intervals and echocardiography were used for evaluating the cardiac function. The PEP/ET (pre-ejection period/ejection time) of systolic time intervals significantly deteriorated in 9-12 years (p less than 0.001). The maximal systolic and diastolic endocardial velocity (MSEV and MDEV) and the D/S ratio of echocardiography significantly deteriorated in 5 years (p less than 0.001). The D/S ratio is the ratio of the mean systolic velocity and the mean diastolic velocity of the left ventricular posterior wall. In almost half the patients, the deterioration of these parameters was correlated with that of Swinyard's stage. The Swinyard's functional ability stage demonstrates the grade of the skeletal muscular dysfunction. However, there was no correlation between the deterioration of cardiac function and Swinyard's stage in the other half of the patients. Correlation coefficient in the whole group was 0.32 (p = n.s.) between the PEP/ET and Swinyard's stage, and was -0.15 (p = n.s.) between the D/S ratio and Swinyard's stage. Although the mean left ventricular ejection fraction calculated using echocardiography was slightly decreased for 5 years, no significant change was detected in the whole group. One patient had progressive deterioration of left ventricular function despite mild skeletal muscular dysfunction, and died from congestive heart failure. The cardiac dysfunction was predominant. We named it 'cardiac type' DMD. Since deterioration of cardiac function was not always correlated with deterioration of skeletal muscular function (Swinyard's stage), cardiac function must be carefully monitored in patients with DMD.

Development and sexual maturation of Taenia crassiceps (Cestoda) in the golden hamster

The development of cysticerci of Taenia crassiceps to mature tapeworms in the intestinal tract of cortisone-treated and untreated golden hamsters is described. The development of the worms in untreated hamsters is as follows. Maturation and branching of the uterus and the presence of ova in the uterus were observed on day 15 postinfection (PI). By day 21 PI, fertilization had taken place, as evidenced by the presence of sperm in the seminal receptacle. On day 28 PI, shelled eggs were observed in feces. The rate of development of the worms in cortisone-treated hamsters was similar to that observed in untreated hamsters. More worm recovery and a longer period of worm survival were seen in the cortisone-treated than in the untreated hamsters. Thus, both cortisone-treated and untreated golden hamsters can produce normal gravid individuals of T. crassiceps.

Demonstration of RNA N-glycosidase activity of a Vero toxin (VT2 variant) produced by Escherichia coli O91:H21 from a patient with the hemolytic uremic syndrome

A new Vero toxin purified from Escherichia coli O91:H21 isolated from a patient with the hemolytic uremic syndrome (VT2vh) was shown to inhibit elongation factor 1-dependent aminoacyl-tRNA binding to ribosomes, resulting in inhibition of protein synthesis in rabbit reticulocytes. VT2vh, like Shiga toxin, VT1 and VT2, showed RNA N-glycosidase activity and cleaved the N-glycosidic bond of the adenosine residue at position 4324 in 28S ribosomal RNA.

Growth of a Japanese isolate of Taenia crassiceps in intermediate and definitive hosts

Higher infection rates were observed in gerbils and voles than in ICR mice after oral inoculation with eggs of a Japanese isolate of Taenia crassiceps. Asexual reproduction of T. crassiceps cysticerci was observed in all gerbils and voles infected i.p. with the cysticerci. However, ICR mice and Wistar rats were not suitable for the asexual proliferation of T. crassiceps. The hooks of cysticerci from mice were smaller than those from gerbils. In experimentally infected puppies, parasite development was noted as follows: strobilation and initial differentiation of the genital primordia on day 7 postinoculation (p.i.), appearance of the testes on day 9, observation of the ovaries on day 10, and development of the lateral branches of the uterus on day 15. The prepatent period was 27-31 days. After day 15 p.i., most of the worms were recovered from the middle third of the small intestine. The number of proglottids shed per day by each strobila was about 1. The number of eggs contained in a gravid segment was about 13,000.

