Gap junction blockade with carbenoxolone differentially affects fictive breathing in larval and adult bullfrogs

This study examined the role of gap junctional communication in the modulation of respiratory related motor output using in vitro brainstem preparations of larval (N=14) and adult (N=14) bullfrogs (Rana catesbeiana). Superfusion of the isolated brainstem for at least 1 h with the gap junction blocker carbenoxolone (CBX; 100 microM and 1 mM) dissolved in artificial cerebrospinal fluid (aCSF) elicited significant changes in respiratory-related burst frequency in both larval and adult preparations. In tadpole preparations, both concentrations of CBX significantly decreased gill and lung burst frequency over 20-40 min, with 1 mM CBX producing complete cessation of gill and lung burst activity by 40 min in all preparations. There was little or no change in other burst characteristics such as burst amplitude or duration. By contrast, superfusion of the adult brainstem preparation with CBX significantly increased lung burst frequency over 10-20 min, and caused cessation of lung burst activity with 100 microM CBX (five of seven preparations) and with 1 mM CBX (seven of seven preparations). Adult preparations that ceased activity with 100 microM CBX recovered in control aCSF, but those in 1 mM did not recover, despite up to 3 h superfusion with control aCSF. In two additional adult preparations, 1 h exposure to hypercapnic aCSF (7-10% CO2) following the cessation of fictive breathing with 1 mM CBX failed to evoke respiratory activity. The inhibition of fictive breathing in tadpoles suggests that gap junctional communication may be important for respiratory rhythmogenesis prior to the development of central CO2 chemosensitivity. Following metamorphosis to the terrestrial adult, however, gap junctional communication may contribute to regulation of respiratory frequency and possibly the transduction of central CO2 chemosensitivity.     

GABAA receptors mediate postnatal depression of respiratory frequency by barbiturates

We tested the hypothesis that barbiturates depress respiratory motor output by actions on the GABAA receptor. We examined the influence of pentobarbital sodium on nerve activity recorded from a fourth cervical (C4) ventral root (phrenic motoneuron output) in the in vitro brainstem-spinal cord preparation of neonatal rats aged 1-3 days. Bath application of pentobarbital slowed the respiratory rhythm but this effect could be reversed by drug washout or by simultaneous application of 8 microM bicuculline methiodide, a GABAA receptor antagonist. Pentobarbital up to a concentration of 80 microM (or 20 mg/l) did not change the magnitude of C4 nerve bursts. The GABAA receptor agonist muscimol evoked similar changes. The results support the hypothesis that respiratory depression by barbiturates is due to GABAA receptor-mediated inhibition, with the principal effects on rhythm generation. In the light of recent studies suggesting that GABAA receptors may be excitatory in the early neonatal period, we examined postnatal changes in the GABAergic slowing of respiratory rhythm. Stimulation of GABAA receptors slowed respiratory rhythm from the first postnatal day, with no change in efficacy over the first 3 days of life.     

Peculiarities of external respiration as a marker of activity of cell respiratory enzymes in rat brain

Rats with catatonic freezing are characterized by low motor and explorative activity in the open field test and specific pattern of external respiration, so-called strenuous respiration, which is accompanied by a higher activity of the respiratory enzymes succinate dehydrogenase and NADH dehydrogenase in the hippocampus and motor cortex. No dependencies on the brain structure and animal age are noted. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 124, No. 8, pp. 138–140, August, 1997     

5-HT at hypoglossal motor nucleus and respiratory control of genioglossus muscle in anesthetized rats

Serotonin (5-HT) from medullary raphe neurons excites hypoglossal motoneurons innervating genioglossus (GG) muscle. Since some raphe neurons also show increased activity in hypercapnia, we tested the hypothesis that serotonergic mechanisms at the hypoglossal motor nucleus (HMN) modulate GG activity and responses to CO2. Seventeen urethane-anesthetized, tracheotomized and vagotomized rats were studied. Microdialysis probes were used to deliver mianserin (5-HT receptor antagonist, 0 and 0.1 mM) or 5-HT (eight doses, 0-50 mM) to the HMN during room air or CO2-stimulated breathing. Mianserin decreased respiratory-related GG activity during room air and CO2-stimulated breathing (P<0.001), and also suppressed GG responses to CO2 (P=0.05). In contrast, GG activity was increased by 5-HT at the HMN, and was further increased in hypercapnia (P<0.02). However, 5-HT increased respiratory-related GG activity at levels lower (1 mM) than those eliciting tonic GG activity (10-30 mM 5-HT). The results show that 5-HT at the HMN contributes to the respiratory control of GG muscle.     

