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S Maddison

Publications and source records attributed to S Maddison.

15 recordsLinked to original sources
PubMed1993

Rapid competitive enzyme-linked immunosorbent assay using a monoclonal antibody reacting with a 15-kilodalton tegumental antigen of Schistosoma mansoni for serodiagnosis of schistosomiasis.

A competitive enzyme-linked immunosorbent assay (CELISA) for antibody detection was developed by using a monoclonal antibody which reacts with a 15-kDa tegumental antigen of the adult worm of Schistosoma mansoni. This monoclonal antibody was not able to react with antigens of Schistosoma japonicum or Schistosoma haematobium in enzyme-linked immunoelectrotransfer blot (EITB) and indirect immunofluorescence tests. The assay was performed in a period of 1 h using an adult worm crude extract antigen. To evaluate the CELISA, a total of 73 serum samples was analyzed: 35 were from S. mansoni-infected patients, 23 were from individuals with parasitic infections other than schistosomiasis, and 14 were from healthy individuals. All serum samples from healthy individuals and from patients infected with other parasites were negative, as were two (6%) samples from patients infected with S. mansoni. EITB analysis showed that 32 of 33 CELISA-positive samples were positive in the EITB but with different patterns of reactivity. A 15-kDa protein reacted with 60% of serum samples, and a 60-kDa protein showed the highest level of reactivity (85%). The two samples from patients infected with S. mansoni that were negative in the CELISA reacted with 70-, 60-, 50-, 47-, and 38-kDa proteins. One sample, positive in CELISA, did not react with proteins of the antigenic extract.

Adolescent↗
PubMed1983

Diencephalic neuronal activity during acquisition and ingestion of food in sheep.

Single unit recordings were made in the lateral hypothalamic region and ventrobasal thalamus in conscious sheep during presentation of food and feeding. Unit responses to all aspects of testing were observed between the two areas. However, analysis of the data revealed a functional division of unit types between the two regions. Unit responses specific to the sight of food, to the approach of food to the mouth, and during ingestion of food were observed in the lateral hypothalamic area, but not the ventrobasal thalamus. These responses were not associated with specific or generalized movements, non-specific arousal, with olfactory stimulation, or with other oral stimuli. Units responding in association with specific mouth movements or somatosensory stimulation of the face or mouth-parts were observed in the ventrobasal thalamus but not in the lateral hypothalamic area. In the case of movement-related activity, the response was independent of the stimulus inducing the movement, food and non-food stimuli being equally effective. This was also true of the somatosensory responses observed. Two possibilities in relation to this functional division are discussed. Firstly, that the ventrobasal thalamus receives oral sensory afferents which may be associated with the thalamic area for taste. Secondly, that the activity of hypothalamic cells recorded in the sheep is consistent with a role for this area of the brain in the guidance and control of ingestive behaviour in ruminant as well as non-ruminant species.

Animals↗
PubMed1983

The orbitofrontal cortex: neuronal activity in the behaving monkey.

Single unit recording of neurons in the orbitofrontal cortex of the alert rhesus monkey was used to investigate responses to sensory stimulation. 32.4% of the neurons had visual responses that had typical latencies of 100-200 ms, and 9.4% responded to gustatory inputs. Most neurons were selective, in that they responded consistently to some stimuli such as foods or aversive objects, but not to others. In a number of cases the neurons responded selectively to particular foods or aversive stimuli. However, this high selectivity could not be explained by simple sensory features of the stimulus, since the responses of some neurons could be readily reversed if the meaning of the stimulus (i.e. whether it was food or aversive) was changed, even though its physical appearance remained identical. Further, some bimodal neurons received convergent visual and gustatory inputs, with matching selectivity for the same stimulus in both modalities, again suggesting that an explanation in terms of simple sensory features is inadequate. Neurons were also studied during the performance of tasks known to be disrupted by orbitofrontal lesions, including a go/no go visual discrimination task and its reversal. 8.6% of neurons had differential responses to the two discriminative stimuli in the task, one of which indicated that reward was available and the other saline. Reversing the meaning of the two stimuli showed that whereas some differential units were closely linked to the sensory features of the stimuli, and some to their behavioural significance, others were conditional, in that they would only respond if a particular stimulus was present, and if it was the one being currently rewarded. Other neurons had activity related to the outcome of the animal's response, with some indicating that reinforcement had been received and others, that an error had been made and that a reversal was required. Thus, neurons in the orbitofrontal cortex possess highly coded information about which stimuli are present, as well as information about the consequences of the animal's own responses. It is suggested that together they may constitute a neuronal mechanism for determining whether particular visual stimuli continue to be associated with reinforcement, as well as providing for the modification of the animal's behavioural responses to such stimuli when those responses are no longer appropriate.

