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Biomedical subjects

I Gordon

Publications and source records attributed to I Gordon.

At least 109 records · Page 6Linked to original sources
PubMed1995

[3H]GBR 12935 labels mainly the piperazine acceptor site in the rat prefrontal cortex.

The binding characteristics of [3H]GBR 12935, a ligand for the dopamine (DA) transporter, have been extensively investigated in the striatum. The present study was designed to characterize [3H]GBR 12935-binding to prefrontal cortex (PFC) in rats. This region receives a dense DA input from the ventral tegmental area and is suspected to play a major role in higher associative functions. We demonstrated high-affinity, saturable, mazindol-sensitive [3H]GBR 12935-binding in the rat PFC; however, in contrast to the striatum, such binding was inhibited by increasing concentrations of Na+. This fact, together with the irregular pattern of the association kinetics and the marked sensitivity of [3H]GBR 12935-binding to piperazine derivatives, indicates the possible presence of more than one [3H]GBR 12935-binding site in the PFC. Furthermore, it appears that [3H] 12935 in the rat PFC labels mainly 'the piperazine acceptor site' and not the DA transporter.

Animals↗
PubMed1995

Long-term effects of amygdaloid kindling on striatal dopaminergic terminals.

The present study assessed the effects of kindling on striatal DA terminals. Kindled and control rats were tested for DA transporter density using [3H]GBR-12935 binding to striatal membranes and for amphetamine and KCl-induced [3H]DA release from striatal slices. Kindling decreased the maximal number of [3H]GBR-12935 binding sites in the dorsal striatum of rats sacrificed either 2 h or 4 weeks after the last seizure but had no effect on stimulated fractional [3H]DA release. These findings suggest a minor damage to DA terminals in the dorsal striatum. At the same postseizure time points, kindling augmented the hyperlocomotion associated with novel environment. Explanation of this effect requires in vivo measures of striatal DA functioning.

Amygdala↗
PubMed1995

Cervical cytology reported as negative and risk of adenocarcinoma of the cervix: no strong evidence of benefit.

The relationship between negative cervical cytology reports and risk of adenocarcinoma of the cervix was evaluated in a case-control study of 113 cases and 452 controls. All cases and controls had received at least two negative cytology reports. There was no significant difference between the cases and controls in the number of negative cytology reports or in history of cervical abnormality; while a test for trend in the time since last negative cytology report was significant (P < 0.001), the estimated benefit was very modest. Although the estimates of relative protection were higher in women aged less than 35 years than in women aged 35-69 years, this difference was not statistically significant. These results suggest that cervical screening as practised in the 1970s and 1980s was much less effective in preventing adenocarcinoma than squamous carcinoma of the cervix.

Adenocarcinoma↗
PubMed1995

Absolute 99Tcm-DMSA renal uptake in children: optimum time to scan.

Absolute renal uptake was measured at 2, 4 and 6 h in 27 patients in order to determine a more convenient time for uptake compared with the 6-h measurement proposed by other authors. Measurements made at 2 and 4 h would need to be increased by 20 and 6%, respectively, to convert to the value at 6 h. Measurements at 4 h are a reasonable compromise to achieve a high-count/low-background image in a reasonable time and to obtain a good estimate of the predicted 6 h uptake at a single scanning session. The percent renal uptake at 6 h, U(6), can be derived from the percent uptake measured at t hours after injection, U(t), using the following formula: U(6) = U(t) x CF(t), where CF(t) = 1.0 + 0.03 (6 - t) for 4 < or = t < or = 6.

Adolescent↗
PubMed1995

Children with intractable focal epilepsy: ictal and interictal 99TcM HMPAO single photon emission computed tomography.

Fourteen children with intractable complex partial seizures underwent ictal and interictal 99TcM HMPAO single photon emission computed tomography (SPECT) scans. Abnormalities concordant with clinical and/or EEG localisation were present in 13 of 14 ictal and/or interictal scans. Focal hyperperfusion was seen at the seizure focus on ictal scans and focal hypoperfusion was seen on interictal scans. The timing of the injection in relation to the start of the seizure was crucial for reliable localisation. While recognisable patterns of regional cerebral blood flow (rCBF) were seen on either interictal or ictal scans, marked changes in the patterns of rCBF between the ictal study and interictal study provided the most reliable information about seizure localisation. Using both ictal and interictal studies, 99TcM HMPAO SPECT may provide data about both the seizure origin and its relationship to structurally abnormal regions of the brain.

Adolescent↗
PubMed1995

Migration in a segmented labour market.

"Current research in migration is moving on from neo-classical and behavioural perspectives to a more structural approach relating to wider processes, issues of power and the particular role of employers. Within this programme a key issue for investigation is the interaction between spatial mobility and the structuring of labour markets. This paper focuses on the significance of labour market segmentation--in terms both of job stability and gender--for migration, both theoretically and through an empirical analysis of data from the UK Labour Force Survey on sponsored and unsponsored moves."

Demography↗
PubMed1994

The effect of repeated amphetamine treatment on striatal DA transporter and rotation in rats.

