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Biomedical subjects

C Jordan

Publications and source records attributed to C Jordan.

At least 19 recordsLinked to original sources
PubMed1992

Somatosensory and auditory evoked responses recorded simultaneously: differential effects of nitrous oxide and isoflurane.

Auditory (AER) and somatosensory evoked responses (SSER) were recorded simultaneously in eight patients under anaesthesia before surgery. We studied the effects of equi-MAC end-expiratory concentrations of isoflurane (0.65-0.75%) and nitrous oxide (60-65%). The anaesthetics were changed at random in three consecutive 10-min periods so that each patient received both drugs. From the AER recorded from the vertex and inion, Pa and Nb latency and amplitude were measured. N13, P20 latency and N13 amplitude were measured from SSER recordings from the neck and P15, N20, P25, N35, P45 latency and P15-N20, N20-P25, P25-N35 and N35-P45 amplitude from the scalp over the hand area of the sensory cortex. Compared with nitrous oxide, isoflurane significantly increased the latencies of the AER waves Pa (P = 0.02) and Nb (P = 0.02), and the SSER waves N20 (P = 0.001) and P25 (P = 0.04). We were unable to demonstrate significant differences in Pa and Nb amplitude between isoflurane and nitrous oxide that we had seen previously. However, the amplitude of the SSER wave N20 was reduced significantly by nitrous oxide compared with isoflurane (P = 0.0004). This wave (N20) is thought to emanate from the thalamo-cortical radiations, and our findings may be explained by an analgesic effect of nitrous oxide mediated by endogenous opioids.

Adult↗
PubMed1992

Auditory evoked response and awareness: a study in volunteers at sub-MAC concentrations of isoflurane.

We have investigated the relationship between the auditory evoked response (AER) and simple tests of conscious awareness at four end-expiratory concentrations (0.0, 0.1, 0.2 and 0.4 MAC) of isoflurane in oxygen in each of eight anaesthetist volunteers, in random order, at least 1 week apart. The early cortical AER was recorded from electrodes at the vertex and inion. Amplitudes of the waves Pa, Nb and Pc and latencies of the waves Na, Pa, Nb, Pb and Nc were measured. All the AER variables were highly significantly related to end-expiratory anaesthetic concentration. Amplitudes decreased and latencies increased progressively with increasing anaesthetic concentration. The AER variables were also highly significantly related to the level of response. Amplitudes were greatest and the latencies shortest when there was full response to command. (Nb latency increased from 47.5 to 54.5 ms between partial and no response.) The close correlation between the effects of concentration and level of response, and between concentration and the AER implied that it was difficult to demonstrate those changes in the AER which specifically relate to changes in response. At 0.2 MAC, however, which was the concentration at which all subjects showed some deficit, the response to a shock word was distinguished clearly by Nb latency. In eight of 24 possible comparisons (eight AER variables and three types of psychological test) the AER fitted the response more closely than concentration.

Awareness↗
PubMed1992

Age-related asymmetry on a cued-listening task.

We report results on a cued-listening task designed to simulate the listening problems commonly described by individuals with sensorineural hearing loss, especially those experienced by elderly persons. Against a background of multitalker babble, the subject detected targets embedded in continuous discourse. Noncoherent segments of this discourse were presented simultaneously from loudspeakers on the right and left sides. A signal light cued the side to be monitored during a listening trial. The overall difficulty of the task was manipulated by variation of the message to competition intensity ratio. A sequence of listening trials, half-cued to the right side, half cued to the left side, was executed at each of four message to competition intensity ratios. Nineteen young adults with normal hearing and 28 elderly persons with presbyacusic hearing loss were evaluated. All subjects, young and elderly, were able to complete the cued-listening task successfully. Results showed a small but significant right-side advantage in the young group and a substantial right-side advantage in the elderly group. The application of the testing technique to the evaluation of hearing aid performance is illustrated in two elderly persons.

Adult↗
PubMed1992

Acoustic reflex abnormalities in cranial-cervical dystonia.

Previous anatomic and physiologic studies suggest brainstem dysfunction in cranial-cervical dystonia. To further explore this, we studied suprathreshold acoustic reflex waveforms in 15 such patients. A unique feature of this technique is its ability to reject movement artifacts before averaging the acoustic reflex waveforms. Thirteen patients (87%) showed some abnormality in reflex waveform morphology. There were both amplitude and latency abnormalities. These findings support the hypothesis that cranial-cervical dystonia reflects dysfunction of the brainstem.