[Bacteriological investigation on an outbreak of acute enteritis associated with verotoxin-producing Escherichia coli O111:H-]

An outbreak of acute enteritis in children aged one to thirty-three months occurred from June 10th to 23rd, 1986, at a private orphanage in Matsuyama City. Twenty-two out of 23 children suffered from diarrhea. Nine of the 22 children excreted bloody stool. Fever and vomiting were observed with a few patients. One of them, a 33-month-old girl, developed hemolytic uremic syndrome, and died twelve days after the admission. Escherichia coli O111:H- was isolated from fecal specimens of 7 out of 15 patients. The culture filtrate of the isolate caused fluid accumulation in ligated ileal loops in a rabbit, and was lethal to mice. It was found that all isolates produced two kinds of Vero toxins (VT1 and VT2, or shiga-like toxin I and II). The amount of VT2 produced in vitro was about 10 times more than that of VT1.

Rapid growth of a meningioma during pregnancy: relationship with estrogen and progesterone receptors--case report

Meningiomas are often described as hormone-dependent because of their preponderance in females and their tendency to clinically manifest during or after pregnancy. We describe a case of meningioma that grew rapidly during two pregnancies over a 2-year period. The tumor's rapid growth was confirmed by high-resolution computed tomography. Its estimated doubling time was 110 days. The tumor was removed and found to be a benign meningothelial meningioma. The tumor tissue was positive for estrogen receptors (ERs) and progesterone receptors (PRs). In nine cases, including this one, in which ERs and PRs were measured, the positive rate was much higher for PRs than for ERs; only two were positive for ERs. In the case reported here, it is presumed that the growth of the meningioma was influenced by estrogen and/or progesterone binding to receptors, although it is unclear whether one or both hormones was involved.

[Limitation of RI imaging in evaluating lung function test--development of new methods]

We developed two methods for determining the regional distribution of (1) RV/TLC and air trapping during forced expiration and (2) the ratio or pulmonary blood volume to blood flow. 1) The regional distributions of RV/TLC and air trapping ratio: A.T.R. (air trapping caused by forced expiration) were measured in respiratory disease cases and normal subjects using Xe-133 gas. In normal subjects, RV/TLC gradually decreased from the apex to the base of the lung. A.T.R. was very low in all lung fields. In chronic emphysema (CPE), both RV/TLC and A.T.R. were much higher than the value in normal subjects at the highly diseased areas. In contrast, in case of diffuse panbronchiolitis (DPB), RV/TLC remained within the normal range and A.T.R. was increased considerably in the diseased regions. These results suggest that airway obstruction occurs only during the forced expiration in DPB. 2) The regional distribution of the ratio of pulmonary blood volume to blood flow (tau p) were measured in a normal subject and a case of mitral regurgitation. In both subjects, the distribution of 1/tau p consisted of three zones: upper, middle and lower. The distribution of 1/tau p was constant in the middle zone, but, in the upper and lower zones, it decreased in proportion to the distance from the middle zone. In the case of mitral regurgitation, the middle zone shifted to the apex. Applying the results to the lung perfusion model proposed by West, it was suggested that these phenomena might reflect the increase of the pulmonary venous pressure and the perfusion disorder in the lower lung.

Purification and some properties of a Vero toxin from a human strain of Escherichia coli that is immunologically related to Shiga-like toxin II (VT2)

A cytotoxin to Vero cells (Vero toxin), which was immunologically related to Shiga-like toxin II (SLT-II) (or VT2), was purified from a stain of Escherichia coli isolated from a patient with hemolytic uremic syndrome. The toxin was active on Vero cells but much less active on HeLa cells, a property similar to that of the recently identified SLT-II variant from E. coli strains that caused edema disease of swine. Thus the toxin purified in this report was tentatively named Shiga-like toxin II variant (Vero toxin 2 variant). The purification procedures consisted of ammonium sulfate fractionation, DEAE-Sepharose CL-6B column chromatography, chromatofocusing column chromatography, and repeated high performance liquid chromatography (HPLC) on TSK-gel G-2000SW column and on TSK-gel DEAE-5PW columns. About 90 micrograms of purified toxin was obtained from 451 of the culture supernatant with a yield of about 16%. The purified toxin consisted of A and B subunits of molecular sizes similar to those of SLT-II (VT2). The isoelectric point of the purified toxin was 6.1, which was different from that of SLT-II (VT2) (pI = 4.1). In an Ouchterlony double gel diffusion test, purified toxin and SLT-II (VT2) formed precipitin lines with spur formation against anti-purified toxin and anti-SLT-II (anti-VT2), respectively. The purified toxin was cytotoxic to Vero cells, about 6 pg of the toxin killing 50% of the Vero cells, and showed lethal toxicity to mice when injected intraperitoneally, the LD50 being about 2.7 ng per mouse.