Modulation of breathing by phasic pulmonary stretch receptor feedback in an amphibian, Bufo marinus

This study examined the role of phasic pulmonary stretch receptor (PSR) feedback in ventilatory control, breath clustering and breath timing in decerebrate, paralysed and artificially-ventilated cane toads (Bufo marinus) under conditions designed to minimise tonic PSR feedback. Fictive breathing was recorded as trigeminal motor output to the buccal musculature. Artificial tidal ventilation, with hypercarbic gas mixtures, was either continuous or activated by the fictive breaths and was manipulated to provide differing amounts/patterns of phasic PSR feedback. The results demonstrate that increased amounts of phasic PSR feedback increase overall breathing frequency. Within multi-breath episodes there was an increase in the instantaneous breathing frequency during the later stages of the episode. The temporal relationship between a fictive breath and lung inflation influenced the duration of the pause between fictive breaths. The data indicate that phasic PSR feedback stimulates breathing by enhancing the occurrence of breathing episodes in this species but does not appear to modify the instantaneous breathing frequency during an episode.     

Diurnal changes in the number of mitoses and of DNA-synthesizing cells in tissues of young rats

Regular diurnal changes in the number of mitoses (MI) and the number of DNA-synthesizing cells (ILN) were demonstrated in the liver, epidermis, and exogenous part of the pancreas of rats aged 7 days. The character of these changes differed in the various tissues. No regular correlation was found between diurnal changes in MI or ILN.Department of General Biology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Kupriyanov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1369–1371, November, 1976.     

Why savannah monitor lizards hyperventilate during activity: a comparison of model predictions and experimental data

The functional and structural factors that limit maximal oxygen uptake (VO2 max) in lizards are not completely understood. Using an integrative model describing the interactive nature of the individual oxygen transport conductances, we performed an analysis of the oxygen transport system in the highly aerobic lizard Varanus exanthematicus with specific reference to the sensitivity of VO2 max to potential limitations in the ventilatory system. Our analysis predicts that DLO2 must increase more than three-fold at VO2 max and even with this increase in DLO2 , the VO2 max may be sensitive to factors that alter lung ventilation and/or lower lung PO2. To test the predictions of the model analysis, we experimentally determined the effects of reducing inspired O2 on VO2 max during treadmill exercise. We conclude from both our theoretical and experimental analyses that V. exanthematicus operates near the functional limits of its lung.     

Cardioventilatory effects of acclimatization to aquatic hypoxia in channel catfish

The mechanisms responsible for altering cardioventilatory control in vertebrates in response to chronic hypoxia are not well understood but appear to be mediated through the oxygen-sensitive chemoreceptor pathway. Little is known about the effects of chronic hypoxia on cardioventilatory control in vertebrates other than mammals. The purpose of this study was to determine how cardioventilatory control and the pattern of response is altered in channel catfish (Ictalurus punctatus) by 1 week of moderate hypoxia. Fish were acclimatized for 7 days in either normoxia (P(O(2)) approximately 150 Torr) or hypoxia (P(O(2)) approximately 75 Torr). After acclimatization, cardioventilatory, blood-gas and acid/base variables were measured during normoxia (P(O(2)) 148+/-1 Torr) then at two levels of acute (5 min) hypoxia, (P(O(2)) 72.6+/-1 and 50.4+/-0.4 Torr). Ventilation was significantly greater in hypoxic acclimatized fish as was the ventilatory sensitivity to hypoxia (Delta ventilation/Delta P(O(2))). The increase in ventilation and hypoxic sensitivity was due to increases in opercular pressure amplitude, gill ventilation frequency did not change. Heart rate was greater in hypoxic acclimatized fish but decreased in both acclimatization groups in response to acute hypoxia. Heart rate sensitivity to hypoxia (Delta heart rate/Delta P(O(2))) was not affected by hypoxic acclimatization. The ventilatory effects of hypoxic acclimatization can be explained by increased sensitivity to oxygen but the effects on heart rate cannot.     