Acoustic Stimulation↗
PubMed1992

Hairy cell leukemia and autoimmune hemolytic anemia.

A case of hairy cell leukemia (HCL) presenting as autoimmune hemolytic anemia (AHA) is described. A 40-year-old woman presented with severe hemolytic anemia. The morphological and immunological studies of bone marrow and spleen revealed a hairy cell leukemia. Although autoimmune diseases are a well known complication of HCL this is the first description of AHA as a complication of HCL.

Adult↗
PubMed1990

Memory deficits in workers suffering from hard metal disease.

This study examined memory functioning on the Wechsler Memory Scale-Revised in a group of adult tungsten carbide workers with hard metal disease and a group of matched controls. The hard-metal-exposed group of workers showed memory deficits related to difficulties in attention and verbal memory, with an apparent sparing of visual-spatial memory. Implications of this finding for future research are discussed.

Cobalt↗
PubMed1989

Anti-mouse IgM immunoglobulin protects weanling mice from Coxsackievirus infection.

Mice treated from birth with rabbit anti-mouse IgM antiserum (anti-mu), although immunosuppressed in regard to B cell function, may paradoxically be protected when challenged with certain viruses. Our early studies indicated that short term treatment of weanling mice protected against Semliki forest virus, herpes simplex virus, and Coxsackievirus B1. For this study, the murine model of Coxsackievirus B1 infection was chosen to determine if specific anti-mu immunoglobulin (anti-mu Ig) would protect and whether protection could be correlated with antiviral activity in certain organs. Weanling Balb/c mice were treated intraperitoneally (i.p.) with either affinity purified anti-mu Ig or purified normal rabbit (NR) Ig two consecutive days prior to i.p. challenge with Coxsackievirus B1. Mortality of anti-mu Ig treated mice was significantly lower than controls (3.4% vs 89%, P less than 0.001). Importantly, this purified anti-mu-induced protection correlated well with reduced levels of virus in blood and certain organs, especially brain. This decrease was not attributed to interferon (IFN) or virus-specific neutralizing (NT) antibody or enhanced cellular cytotoxicity. Anti-mu treatment appears to inhibit virus replication and/or enhance clearance of virus from target organs. The data indicate that a unique antiviral activity is activated by anti-mu treatment, and can be passively transferred to and protect recipient mice. The murine model of Coxsackievirus disease appears to be well suited for use in the elucidation of the mechanism of this protection.

Animals↗
PubMed1989

In vitro galactosylation of a 110-kDa glycoprotein by an endogenous cell surface galactosyltransferase correlates with the invasiveness of adrenal carcinoma cells.

We have examined the role of a cell surface galactosyltransferase, laminin, and laminin-binding protein (receptor) in the invasion of clonal derivatives of a murine adrenal carcinoma cell line. Although a 10-fold variation was found in the ability to invade a reconstituted basement membrane matrix, levels of intracellular laminin and the laminin-binding protein were shown to be present and secreted equally in all lines. Of the eight lines tested, seven showed a correlation between invasion and the incorporation of [3H]galactose from UDP-[3H]galactose into a 90- to 110-kDa protein. One noninvasive line (clone HSR), however, retained high galactosyltransferase activity yet could not galactosylate the endogenous 90- to 110-kDa substrate. Interestingly, this clone was unable to attach to laminin. Although high galactosyltransferase activity can be consistent with cells of high invasiveness, our results suggest that the galactosylation status of a 90- to 110-kDa Y1 cell surface glycoprotein is most indicative of invasion potential.

Adrenal Gland Neoplasms↗
PubMed1989

In situ hybridization analysis of myelin gene transcripts in developing mouse spinal cord.

