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A Rees

Publications and source records attributed to A Rees.

At least 37 records · Page 2Linked to original sources
PubMed1997

Regularity of firing of neurons in the inferior colliculus.

The spike discharge regularity of 254 tonically firing units in the inferior colliculus (IC) of the anesthetized guinea pig was studied in response to tones presented at best frequency (BF) to the ear contralateral to the recorded IC. Regularity of firing was measured by calculating the coefficient of variation (CV) as a function of time over the course of a unit's response. Two hundred and fifteen units (56 under urethan and 159 under chloralose anesthesia) in the central nucleus of the IC (CNIC) were studied in detail. In response to tones at 15-25 dB above threshold, 80% of units in the urethan sample fired regularly (CV < 0.5) during their sustained response, and 46% were highly regular (CV < or = 0.35). For chloralose the values were 68% and 23%, respectively. Units recorded under urethan were significantly more regular than those recorded under chloralose. For units in the sample with a measurable onset CV, 63% were regular and 44% highly regular under urethan, and 73% were regular and 54% highly regular under chloralose. The units' peristimulus time histogram (PSTH) patterns were classified into subdivisions of four categories: choppers [9%: chop-sustained (Cs), chop-onset (Co)]; pausers [42%: pauser-chop-sustained (P/Cs), pauser-chop-onset (P/Co), pauser-no-chop]; ON-sustained (43%: primary-type, L-type, h-type); and sustained (6%). The presence of chopping was a reliable predictor of regularity: Cs and P/Cs units were highly regular throughout their response, whereas Co and P/Co units were highly regular at onset and became less regular. Some units in the other PSTH categories were highly regular despite the absence of chopping, and units with virtually identical PSTHs showed very different sustained CVs. Regularity was measured as a function of firing rate in 71 units. In 23%, regularity remained constant when firing rate changed with stimulus level. Forty-six percent fired more regularly as firing rate increased, 8% fired less regularly, and 23% of units showed no consistent relationship between CV and firing rate. Regularity did not correlate with the neurons' frequency response areas or BFs. Regular firing was also found in a smaller sample of units recorded in cortices surrounding the CNIC. We conclude that regular firing is a characteristic feature of most neurons in the IC. Regularity is a specific feature correlated with four PSTH types (Cs, Co, P/Cs, and P/Co). Other PSTH types may or may not exhibit regularity.

Animals↗
PubMed1997

Reduced frequency of severe hypoglycemia and coma in well-controlled IDDM patients treated with insulin lispro. The Benelux-UK Insulin Lispro Study Group.

OBJECTIVE: Several studies have suggested that use of the short-acting insulin analog, insulin lispro, in multiple injection therapy may reduce the risk of hypoglycemia in comparison with regular insulin. This effect might be more pronounced in well-controlled patients, since intensive treatment of IDDM increases the rate of severe hypoglycemic events. This study evaluated the effects of insulin lispro on glycemic control and hypoglycemia rates in well-controlled IDDM patients. RESEARCH DESIGN AND METHODS: This was an open, randomized, 6-month crossover study of 199 IDDM patients. Glycemic control was evaluated by HbA1c, home blood glucose measurements, and rate and timing of hypoglycemic events. At the end of the study, patients completed an evaluation form regarding therapy-related quality of life. RESULTS: HbA1c remained constant at approximately 7.3% throughout the study. Meal-related glucose excursions were significantly lower with insulin lispro compared with regular insulin (mean -0.8 +/- 1.7 vs. 1.1 +/- 1.6 mmol/l, P < 0.001), as was the within-day variability (M value 27.7 +/- 19.7 vs. 30.2 +/- 23.1, P = 0.007). The incidence of severe hypoglycemic events (58 vs. 36, P = 0.037) including coma (16 vs. 3, P = 0.004) was significantly lower with insulin lispro than with regular insulin. Patients felt that insulin lispro increased flexibility and freedom of lifestyle. CONCLUSIONS: In well-controlled IDDM patients, insulin lispro is associated with a lower risk of severe hypoglycemia and coma.

Adult↗
PubMed1997

Atherosclerosis.

Explore the source record for details and available documents.

Arteries↗
PubMed1996

Evidence for a sound movement area in the human cerebral cortex.

Human listeners can localize sounds by the difference in both arrival time (phase) and loudness between the two ears. Movement of the sound source modulates these cues, and responses to moving sounds have been detected in animals in primary auditory cortex and in humans in other cortical areas. Here we show that detection of changes in the interaural phase or amplitude difference occurs through a mechanism distinct from that used to detect changes in one ear alone. Moreover, a patient with a right hemisphere stroke is unable to detect sound movement, regardless of whether it is defined by phase or by loudness cues. We propose that this deficit reflects damage to a distinct cortical area, outside the classical auditory areas, that is specialized for the detection of sound motion. The deficit is analagous to cerebral akinotopsia (motion blindness) in the visual system, and so the auditory system may, like the visual system, show localization of specialized functions to different cortical regions.