The effect of repeated amphetamine treatment on the involvement of the striatal DA transporters in rotation behavior was tested in rats. Repeated amphetamine treatment had no effect on [3H]DA uptake or [3H]GBR-12935 binding density. However, unlike the naive rats who rotated away from the striatum with a lower density of DA transporters, rats sensitized to amphetamine rotated toward the striatum with a lower density of DA transporters. These findings imply that repeated amphetamine augments the subcortical involvement in behavioral output.

Animals↗
PubMed1994

Cost to industry of illnesses related to alcohol and smoking. A study of Telecom Australia employees.

OBJECTIVE: To estimate the direct cost to industry of absenteeism attributable to drinking alcohol and smoking. DESIGN: Review of sick leave and superannuation data in the staff records of Telecom Australia (nearly 80,000 staff) for the financial year 1991-92 to identify illnesses related to alcohol or smoking. Costs were calculated by reference to tables of aetiological fractions, which statistically attribute a proportion of an illness to alcohol or smoking. MAIN OUTCOME MEASURE: The cost of employee absences attributable to alcohol or smoking expressed in the value of the person's daily salary. RESULTS: Illness attributable to smoking or alcohol accounted for 25% of sick leave. The estimated costs were $5,500,000 for alcohol and $16,500,000 for smoking. The total cost of $22,000,000 averages $275 per employee per year. If this cost is extrapolated to the rest of the Australian workforce, the total would exceed $2,000,000,000 a year. CONCLUSION: Limitations in the data mean that our results are likely to be underestimates. The direct costs to industry of ill health caused by alcohol and smoking are substantial and warrant preventive and rehabilitative programs.

Absenteeism↗
PubMed1994

Bilateral imbalance in striatal DA-uptake controls rotation behavior.

We tested the relation between bilateral imbalance in striatal DA uptake and asymmetric rotation behavior. Rats were screened for either spontaneous or amphetamine-induced preferred direction of rotation and the presynaptic DA transporter in the ipsi- and contralateral striatum was characterized in vitro by measuring [3H]DA uptake or [3H]GBR-12935 binding. DA uptake was lower in the striatum contralateral to either the spontaneous or amphetamine-induced preferred direction of rotation. Similar imbalance in the density of the transporter was confirmed by the binding experiments. These results support the hypothesis that striatal imbalance in DA uptake produces asymmetric behavior during spontaneous rotation. Further studies are required to assess the involvement of DA transporter imbalance in amphetamine-induced behavioral asymmetry.

Amphetamine↗
PubMed1994

Effect of follicle size on bovine oocyte quality and developmental competence following maturation, fertilization, and culture in vitro.

The aim of the present series of experiments was to investigate the effect of the size of follicle from which the oocytes originate on their subsequent in vitro developmental ability. Ovarian follicles were isolated and grouped according to size (2-6 mm, > 6 mm). Primary oocytes were carefully liberated and grouped according to morphology into one of five categories: denuded; expanded; with two or three layers of cumulus; with four or five layers; and with many (six or more) layers. Following in vitro maturation (IVM), fertilization (IVF), and culture (IVC), more oocytes with many layers of cumulus (P < 0.01, 70.2%, 73/104 vs. 46.8%, 87/186, respectively) and a higher proportion of blastocysts were obtained from follicles > 6 mm compared to 2-6 mm follicles (P < 0.01, 65.9%, 60/91 from > 6 mm follicles vs. 34.3%, 34/99 from 2-6 mm follicles, respectively). Use of follicular fluid (BFF) from follicles of different sizes in the IVM medium did not significantly increase the cleavage rate or blastocyst yield compared to controls. Administration of porcine follicle-stimulating hormone (pFSH) to donors prior to slaughter was investigated as a possible means of increasing the number of larger sized follicles in the ovaries and, thereby, the quality of the recovered oocytes. It was found that administration of six injections of pFSH beginning 3 days prior to slaughter resulted in a significant increase (P < 0.001) in the proportion of follicles > 6 mm in diameter (31.6%) compared to that in nontreated controls (6.6%) and to animals that received only four injection groups (9.4%).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1994

Effect of renal maturation on the clearance of technetium-99m mercaptoacetyltriglycine.

To investigate the effect of growth and maturation on the global kidney clearance of technetium-99m mercaptoacetyltriglycine (99mTc-MAG3), we investigated 509 children who attended for 99mTc-MAG3 renography in our department. In order to estimate the normal maturation of the kidney, only children who were classified as "normal" using diagnostic criteria were included in this study (n = 109). Kidney clearance was calculated using a gamma camera technique and a 20-min blood sample. There was a progressive increase in the clearance of 99mTc-MAG3 throughout childhood and into adolescence (mean clearance value below 2 month was 31.4 ml/min, mean clearance value above 12 years was 287 ml/min). When clearance was normalised to body surface area (BSA) a different pattern was seen, with a progressive increase from 3 weeks of age (mean value < 0.2 years: 208 ml/min/1.73 m2) to a plateau at the end of the first year of life (mean value > 2 years: 303 ml/min/1.73 m2). Maturation of the kidney as defined by the normalised clearance of 99mTc-MAG3 is therefore complete by the end of the 1st year of life, after which any change in non-corrected clearance values may be attributed to growth. To investigate the appropriate normalisation factor for 99mTc-MAG3 clearance in children, clearance values were compared to height, weight and BSA. The relationships were described using a linear model; the correlation coefficients demonstrated that BSA has the highest strength of relationship with 99mTc-MAG3 clearance. Body surface area may be used over 1 year of age to normalise the clearance values of 99mTc-MAG3.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1994

[3H]GBR 12935 binding to human platelet membranes is sensitive to piperazine derivatives but not to dopamine uptake inhibitors.