We analyzed the location and abundance of transcripts for the 4 CNS myelin protein genes, myelin basic protein (MBP), proteolipid protein (PLP), myelin-associated glycoprotein (MAG), and 2',3'-cyclic nucleotide phosphohydrolase (CNP), in the mouse cervical spinal cord from the time of rapid myelination until adulthood (8-45 d). In the white matter, maximal levels of transcripts were found for each of the myelin genes at the peak of myelination (8 d). Total MBP and PLP mRNAs stayed high until 20 d and showed a minor decrease thereafter. In contrast, MAG and the MBP exon 2 containing transcripts (coding for the 21.5 and 17 kDa MBP isoforms) decreased sharply between 8 and 20 d, suggesting that high levels of these transcripts are needed primarily during the initiation of myelination. CNP transcripts were less abundant, maintained high expression until 20 d, and then decreased sharply. PLP, MAG, and CNP transcripts were clustered in the oligodendrocyte cell body, while MBP mRNAs were scattered throughout the cell body and processes. In contrast to the white matter, all these myelin specific transcripts in the gray matter showed a marked increase from 8 to 20 d, as did the number of oligodendrocytes identified by CNP immunostaining. MAG transcripts were found in white matter and in satellite and other oligodendrocytes of the gray matter but not in neurons identified by their expression of neurofilament transcripts. The results of our quantitative in situ hybridization study are in good agreement with those of previous molecular studies and provide new information on the cellular and topographic distribution of myelin-specific mRNAs during myelination.

Animals↗
PubMed1989

Rehabilitation of the mastectomy patient: a randomized, blind, prospective study.

After biopsy confirmation of breast carcinoma, women who were scheduled to undergo a modified radical mastectomy had demographic data collected, goniometric measurements of shoulder flexion and abduction, and functional evaluation of the ipsilateral shoulder performed, and upper extremity circumferential measurements at five levels determined. Patients were then randomly assigned either to a group that received immediate postoperative physical therapy or to one that did not. Results represent the combination of data from a pilot study and this subsequent study following appropriate statistical analysis. Sixty-four women in the treatment group showed a statistically significant increase in shoulder range of motion in both abduction and flexion as compared to 51 women who received no physical therapy. The treated group also had fewer problems with five of the six upper extremity functional tasks that were assessed. There were no significant differences between the groups for length of hospital stay, postoperative complications, or upper extremity edema. The authors conclude that early physical therapy intervention makes a significant contribution to return to normal function without increasing the incidence of postoperative complications or prolonging hospital stay.

Activities of Daily Living↗
PubMed1988

Effect of surgical stimulation on the auditory evoked response.

Previous studies have shown a dose-related effect of a number of general anaesthetic agents on the early cortical waves in the auditory evoked response (AER). In this study the effect of surgical stimulation on these waves was examined in 11 patients anaesthetized with thiopentone, nitrous oxide and halothane and paralysed with pancuronium. The inspired nitrous oxide concentration and end-tidal halothane concentration were held constant at 70% and 0.3%, respectively, and baseline AER recordings were made. Following surgical stimulation there was a progressive and significant increase in the amplitude of waves Nb and Pb/Pc. Unambiguous autonomic responses were seen in three patients, but these were not significantly correlated with changes in the AER. We conclude from this, and previous studies, that the amplitude of cortical waves in the AER are sensitive not only to anaesthetic concentration but also to surgical stimulation. The AER may, therefore, provide a useful index of depth of anaesthesia, that is the balance between the effects of surgical stimulation and anaesthetic depression on central nervous system activity.

Adult↗
PubMed1988

Antagonism of morphine-induced respiratory depression with nalmefene.

The duration of respiratory depression induced by morphine 10 mg/70 kg was studied following the administration of one of two opioid antagonists. Respiratory measurements included: (i) the ventilatory response to carbon dioxide, described in two ways--the minute ventilation at an end-tidal carbon dioxide partial pressure of 8 kPa (VE8) and the log slope of the ventilatory response to carbon dioxide; (ii) resting end-tidal carbon dioxide partial pressure; (iii) rate of ventilation. One hour after administration of morphine, one of the following was given i.v.: nalmefene 0.4 mg/70 kg; naloxone 0.4 mg/70 kg (low dose); naloxone 1.6 mg/70 kg (high dose); or saline placebo. The depression of VE8 by morphine was antagonized by all three treatments for the 1.5 h after the injection. However, for the 1.5-6 h after antagonist, VE8 following naloxone became depressed, whereas VE8 after nalmefene remained significantly increased compared with other treatments. Nalmefene restored the slope of the ventilatory response to baseline for 6 h and differed significantly from low but not high dose naloxone. Resting end-tidal carbon dioxide measurements demonstrated that nalmefene activity exceeded that of low but not high dose naloxone over the 1.5-4.5 h period. Rate of ventilation was not different between treatments.

Adult↗
PubMed1988

Influence of acute isocapnic hypoxia on bronchial calibre and "expiratory reserve" volume in dogs.