Aged↗
PubMed1996

Aligning maps of visual and auditory space. Sensory maps.

Visual and auditory space are represented topographically in the superior colliculus in the midbrain. Recent experiments show that N-methyl-D-aspartate (NMDA) receptors play an important role in aligning auditory and visual maps during development.

Animals↗
PubMed1996

Factors influencing plasma lipid profiles including lipoprotein (a) concentrations in renal transplant recipients.

Fasting plasma cholesterol, triglycerides, high-density lipoprotein (HDL) and apoprotein (apo) B were elevated in 214 nondiabetic renal transplant recipients when compared to a reference group. Apo (a) was slightly but not significantly lower in transplant recipients (median 118 mg/dl, range 16-1680 vs 130 mg/dl, 10-1176) and this difference could be predicted from Lp (a) isoform analysis. Cholesterol, triglyceride, apo B and apo (a) concentrations correlated negatively with creatinine clearance but none of these parameters showed a significant association with proteinuria. Patients treated with steroids had higher plasma HDL concentrations than those receiving cyclosporin monotherapy (P < 0.01). The use of diuretics was associated with raised triglycerides (P < 0.001) and cholesterol (P < 0.01) and with reduced HDL (P < 0.01) whilst patients receiving beta-blockers had significantly higher triglycerides (P < 0.01) and lower HDL levels (P < 0.02). In multiple regression analysis, age (P < 0.01), creatinine clearance (P < 0.05) and diuretic therapy (P < 0.005) were independent risk factors for increased cholesterol whilst apo (a) levels correlated negatively with creatinine clearance (P < 0.005). These results suggest that impaired renal function, steroids and non-immunosuppressive drugs contribute to lipid abnormalites in renal transplant recipients.

Adrenergic beta-Antagonists↗
PubMed1996

The topographical organization of descending projections from the central nucleus of the inferior colliculus in guinea pig.

We describe the descending projections from the central nucleus of the inferior colliculus (CNIC) in guinea pig. Focal injections of the tracer biocytin, made in physiologically defined frequency regions of the CNIC, labelled laminated axonal terminal fields in the ipsilateral dorsal nucleus of the lateral lemniscus, and bilaterally in the ventral nucleus of the trapezoid body and the dorsal cochlear nucleus. Labelling was also present in the rostral periolivary nucleus, but we could not distinguish a clear border between the terminal fields in this nucleus and those in the ventral nucleus of the trapezoid body. Labelling observed in the ventral nucleus of the lateral lemniscus, and to a lesser extent in the dorsal nucleus of the lateral lemniscus, was accompanied by retrogradely labelled somata and therefore we cannot conclude unequivocally that the CNIC projects to these lemniscal nuclei. Where the labelling was ordered topographically, its position varied as a function of the best frequency at the injection site. High-frequency regions in the CNIC project to the medial parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus, while low-frequency regions in the CNIC project to the lateral parts of the ventral nucleus of the trapezoid body and dorsal cochlear nucleus. Additional axonal labelling with terminal boutons, but with no apparent topographical arrangement, was present in the ipsilateral horizontal cell group, sagulum, and also bilaterally in the superficial granule cell layer of the ventral cochlear nucleus and layer 2 of the dorsal cochlear nucleus. Our findings are consistent with the existence of tonotopically organised feedback projections from the CNIC to the brainstem nuclei that project to it.

Animals↗
PubMed1996

Outcomes of time-limited psychotherapy in applied settings: replicating the Second Sheffield Psychotherapy Project.

In a replication and extension of the Second Sheffield Psychotherapy Project (SPP2), a collaborative psychotherapy project (CPP) was carried out at 3 sites within the National Health Service of the United Kingdom. Clients (N = 36) stratified at 3 levels of severity of depression were randomly assigned to one of 2 treatment approaches (psychodynamic-interpersonal or cognitive-behavioral) of 2 time-limited durations (8 or 16 sessions). Gains in both treatment approaches were approximately equivalent and were similar for CPP and SPP2 clients when measured at the end of treatment. However, CPP patients did not maintain their gains to the extent that the SPP2 clients did at 3-month and 1-year follow-up assessments. In the CPP, clients given 16 sessions showed a statistically significant advantage over clients given 8 sessions on some measures at some assessments; in the SPP2, similar effects were noted only among some subgroups of clients.

Adult↗
PubMed1996

Dose-effect relations in time-limited psychotherapy for depression.

Criteria for reliable and clinically significant improvement were applied to standard and individually tailored outcome measures data from 212 depressed clients who had been randomly assigned to receive either 8 or 16 sessions of time-limiting psychotherapy. The data were used to address 2 questions: (a) Is the dose-effect curve for psychological symptoms negatively accelerated? and (b) is there a differential rate of response for acute, chronic, and characterological/interpersonal components of depression? The results supported the differential rate of response of different components of depression and suggested qualifications to the acute, chronic, and characterological/interpersonal components and evidence that both supported and qualified previous suggestions that the dose-effect curve is negatively accelerated.