Chemical lesions of the nucleus isthmi increase the hypoxic and hypercarbic drive to breathing of toads

The nucleus isthmi (NI) is a mesencephalic structure of the amphibian brain that has recently been reported to participate in the hypoxic and hypercarbic drive to breathing. However, previous studies used electrolytic and kainic lesions, which causes diffuse and nonspecific destruction. Thus, in the present study, we assessed the participation of NI in the respiratory response to hypoxia and hypercarbia using lesions produced with ibotenic acid (a substance that selectively destroys cell bodies but spares fibers of passage) into the NI of toads (Bufo paracnemis). Our results demonstrated that, under resting breathing, NI plays no role in pulmonary ventilation. Hypoxia and hypercarbia caused hyperventilation in all groups. Chemical lesions in the NI elicited an increase in ventilatory response to hypoxia and hypercarbia, due to a higher tidal volume. We conclude that NI cell bodies do not participate in the control of pulmonary ventilation under resting conditions, but exert an inhibitory modulation of hypoxic and hypercarbic drive to breathing, acting on tidal volume.     

CO2 retention in lung disease; could there be a pre-existing difference in respiratory physiology

Some patients with lung disease retain CO₂, while others with similar lung function do not. This could be explained if CO₂ retainers had a pre-existing low hypercapnic ventilatory response (HCVR) and, from this, a tendency to retain CO₂. To test if such a phenomenon exists in healthy people, we determined the change in end-tidal P_CO2 (ΔPET_CO2) produced by the addition of a dead-space (DS), during wakefulness and sleep, and related this to the HCVR measured awake. The group mean (n=14) HCVR slope was 2.2±1.1 (S.D.) L min⁻¹ mmHg⁻¹. The ΔPET_CO2 with the application of DS was 1.6±1.6 mmHg awake and 2.6±2.2 mmHg asleep. During wakefulness the ?PET_CO2 with DS did not correlate with the HCVR slope. However, during sleep, four subjects had a marked increase in the ΔPET_CO2 (3.7, 4.3, 6.2, 8.0 mmHg) and a relatively low HCVR (slope 1.5, 1.7, 1.5, 1.7 L min⁻¹ mmHg⁻¹, respectively). We speculate that such individuals, should they develop lung disease, may be predisposed to retain CO₂.     

Use of a highly sensitive electrophoresis-precipitation method to detect virus hepatitis B antigen in human blood serum

A modification of the highly sensitive method of electrophoresis-precipitation in polyacrylamide gel for the detection of virus hepatitis B antigen (HBsAg) and antibodies against it is described. The method completely preserves the specificity of immunodiffusion in gel, but is 1000–2000 times more sensitive for the detection of HBsAg. The method has given good results with the sera of patients with various diseases. It detects HBsAg more efficiently than other methods used previously.Scientific Experimental-Production Group, Laboratory of Cellular Immunity, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR O. V. Baroyan.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 508–509, April, 1977.     

Transplantation of human fetal tissue in hematology

Intravenous transplantation of human fetal tissue, notably of the liver and thymus, is used in emergency hematological states: aplastic anemia and acute leukemia. The strong manifestation of “graft-versus-host” disease proved unexpected. Fetal donor hepatic cells stimulate hemopoiesis in the recipient. In some cases true cellular chimerism has been observed, specifically when a transplant of human fetal tissue (THFT) to a fetus with prenatal pathology was performedin utero. In gene therapy attempts have been made to infuse hemopoietic stem cells intravenously or to introduce the adenosine aminase gene into leukocytes of patients with a deficiency of this enzyme. Treatment using transplantation of human fetal tissue will help solve the problem of HLA-histocompatibility and will make gene therapy more widely applicable. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 117, N ^o 4, pp. 375–377, April, 1994     

Increased load on the respiratory muscles in obstructive sleep apnea

We wished to quantify, in patients with obstructive sleep apnoea (OSA), the activity of the respiratory muscles in relation to upper airway occlusion and patency in sleep. We hypothesized that particular levels of neuromuscular activation are directly associated with upper airway patency. 21 patients with previously diagnosed OSA and 21 healthy control subjects underwent respiratory muscle testing and polysomnography. Neural respiratory drive, as measured by the electromyogram of the diaphragm (EMG_di) was elevated in the obese OSA patients, awake and supine (13.1(5.6)%max), compared to normal subjects (mean (SD) 8.1(2.3)%max, p < 0.01). During unobstructed breathing in sleep (stage N2) normal subjects had an EMG_di of 7.7(3.9) compared to 22.8(19.2)%max in the OSA group (p < 0.001). Prior to airway occlusion, EMG_{submandibular} and EMG_di dropped markedly, and then, following occlusion, increased progressively to their highest levels at airflow onset. Patients with OSA require specific and increased levels of neural respiratory drive to sustain ventilation in sleep.     