[Evaluation of respiratory disability in patients of respiratory diseases using relationships between ventilatory drive, ventilation and thoracic pump function during exercise]

We studied the parameters of breathing control during exercise in patients with respiratory diseases for the evaluation of respiratory disability. The ventilatory drive during the same load exercise was increased in patients with respiratory diseases compared with that in normal subjects. In addition, the ratio of ventilation to ventilatory drive during exercise was decreased in patients with respiratory diseases. Impairment of rapid thoracic movement was suggested to be one of the mechanical limitations for ventilation in these patients, based on the findings of smaller esophageal pressure fluctuation during maximum ventilation of 40 respirations per minute than that in normal subjects. Flow at 0.1 sec after initiation of inspiration was designated V0.1. The increase of the ratio of V0.1 at rest to that at maximum voluntary inspiration (V0.0 (rest)/V0.1 (max)) indicate the grade of respiratory disability showing the impossibility of rapid movement of thorax as a parameter of thoracic pump function. It was recognized that the decrease of VE/P0.1 during incremental exercise indicated ventilatory insufficiency.

Toxin profiles of Vibrio cholerae non-O1 from environmental sources in Calcutta, India

A collection of Vibrio cholerae non-O1 isolated from the aquatic environs of Calcutta, a cholera-hyperendemic area, were examined for the production of cholera toxin (CT), Shiga-like toxins (Vero toxins), heat-stable enterotoxin, and hemolysins. Two (0.5%) V. cholerae non-O1 isolates produced CT. The DNA from both these isolates also hybridized with a DNA probe containing sequences encoding the A subunit of CT. None of the strains produced Shiga-like toxins or heat-stable enterotoxin. Hemolytic activity was observed in 89.7% of the strains, of which 36.1% exhibited biological activity in the suckling mouse. However, none of them produced a hemolysin that cross-reacted with the thermostable direct hemolysin of Vibrio parahaemolyticus. It appears from this study that a small percentage of environmental V. cholerae non-O1 strains do possess the potential for causing cholera-like diarrhea.

[Effect of ACNU against experimental brain tumor--immunohistochemical study using anti-BrdU monoclonal antibody]

We have studied the efficacy of intrathecal ACNU against experimental leptomeningeal tumors. In the present report, the effect of ACNU on the growth kinetics of the tumor was evaluated by the immunohistochemical technique using anti-BrdU monoclonal antibody. The experimental leptomeningeal tumor was developed by inoculation of Walker 256 carcinosarcoma cells into the cisterna magna of rats. Seven days after the inoculation of tumor cells, the animals were treated either by intravenous (15 mg/kg) or intrathecal (1.5 mg/kg) ACNU. Four, 12, 24, 48, 96 or 144 hours after treatment, the animals received intravenous BrdU (200 mg/kg). Thirty minutes thereafter, they were sacrificed and the brain was removed. L. I. was calculated by counting the immunoreactive tumor cells. L. I. of the tumor without treatment on the seventh day after inoculation was over 40%. L. I. began to decrease 24 hours after intravenous ACNU, and remained 11% up to 96 hours. On the other hand, L. I. already decreased to 20% 4 hours after intrathecal ACNU and remained to be low (17%) up to 48 hours. However, L. I. increased to 38% at 96 hours. Thus, the effect on the growth kinetics of the tumor differs between intravenous and intrathecal ACNU. These results are considered to be useful informations for determining the optimal dosage of the antineoplastic agent against the brain tumor and developing the effective combination chemotherapy.

Immunoelectron microscopic studies on spore coat proteins of Bacillus megaterium

An immunochemical staining technique for the spore coat proteins of Bacillus megaterium ATCC 12872 was developed using colloidal gold as a second antibody. For reducing the non-specific immunogold binding and increasing the specific binding, the affinity-purified IgG was used as a first antibody. In sporulating cells at t10, gold particles were found not only in the spore coat but also in the mother cell cytoplasm, suggesting that some coat proteins were synthesized in the cytoplasm. Use of the specific affinity-purified antibody to 48K-protein demonstrated that this protein was one of the components of the outer coat.