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Biomedical subjects

R Jung

Publications and source records attributed to R Jung.

At least 91 records · Page 5Linked to original sources
PubMed1991

Cardiorespiratory responses to glutamatergic antagonists in the caudal ventrolateral medulla of rats.

The role of caudal ventrolateral medullary (CVLM) depressor neurons in influencing arterial pressure and ventilation as well as the baroreflex control of arterial pressure was investigated, and the part played by excitatory N-methyl-D-aspartate (NMDA) and non-NMDA receptors in mediating the responses was determined. In urethane-anesthetized, spontaneously breathing rats unilateral microinjections into the caudal depressor area of the broad-band glutamatergic antagonist kynurenic acid (KYN, 5 nmol or 1.58 nmol), or NMDA antagonist 2-amino-5-phosphonovaleric acid (2-APV, 2.7 nmol), or the non-NMDA antagonist 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 0.257 nmol) caused a respiratory arrest within 4 min and the animals had to be artificially ventilated. Respiratory frequency increased on injecting KYN and CNQX while it did not change significantly with 2-APV. Apnea resulted from progressive decrease in tidal volume. During the apnea ventilation with 5% CO2 did not revive breathing. Mean arterial pressure (MAP) increased significantly with KYN and 2-APV injections but not with CNQX. The baroreflex decrease of MAP, elicited by left or right aortic depressor nerve stimulation, was significantly reduced or abolished after bilateral microinjections of all 3 antagonists. Ventilation as well as the baroreflex usually recovered after 1-1.5 h. Microinjections of the same doses of antagonists into the facial nucleus, as well as application of KYN (25 nmol) to the ventral medullary surface above the hypoglossal rootlets, had no significant effect. The results support previous findings that the CVLM neurons of the rat inhibit sympathetic neurons providing the vasomotor tone, and that an intact CVLM is obligatory for mediating the baroreflex decrease of arterial pressure. The results also indicate that: (1) the CVLM is essential for sustaining ventilation in the rat; (2) only NMDA receptors are involved in maintaining baseline blood pressure while both NMDA and non-NMDA receptors mediate the baroreceptor depressor reflex; and (3) both NMDA and non-NMDA receptor activation is necessary to sustain ventilation.

2-Amino-5-phosphonovalerate↗
PubMed1991

Changes of slow cortical negative DC-potentials during the acquisition of a complex finger motor task.

To study whether electrophysiological correlates of increasing motor skill can be demonstrated in man, we recorded cortical negative DC-potentials during the acquisition of a complex finger movement in 21 subjects. The movement consisted in moving a matchstick to and fro between the index finger (II) and the little finger (V). Cortical negative DC-potentials were recorded at Fz, Cz, C1, C2 and Pz. As a control a simple finger movement was performed during the same session by 7 of the Ss. Both tasks were repeated 60-80 times and averages of the first and the last 15 artifact-free single runs were compared. Whereas only a slight, inconstant decrease in surface electronegativity during the simple motor task was observed, a significant reduction in potential size occurred during the complex task at Cz (maximum), C1, C2 and Pz but not at Fz. In addition, a significant difference in the decrease of surface electronegativity between various electrode positions was observed. We suggest that these changes in potential size during the process of motor learning may reflect an altered cortical organisation of movement control during the acquisition of a complex motor task.

Adult↗
PubMed1991

Maleic acid dimethylester: evaluation of dermal toxicity and genotoxicity.

Maleic acid dimethylester (MAD) was investigated in acute and subacute dermal toxicity studies, for sensitization potential, and for in vivo and in vitro genotoxicity. The acute dermal toxicity in rats was low (LD50 greater than 2000 mg/kg body weight). Only local effects, erythema and necrosis, occurred at the site of application. Corresponding dose-related effects were observed in a 28-day repeated dermal toxicity study in rats. Treatment-related systemic alterations were observed in feed consumption, body weights, haematology and clinical chemistry at 170 and 500 mg MAD/kg body weight. Based on the results of this study, the no-toxic-effect level of MAD was considered to be 60 mg/kg body weight/day. However, slight dermal irritative effects were also present at the lowest dose level (60 mg/kg body weight). The primary skin irritation test in rabbits showed only slight erythema and oedema. The results of the maximization test in guinea-pigs indicated a clear sensitizing potential of MAD. In the Ames test, with five strains of Salmonella typhimurium, MAD was not mutagenic up to the highest dose level of 5000 micrograms/plate. In the micronucleus test, in which mice were given 1000 mg MAD/kg body weight by gavage the compound revealed no clastogenic effects.