Immunosuppressive activity in human embryo growth media is associated with successful pregnancy: Effect of gonadotropin releasing hormone agonist (GnRHa) treatment of patients undergoingin vitro fertilization and embryo transfer (IVF-ET)

The aim of the present study was to determine whether the secretion of embryo-associated immunosuppressor factor (EASF) by preimplantation embryo correlates with pregnancy outcome and whether this relationship is influenced by pretreatment of gonadotropin releasing hormone agonist (GnRHa) in patients undergoingin vitro fertilization and embryo transfer (IVF-ET). EASF activity was measured using concanavalin A-induced human lymphocyte proliferation assay in 256 embryo growth media obtained from 61 patients undergoing IVF-ET. EASF activity was then correlated with GnRHa treatment and pregnancy outcome in these IVF patients. Results indicate that (i) the presence of immunosuppressive activity in human embryo growth media is associated with success of pregnancy in GnRHa nontreated patients and (ii) serum factors present in GnRHa-treated patients may affect the EASF secretion by preembryosin vitro.     

Isolation and immunochemical analysis of hydrolysis products of γG-globulin in the serum of partially hepatectomized rabbits

A fragment of the IgG molecule related to Fab was discovered in the serum of partially hepatectomized rabbits by immunochemical analysis. Subsequent fractionation of the serum on carboxymethylcellulose, with the use of an immuno-sorbent, led to the isolation of this fragment in a purified form. Its sedimentation constant was found to be 5.2S. It thus corresponds to a bivalent IgG fragment. If partial hepatectomy was performed on animals receiving trasylol, a polyvalent proteinase inhibitor, before the operation and during the next 4 h, the presence of the Fab fragment could not be demonstrated. It is concluded that the Fab fragment appears as a result of hydrolysis of IgG by tissue proteases liberated from the liver cells damaged during operation.Kursk Medical Institute, N. F. Gamaleya Institute of Epidemiology and Microbiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR G. V. Vygodchikov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 328–330, March, 1976.     

Proliferative activity of the developing seminiferous epithelium during prespermatogenesis in the golden hamster testis measured by bromodeoxyuridine labeling

Bromodeoxyuridine (BrdU)-labeling was used to study the cell kinetics of the developing seminiferous epithelium in the testes of golden hamsters aged 10.5 to 27.5 days post conception (dpc), i.e., during a period beginning one developmental day before testicular differentiation (11.5 dpc) and extending to the appearance of the first mature spermatogonia. Supporting (Sertoli) cells continuously proliferate throughout the period studied. Labeling indices amount to about 30% between the 10.5th and 16.5th dpc, and subsequently decrease to levels below 10% on the 26.5th and 27.5th dpc. Germ cells (prespermatogonia) proliferate between the 10.5th and 15.5th dpc and again, after a period of mitotic quiescence, from the 24.5th dpc onwards. This pattern of prespermatogonial proliferation substantiates and further specifies the successive appearance of M-prespermatogonia (10.5th to 15.5th dpc: proliferating), T ₁-prespermatogonia (16.5th to 23.5th dpc: quiescent), and T ₂-prespermatogonia (24.5th to 27.5th dpc: proliferating). Thus, the M-prespermatogonial phase of germ cell proliferation is shown to commence at least 24 h before testicular differentiation. Transitions from M- to T ₁-phase and from T ₁-to T ₂-phase are rather abrupt. Both the latter observation and the comparison with oogonial development in the female at the corresponding time (onset of meiosis) indicate the presence of an underlying control mechanism operative during prespermatogenic development. Due to different nuclear staining patterns, the BrdU-labeling method allows temporal subdivision of the S-phase, thus opening up prospects of more detailed cell-kinetic analyses of the seminiferous epithelium.     