It remains controversial whether blood platelet can be used as a peripheral model for the central presynaptic dopaminergic neurons. We investigated the existence of dopamine transport complex in human blood platelet membranes using the selective dopamine uptake inhibitor [3H]GBR 12935 as a radioligand. In contrast to [3H]GBR 12935 binding to rat striatal dopamine carrier site, the high affinity [3H]GBR 12935 binding to platelet membranes was insensitive to mazindol and other dopamine uptake inhibitors. Piperazine derivatives including GBR 12909 were found to be potent inhibitors of [3H]GBR 12935 binding to platelet membranes. [3H]GBR 12935, piperazine derivative-sensitive binding to platelet membranes was inhibited by increasing sodium concentration. Kinetic experiments revealed that both association and dissociation rates of [3H]GBR 12935 binding were slower to platelet membranes than to striatal membranes. These results indicate that [3H]GBR 12935 binding to platelet membranes is different from the binding of this ligand to the dopamine uptake complex and seems to label a "piperazine acceptor" site which was previously demonstrated in brain and liver membranes.

Animals↗
PubMed1994

Successful in vivo immunolocalization of Langerhans cell histiocytosis with use of a monoclonal antibody, NA1/34.

The antibody NA1/34 is a murine monoclonal antibody directed against the CD1a surface antigen expressed on normal Langerhans cells, cortical thymocytes, and on lesional cells in Langerhans cell histiocytosis (LCH). Our hypothesis was that NA1/34 would localize sites of disease activity in patients with multisystem LCH. To test this hypothesis, indium 111-labeled NA1/34 was administered to five patients with multisystem LCH and serial gamma scans were obtained for up to 120 hours. Serial serum samples were obtained from one patient for analysis of anti-mouse Ig antibody and NA1/34 levels. Direct and indirect immunofluorescence staining for CD1a and NA1/34 were performed on a tissue biopsy specimen from one patient after administration of the antibody. The 1- and 4-hour scans showed distribution of antibody in the blood pool, but in later scans localization of the antibody was noted in areas of known disease activity in all five patients. Bony lesions, previously seen on skeletal radiographs, were especially well identified. Serum kinetics studies showed clearance of the antibody from the blood pool within 12 hours of administration. Direct binding of NA1/34 to lesional cells was demonstrated by direct immunofluorescence. The only adverse effect was urticaria in one patient. We conclude that NA1/34 localizes disease activity in vivo in bones of patients with LCH with minimal toxic effects. An evaluation of its role in determining disease extent ("staging") and in treatment is now needed.

Adult↗
PubMed1994

Renal pathology and the 99mTc-DMSA image before and after treatment of the evolving pyelonephritic scar: an experimental study.

This study reports the effects of 3-weeks' antimicrobial treatment on the pathology and appearance of the 99mTc-DMSA renal image in piglets with pyelonephritis induced by a combination of vesicoureteral reflux (VUR) and urinary infection. Before treatment, either photon-deficient (B1, B2) or photon-absent (C) scintigraphic abnormalities were present in the refluxing kidney in all 22 animals examined. All (100%) of the initially B1 and the majority (71%) of B2 photon deficient defects resolved with treatment, leaving only insignificant residual pathologic lesions. Conversely almost all (93%) of the C photon-absent scintigraphic abnormalities persisted after treatment and were always associated with significant scarred or cratered pathologic lesions in the refluxing kidney at sacrifice.

Animals↗
PubMed1994

Renal pathology and the 99mTc-DMSA image during the evolution of the early pyelonephritic scar: an experimental study.

This study describes the pathologic changes underlying the appearances of the 99mTc-DMSA renal image during acute pyelonephritis induced in piglets by a combination of vesicoureteral reflux (VUR) and urinary infection. In a total of 42 animals examined, pathologic lesions were identified in 36 of the 46 kidneys subjected to VUR and urinary infection, but no lesions developed in the remaining 10 refluxing kidneys. While scintigraphic defects were invariably associated with pyelonephritic lesions (specificity 100%), some small lesions were not identified (sensitivity 80%). There was a significant association (p = < 0.001) between the degree of photon deficiency seen scintigraphically and the histologic changes (early and late lesions). However, the scintigraphic appearance of individual lesions was also influenced by factors such as their extent and density, so that consideration of the macroscopic characteristics was also important for precise correlation.

Acute Disease↗