Administration, Cutaneous↗
PubMed1991

Different legumin protein domains act as vacuolar targeting signals.

Legumin subunits are synthesized as precursor polypeptides and are transported into protein storage vacuoles in field bean cotyledons. We expressed a legumin subunit in yeast and found that in these cells it is also transported into the vacuoles. To elucidate vacuolar targeting information, we constructed gene fusions of different legumin propolypeptide segments with either yeast invertase or chloramphenicol acetyltransferase as reporters for analysis in yeast or plant cells, respectively. In yeast, increasing the length of the amino-terminal segment increased the portion of invertase directed to the vacuole. Only the complete legumin alpha chain (281 amino acids) directed over 90% to the vacuole. A short carboxy-terminal legumin segment (76 amino acids) fused to the carboxy terminus of invertase also efficiently targeted this fusion product to yeast vacuoles. With amino-terminal legumin-chloramphenicol acetyltransferase fusions expressed in tobacco seeds, efficient vacuolar targeting was obtained only with the complete alpha chain. We conclude that legumin contains multiple targeting information, probably formed by higher structures of relatively long peptide sequences.

Amino Acid Sequence↗
PubMed1990

Development of an in vitro analogue of initiated mouse epidermis to study tumor promoters and antipromoters.

To facilitate the study of skin tumor promotion, a cell culture model system with characteristics analogous to initiated mouse epidermis was established. Cells of the keratinocyte cell line 308, derived from adult mouse skin initiated with 7,12-dimethylbenz[a]anthracene, display the initiated phenotype, since papillomas are produced when the cells are grafted to the backs of athymic mice. Coculture of a small number of these initiated cells with confluent normal primary keratinocytes resulted in the inhibition of growth of colonies of 308 cells. Addition of fresh keratinocytes weekly was required to sustain the inhibition for 3-4 weeks. Inhibition of 308 cell colonies required culture medium with a calcium concentration of 1.2 mM; normal keratinocytes did not inhibit 308 cells in medium with 0.05 mM calcium. Growth of 308 cells was not inhibited by coculture with confluent fibroblasts or by 1.2 mM calcium medium conditioned by either keratinocytes or fibroblasts. During continuous exposure of the cocultures to tumor promoters, 308 cell colonies became apparent within 2-3 weeks. A limited number of promoters were tested in this model system and 12-O-tetradecanoylphorbol-13-acetate, 12-O-retinoylphorbol-13-acetate, mezerein, and benzoyl peroxide were all active. The number of colonies which developed during promoter exposure in cocultures showed a dose-response curve which differed from the dose-response curve for stimulation of growth of 308 colonies in the absence of normal keratinocytes. Simultaneous treatment with 12-O-tetradecanoylphorbol-13-acetate and known inhibitors of skin tumor promotion, such as retinoic acid, fluocinolone acetonide, and bryostatin 1, blocked colony formation of 308 cells in cocultures but not in cultures with only 308 cells. In this model system, the actions of promoters and inhibitors both appear to be mediated by normal keratinocytes.

9,10-Dimethyl-1,2-benzanthracene↗
PubMed1990

Isolation and characterization of HIV-2ben obtained from a patient with predominantly neurological defects.

A HIV-2 strain named HIV-2ben was isolated from peripheral blood lymphocytes of a patient who, since 1984, had developed neurological symptoms such as Raynaud's syndrome, followed by paresthesia of extremities and ataxia, and finally paraparesis of the legs and incontinence. This new isolate could be distinguished from HIV-2rod by antibody-binding epitopes, peptide maps of core p24 and p18 polypeptides and restriction endonuclease cleavage pattern.

Animals↗
PubMed1990

Cardiovascular and respiratory responses to slow ramp carotid sinus pressures in the dog.