Detection of cytomegalovirus DNA, viral antigens, and antibodies to it in patients after organ transplantation

Cytomegalovirus (CMV) DNA was determined by the PCR method, anti-CMV IgM and IgG were analyzed by enzyme immunoassay, and infective activity of CMV was evaluated by the rapid culture technique with monoclonal antibodies in the blood of patients, who underwent organ transplantation. In cases when the results coincided, PCR was much more sensitive, while the rapid culture technique was more reliable in predicting the course and outcome of CMV disease. Enzyme immunoassay failed to detect active infection by the moment of examination. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 5, pp. 560–563, May, 1999     

Improved aorto-ventricular matching in ischemic dilated cardiomyopathy patients after surgical ventricular restoration

Scope

This paper contains (i) derivation of the aorto-ventricular matching (AVM) index in terms of the ratio of aortic elastance and LV end-systolic elastance, E_aorta/E_es; (ii) procedure for determination of this index, by means of non-invasive measurements of auscultatory pressures, time-variation of blood volume ejected into the aorta, stroke volume and ejection fraction; (iii) results of improved AVM index evaluation in ischemic dilated cardiomyopathy (IDCM) patients following surgical ventricular restoration (SVR), as a result of reduced end-diastolic and end-systolic LV volumes and increased LV E_es.

Methodology

Among the ten recruited IDCM patients, four of them underwent surgical ventricular restoration (SVR) and coronary artery bypass graft (CABG), while six of them underwent CABG alone. All patients were studied by echocardiography pre- and 4 months post-operatively; LV volumes were determined by echo Doppler. LV end-systolic elastance E_es was determined from a derived expression, by employing blood pressure, stroke volume, ejection fraction, pre-ejection and systolic periods, and estimated normalized ventricular elastance at end-diastole, based on single-beat measurements. Aortic elastance E_aorta was determined by means of our modified single-beat method for determining aortic pressure profile.

Results

In the CABG plus SVR group, the AVM index E_aorta/E_es was reduced by 35% from 0.93 ± 0.32 to 0.60 ± 0.33, consistent with improved aorto-ventricular matching. However, in the CABG alone group, the AVM index E_aorta/E_es decreased only 11% from 1.02 ± 0.24 to 0.91 ± 0.29.

Conclusion

There is shown to be increased value of LV E_es and a more favorable decreased value of AVM index in those IDCM patients who underwent SVR.     

Structure of the corpuscles of Stannius in the euryhaline teleost Takifugu niphobles (Tetraodontiformes, Teleostei), with special regard to vascularization and extravascular channel system

Summary Vascularization and the extravascular channel system of the corpuscles of Stannius in a euryhaline teleost, Takifugu niphobles, were studied by scanning electron microscopy of the vascular corrosion cast, and histochemistry of exogenously injected horseradish peroxidase as a macromolecular tracer. The corpuscles were apposed to the caudal part of the ureter, away from the mesonephric kidney, and were supplied with arterioles from the genital artery running ventrally as a ramus of the dorsal aorta. Elaborate capillary networks irrigating the glandular lobules were collected by the venules to drain into the posterior cardinal veins. Electron microscopic examination of the glands demonstrated two types of secretory cells, type-1 cells with large granules, and type-2 cells with smaller granules. The type-1 cells, predominating in the gland, occasionally showed exocytosis of the secretory granules, mainly into intercellular spaces between adjoining cells. Exocytosis was also evident in the type-2 cells. The tracer molecule injected was visualized histochemically within the capillary lumina and intercellular spaces throughout the gland. The labelled spaces intercommunicated with each other to form an extensive extravascular channel system as a diffusing pathway within the gland. The possible role of this system in hormone transport and/or storage was discussed.This paper is dedicated to the 60th anniversary of Professor Yoshiharu Honma, Director of Sado Marine Biological Station of Niigata University     

F18 fluorodeoxyglucose uptake in progressive transformation of germinal centres

FDG-PET/CT is a widely established imaging modality for staging, restaging and monitoring therapy response in lymphoma patients. Progressive transformation of germinal centres (PTGC) is a benign condition presenting characteristically as asymptomatic lymphadenopathy. This paper presents a case of a 53-year-old man with a history of Hodgkin's disease (HD) whose F(18) FDG-PET/CT scan showed high uptake in left axillary lymph nodes (SUV 3.8). A subsequent, left axillary lymph node biopsy revealed PTGC. PTGC can present as a false positive finding on FDG-PET/CT in lymphoma patients and biopsy should be done in HD patients in clinical remission but have a positive FDG-PET/CT scan.