Animals↗
PubMed1980

Drinking in the rhesus monkey: peripheral factors.

Rhesus monkeys prepared with chronic cannulae implanted in the stomach and duodenum were water deprived for 22.5 hr. With both cannulae closed, a mean of 137 ml was drunk within a 60-min period. When ingested water drained freely from an open gastric cannula, continuous drinking far in excess (878 ml mean intake) of normal occurred. Sham drinking also exceeded (634 ml mean intake) normal when ingested water drained through an open duodenal cannula. This pattern of continuous sham drinking indicates that oropharyngeal stimulation is not sufficient alone, or together with the passage of water through the stomach and the initial part of the duodenum, to terminate drinking. Duodenal infusions of water (25-100 ml) slowed or stopped gastric sham drinking in a dose-dependent fashion, but equivalent infusions of isotonic saline were without effect. Thus, pre- or postabsorptive signals at or beyond the level of the intestine distal to the site of the duodenal cannula are probably important for the termination of drinking in the rhesus monkey.

Animals↗
PubMed1980

Drinking in rhesus monkeys: role of presystemic and systemic factors in control of drinking.

The effect of 24-hr water deprivation and subsequent drinking on systemic fluid balance was determined in rhesus monkeys prepared with indwelling cardiac catheters. Significant intracellular and extracellular depletions, as indicated by increased plasma sodium concentrations, osmolality, and plasma protein concentrations, resulted from the deprivation. An early attenuation in rehydrational drinking rate (2--4 min) was not associated with changes in systemic fluid balance, which suggests presystemic influences on behavior at this time. When drinking terminated (10 min), however, plasma dilution was significant. In experiments in which monkeys were sham drinking (open gastric cannula), water but not isotonic saline infusions, given through an intestinal cannula, reduced drinking rate and produced significant plasma dilution. Intravenous water infusions reduced drinking to only a comparable extent despite more rapid and substantial plasma dilution. Thus, systemic absorption does not account entirely for the effect of intestinal water infusions on drinking. It is concluded that stimulation of mechanisms both presystemically (within the intestine or the hepatic portal circulation) and systemically is important in the control and termination of rehydrational drinking in this species.

Animals↗
PubMed1979

Effect of Diazepam at the neuromuscular junction. A clinical study.

In patients undergoing surgery under general anaesthesia diazepam 0.16 mg kg-1 had no effect on mechanical twitch height of the adductor pollicis muscle of the thumb when the ulnar nerve was stimulated at the wrist. The muscle responses were evoked by single, repeated supramaximal stimuli at 0.2 Hz and "train-of-four" stimulation at 2 Hz for 2 s. Diazepam 0.16 mg kg-1 had no effect on the depth or recovery of neuromuscular blockade produced by suxamethonium, tubocurarine, pancuronium, fazadinium or alcuronium.

Anesthesia, General↗
PubMedDate not supplied

Hypothalamic unit responses to alimentary perfusions in the anesthetised rat.

Single unit discharges in the ventromedial hypothalamic nucleus (VMH) and lateral hypothalamic area (LH) were extracellularly recorded in urethane anesthetised female rats, while various solutions were perfused through the stomach or duodenum via implanted polythene tubes. Perfusates, which were maintained at 38 degrees C, were 0.9% (w/v) NaCl, 2.5% NaCl, 5.25% glucose, 30% glucose, 5.0% casein hydrolysate, and liquid food. Only units which did not respond to somatosensory stimuli were tested. One hundred and twenty six units were recorded for periods of up to 3 hr, occasionally longer, in 57 animals. Of these, 74 were recorded during gastric perfusions and 52 during duodenal perfusions. Distension of the stomach elicited changes in firing rate in 16 LH and 8 VMH units. Both increases and decreases in firing rate in response to gastric distension were observed in both the LH and VMH. There was no evidence that nutrient or osmotic properties of the perfusates exerted any modifying influence on hypothalamic unit discharges. Distention of the duodenum by the perfusions elicited changes in firing rate in 12 LH and 6 VMH units. In this case all LH units decreased firing and all VMH units increased firing during distension of the lumen. In addition 2 VMH units appeared to increase their firing rate in association with glucose perfusions. The results are discussed in terms of the role of gastrointestinal feedback to the hypothalamus in food intake regulation.

Animals↗