The respiratory and mean arterial pressure (MAP) responses to slow ramp pressure stimulation of carotid baroreceptors were compared in pentobarbital-anesthetized vagotomized dogs breathing 100% O2. Carotid sinus pressure (CSP) was raised from 50 (control) to 220 mmHg and then returned to control as linear ramps (+/- 1 mmHg/s) in isolated sinuses. MAP, heart rate (HR), ventilation (VE), frequency (f), and tidal volume (VT) were expressed as percent of control. The maximum difference between responses to positive and negative ramps at a given CSP (MAX) and the average difference (AVG) served as indicators of the hysteresis for each response. In 27 dogs MAP changed monotonically with varying CSP with insignificant (P = 0.27, MAX) or barely significant (P = 0.03, AVG) hysteresis, monotonic function being one that is continuously nondecreasing or continuously nonincreasing. Similar responses were obtained for HR. VE decreased as CSP increased, but the change was not monotonic. During negative ramp, VE increased back to control with an overshoot. Hysteresis for VE was pronounced (P less than 0.0001, both measures). The VE response was primarily determined by f; VT increased with CSP. To eliminate secondary respiratory effects due to alterations in MAP, in seven dogs similar experiments were performed after ganglionic blockade with hexamethonium. Hysteresis in VE and f persisted. To assess the role of changing arterial PCO2 (PaCO2) on VE, the CSP was held constant (after a ramp rise) at 140, 150, or 180 mmHg before reducing it at -1 mmHg/s to 50 mmHg; however, a significant hysteresis in VE was still observed. Further experiments, to eliminate secondary reflexes due to altered PaCO2, were performed in seven dogs after ganglionic blockade and paralysis with Flaxedil, with phrenic nerve activity as an indicator of ("neural") respiration. The hysteresis in VE and f were no longer significant. In summary, the results indicate that 1) slow ramp carotid baroreceptor stimulation elicits both VE and cardiovascular responses, the VE response showing a dramatically higher hysteresis than the cardiovascular responses; 2) the ventilatory hysteresis is partially explained by the secondary changes in PaCO2 and perhaps by cardiovascular variables; and 3) the central processing of the baroventilatory reflex appears to be rate sensitive at a slower rate of pressure change than that which causes rate sensitivity in the baropressure reflex.

Animals↗
PubMed1990

Cerebrospinal fluid pressure in patients with brain tumors: impact of fentanyl versus alfentanil during nitrous oxide-oxygen anesthesia.

The effects on the cerebrospinal fluid pressure (CSFP) of alfentanil and fentanyl were compared during nitrous oxide-oxygen (N2O-O2) anesthesia in 24 patients who had brain tumors. Monitored variables included CSFP (lumbar subarachnoid catheter), heart rate from electrocardiographic lead II, mean radial arterial blood pressure, and arterial blood gas tensions. General anesthesia was induced with thiopental, 5 mg/kg IV in divided doses, and maintained with 70% N2O in O2; ventilation was held constant (PaCO2 = 37.4 +/- 1.6 mm Hg [mean +/- SEM]). After baseline data were recorded, 16 subjects were randomly assigned to receive either 5 micrograms/kg fentanyl as an intravenous bolus or 50 micrograms/kg alfentanil as an intravenous bolus, followed by an infusion of alfentanil at 1 micrograms.kg-1.min-1. Monitored variables were continuously recorded for 15 min after opioid injection. A third group of 8 patients was studied subsequently; they received only N2O-O2 during a 15-min observation period and served as controls. Blood pressure was held constant with an intravenous infusion of 0.1% phenylephrine, as needed; noxious stimulation was carefully avoided. Cerebrospinal fluid pressure remained unchanged both in patients who received N2O-O2 alone and in those who received fentanyl-N2O-O2. By contrast, those who received alfentanil-N2O-O2 had a gradual increase in CSFP, reaching 30% above baseline values after 10 min and stabilizing thereafter. Although the absolute increase in CSFP during normocarbic alfentanil-N2O anesthesia was relatively small (9.5 +/- 1.3 mm Hg to 13.0 +/- 1.3 mm Hg [mean +/- SE], P less than 0.05), the absence of a similar effect after fentanyl administration suggests that precautionary measures such as hyperventilation are advisable if alfentanil is used for potentiating normocarbic N2O-O2 anesthesia in neurosurgical patients with intracranial mass lesions.