The effects of hypoxia on bronchial calibre were investigated in anaesthetized dogs using a computer-aided forced airflow oscillation technique which derived specific lower airways conductance (sGlaw) and "expiratory reserve volume" (ERV). Measurements were made with inspired oxygen concentrations varying from 40% to 10%. sGlaw tended to be slightly reduced (indicating bronchoconstriction) by decreasing the oxygen concentration from 40% to 15%, these changes being statistically significant after the administration of atropine. ERV was unaffected by changes in oxygen concentration from 40% to 15%, but was significantly reduced during ventilation with 10% oxygen. This effect was reversed by re-oxygenation and was not abolished by prior administration of atropine. It was concluded that both bronchoconstriction and changes in lung volume may be responsible for changes in airway resistance during hypoxia.

Airway Resistance↗
PubMed1988

Effects of xylazine and acepromazine on bronchomotor tone of anaesthetised ponies.

The effects of xylazine (an alpha 2-adrenoceptor agonist) and acepromazine (an alpha-adrenoceptor antagonist) on bronchomotor tone were investigated in seven anaesthetised, apnoeic ponies using a computer aided forced oscillation technique, which separates changes in bronchial calibre from changes in lung volume. Both agents produced bronchodilatation and a decrease in lung volume.

Acepromazine↗
PubMed1988

Current status of functional lower extremity surgery in adult spastic patients.

Ten percent of upper motor neuron spastic patients are candidates for functional surgery. If the main cause of the disability is abnormal muscle tone and not sensation, balance, cognition, or perceptual problems, good results from tendon lengthening or transfers are to be expected. The preoperative work-up should consist of examination, trial orthoses, nerve blocks, and most importantly dynamic electromyography. Releases or neurectomies are generally done in nonfunctional patients. Phenol blocks are a temporizing procedure during the phase of neurologic recovery. The patients all tolerated the anesthesia well, and the surgical risks are the same as in other lower extremity procedures.

Humans↗
PubMed1988

Group A streptococcal infection in children younger than three years of age.

We evaluated 758 sick children younger than 3 years of age for Group A beta-hemolytic streptococcal (GABHS) upper respiratory infection (URI) to determine the usual clinical presentation of the disease in this age group, indications for culture and the optimal site(s) from which to isolate the organism. GABHS infection was documented in 35 subjects (4.6%). The classic presentation (as proposed in the 1940s) of GABHS URI in children younger than 3 years of age was not confirmed by this study. In 32 of the GABHS cases there were pharyngitis, common cold symptoms or both, and these were associated with acute otitis media 10 times and with otitis media with effusion 3 times. Clinical impetigo was associated with GABHS URI (4 of 32 cases). GABHS URI would not have been documented in 6 of 32 cases if cultures of the anterior nares had not been performed. Children between 18 and 36 months of age were more likely to have GABHS disease than were younger children. Hoarseness and vomiting occurred less frequently in children younger than 36 months with GABHS infection than in those of that age who had non-beta-hemolytic streptococcal illnesses. A history of two or more siblings at home or a family member with a recent streptococcal infection and the presence of irritability, a reddened throat or palate or uvular edema were each associated with GABHS URI. We concluded that sick children between 18 and 36 months of age with a reddened throat should have cultures taken of the throat and anterior nares for GABHS.(ABSTRACT TRUNCATED AT 250 WORDS)

Bacteriological Techniques↗
PubMed1988

Hamstring release for knee flexion contracture in spastic adults.

Thirty adults (17 male and 13 female patients) with spastic disorders were treated by hamstring releases of 46 extremities. The diagnoses were stroke, traumatic brain injury, spinal cord injury, multiple sclerosis, and anoxia. The mean age at surgery was 38.6 years. Three extremities had partial release of the hamstring tendons behind the knee; the remaining 43 extremities had a complete release. The average position of the knee was 61.4 degrees of flexion preoperatively and 6 degrees postoperatively. The follow-up period averaged 21.3 months. Preoperatively, 87% of patients were nonambulatory. Following hamstring release 43% became ambulatory and 17% had gained the ability to transfer. Complications included two stroke patients with severe peripheral vascular disease; one developed a large nonhealing sore of the ankle and the other developed gangrene of the foot. Both patients required amputation. Three other patients developed recurrent flexion contractures that have since been rereleased with good results.

Adult↗