Adult↗
PubMed1996

Contribution of GABA- and glycine-mediated inhibition to the monaural temporal response properties of neurons in the inferior colliculus.

1. To determine the contribution of inhibition to the generation of the temporal response patterns of neurons in the inferior colliculus (IC), the effects of iontophoretically applied gamma-aminobutyric acid (GABA), glycine, and the GABAA and glycine receptor antagonists, bicuculline and strychnine were studied on 121 neurons in the IC of urethan-anesthetised guinea pig. 2. The neurons temporal discharge patterns were classified into six categories on the basis of their peristimulus time histograms (PSTHs). 1) Onset units fired at the stimulus onset and could be divided into two subtypes: narrow (1-2 spikes only) or broad (response lasting up to approximately 30 ms). 2) Pauser units had a precisely timed onset peak separated from a lower level of sustained activity by either a marked reduction or complete cessation of firing. 3) Chopper units had three or more clearly defined peaks near stimulus onset or evidence of regularly spaced peaks over the duration of the stimulus. 4) Onset-chopper units had three clearly defined peaks at onset but no sustained firing. 5) On-sustained units had a clearly defined single onset peak followed by a lower level of sustained activity. 6) Sustained units fired throughout the stimulus, but lacked an onset peak. 3. Iontophoretic application of GABA and glycine produced a dose-dependent reduction in firing rate in 76% (42/55) and 79% (11/14) of units, respectively. Application of bicuculline or strychnine increased the discharge rate in 91% (64/70) and 94% (16/17) of neurons, respectively. 4. The effects of bicuculline and strychnine on PSTH class were studied in detail on 70 neurons. Changes in discharge rate were accompanied by changes in PSTH in 49% (34/70) of neurons tested with bicuculline and 41% (7/17) tested with strychnine. Pauser units were the most affected with 69% changing their PSTH class, but some units in all PSTH classes, except the chopper group, exhibited changes in PSTH pattern after application of bicuculline. The majority of units (approximately 50%) that changed PSTH pattern in the presence of bicuculline became chopper units. Units of all PSTH classes could become choppers, but the proportion of units showing this change was dependent on the unit's control response pattern. All seven units that changed PSTH class with strychnine also became choppers. Changes in PSTH, including the appearance of a chopper pattern, did not depend on either a unit's control discharge rate or the magnitude of the change in discharge rate induced by the antagonists. 5. Bicuculline and strychnine had no significant effect on latency for units in the chopper, onset-chopper, onset, pauser, and on-sustained groups. A few sustained and unclassified units that had long predrug latencies did show marked reductions in latency when tested with bicuculline. 6. The majority of units did not fire spontaneously, and neither bicuculline or strychnine produced a significant increase in spontaneous rate. 7. In many units, the changes in firing rate did not occur equally over the duration of the response. Firing rates at the onset and in the last quarter of the sustained response were compared. Three effects of bicuculline and strychnine were observed. For 80% of units the largest change in firing rate occurred in the sustained response, while in 14% of units the change was greatest at onset.

Acoustic Stimulation↗
PubMed1996

Diagnosis of Hirschsprung's disease.

OBJECTIVE: Our aims were to determine the validity of using low-osmolality water-soluble contrast enemas (WSCE) in neonates and infants with suspected Hirschsprung's disease (HD) and to devise a scoring system that uses a checklist of radiologic signs to determine the probability of HD. MATERIALS AND METHODS: The records of all patients referred by pediatric surgeons from 1988 through 1992 for the radiologic investigation of possible HD were retrospectively reviewed. Thirty-eight patients who were from 2 days to 9 months old were studied; 20 of them were neonates (less than 1 month old). Of all the patients, 24 underwent WSCE and the other 14 underwent barium enema. For all patients, HD had been diagnosed by rectal biopsy or excluded by biopsy, clinical follow-up, or both. Radiographs were read by a gastrointestinal radiologist who used a checklist of diagnostic criteria reported in the literature. The sensitivity had specificity of the findings were compared with those in the literature. RESULTS: Of the 18 patients with HD, 12 were neonates. All reported radiologic diagnostic criteria were seen; the frequency, sensitivity, and specificity of the findings were reported. Twenty percent (n = 2) of HD patients in the WSCE group (n = 10) had negative findings. Two of the 12 neonates developed colonic perforation, one during the enema and the other within 24 hr of the procedure. CONCLUSION: WSCE has a sensitivity and specificity equivalent to those of the barium enema for the detection of HD. For the two patients with perforation, the use of WSCE was of considerable benefit, avoiding the problems associated with barium spillage into the peritoneal cavity. A scoring system for diagnostic enemas is feasible.

Barium Sulfate↗