Adult↗
PubMed1989

Tonic and baroreflex effects on arterial pressure and ventilation of pentobarbital and nicotine on the rat ventral medullary surface.

Unilateral aortic depressor nerve stimulation caused depression of arterial pressure (baropressure reflex) and ventilation (baro-ventilatory reflex) in urethane-anesthetized, spontaneously breathing Sprague-Dawley rats. Application of sodium pentobarbital to the ventral medullary surface (VMS) depressed baseline arterial pressure and ventilation, and attenuated the baro-pressure reflex, but not the baro-ventilatory reflex. Application of nicotine on the VMS decreased baseline arterial pressure and increased ventilation, but left both baro-pressure and baro-ventilatory reflexes unaltered. The results suggest that some of the structures that affect vasomotor tone may not be involved in the baroreflex inhibition of arterial pressure. Additionally, neither the neural structures near the VMS which modulate CO2 control of ventilation, nor those that affect tonic control of vasomotor tone are likely to be significantly involved in the baro-ventilatory reflex.

Animals↗
PubMed1989

Pharmacokinetics of triamterene in geriatric patients--influence of piretanide and hydrochlorothiazide.

Pharmacokinetics of triamterene (single oral dose of 50 mg) and its pharmacologically active metabolite (OH-TA-ester) were determined in 20 geriatric patients with multiple diseases. Mean peak concentration of triamterene was increased in the elderly patients compared with the data of young healthy volunteers. Coadministration of piretanide seems to lower the mean plasma concentration (AUC) and the mean concentration after 24 h of triamterene as compared with the coadministration of hydrochlorothiazide.

Aged↗
PubMed1989

The prevalence and management of pain in patients with AIDS: a review of 134 cases.

In light of the lack of any prior systematic evaluations of the prevalence and types of pain syndromes and treatments found in patients with AIDS, a chart review study was undertaken to evaluate this issue. Fifty-two of 96 charts reviewed (54%) had at least one note on nonprocedural pain or analgesic prescription. Although chest pain was the most prevalent pain location (22%), presumably because of the high incidence of Pneumocystis carinii pneumonia, other possible AIDS-related entities, such as peripheral neuropathy and thrombophlebitis, were also found. No specific AIDS syndromes could be identified that were related to a higher incidence of pain. Nearly one-third of patients with pain received codeine (31%), others received acetaminophen (27%), and 17% of patients received acetaminophen and oxycodone HCl. Specific pain management interventions must be evaluated and applied to control the nontrivial occurrence of pain in patients who have AIDS symptoms that may be overlooked by the physician given the overwhelming disease process.

Acquired Immunodeficiency Syndrome↗
PubMed1989

Premotor programming and cortical processing in the cerebral cortex. Electrophysiological correlates of hemispheric dominance.

Slow brain potentials were averaged from 12-15 EEG records (t = DC or 5 s) before and during voluntary hand movements and writing, spatial vision, language, and calculation tasks without vocalization and with visual fixation. EOG and writing pressure or EMG were recorded simultaneously. Skilled actions caused largest negative potentials in the contralateral sensorimotor hand area. Left-sided lateralization or bilaterally equal surface-negative potential shifts appeared during language and calculation tasks in 90% of the right-handers and in 75% of the left-handers. Right-sided lateralizations occurred during the viewing of perspective Necker figures or random-dot stereograms in the large majority of all subjects.

Adolescent↗
PubMed1987

Elevated pulmonary capillary wedge pressure in a patient with hypovolemia.

Since its introduction in 1969, the balloon-tipped pulmonary artery catheter has become widely accepted. Pulmonary capillary wedge pressures have been used diagnostically to determine left ventricular preload and volume status. We report on a patient with noncardiogenic pulmonary edema, secondary to a heroin overdose, who was hypovolemic and had an elevated pulmonary capillary wedge pressure. We discuss possible explanations and present evidence that the pulmonary capillary wedge pressure does not always accurately reflect volume status.

Adult↗