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Biomedical subjects

R Goldstein

Publications and source records attributed to R Goldstein.

At least 235 records · Page 13Linked to original sources
PubMed1984

The role of memory and integration in early time concepts.

The nature of 5- to 8-year-old childrens ' time concepts was examined by analyzing two possible explanations for the greater difficulty children demonstrate in comparing durations that differ in beginning times as compared to those that differ in ending times. The explanations were (a) poor recall of beginnings as compared to endings due to their lower salience, (b) difficulty in integrating information from both points and reliance on endings only due to their greater salience. The subjects were 630 boys and girls from kindergarten to second grade. The children were presented with a series of two lights in different orders and combinations and were asked to compare order of beginnings and endings, and duration of the two lights. Results contradicted the memory explanation. In addition, repetitious questioning about order of one point (beginning or ending) appeared to have shifted children's attention from that point to the complementary point. Possible sources of children's failure to integrate beginning and end points when comparing durations were discussed.

Attention↗
PubMed1984

Distribution of serotonin-immunoreactivity in juvenile Aplysia.

Serotonin-immunocytochemistry has been applied to whole mounts of the central nervous system and of several peripheral tissues from stage 12 juvenile Aplysia californica. The small size of animals at this stage permits visualization of the three-dimensional distribution of structures containing serotonin-immunoreactivity in unsectioned tissues. Many neuronal cell bodies are stained in addition to the giant cerebral neuron of the cerebral ganglion and cells in the RB cluster of the abdominal ganglia which previously had been characterized biochemically and pharmacologically as being serotoninergic. Neuronal cell bodies, both in central ganglia and in the wall of the gut, are encircled by plexuses of serotoninergic varicosities. The neuropil of ganglia and the eye also contain fine, immunoreactive axons bearing varicosities. Intraganglionic connectives and nerves contain many stout fluorescent axons. Serotoninergic varicosities are also observed in the connective tissue sheath surrounding central ganglia and nerves, as well as in heart and body muscle, blood vessels and gut.

Aging↗
PubMed1984

Sleep in the cat: raphe dorsalis and vasotocin.

To determine the relationship between the raphe nuclei and the sleep-inducing pineal peptide arginine vasotocin (AVT), we investigated the hypnogenic effects of intraventricularly administered AVT in adult cats with electrolytic lesions performed either in the raphe dorsalis nucleus (RDN) or the raphe pontis nucleus (RPN). The following results were observed: (a) RDN lesions produced a quantitative decrease in NREM sleep and a transitory increase in REM sleep and narcoleptic-like alterations of REM sleep in the first 2-5 postoperative days. On the eighth postoperative day, normal (prelesion) sleep parameters were restored. (b) RDN lesions prevented AVT from inducing its hypnogenic effects during the first 5 postoperative days, but the AVT hypnogenic effects reappeared when sleep parameters reached prelesion levels. (c) Although the RPN lesions produced a slight but statistically significant REM sleep decrease, this did not prevent AVT from inducing its hypnogenic effects. We conclude that (a) the anatomic site of AVT action within the brain may be related to RDN; (b) at least some of the sleep disturbances observed after RDN lesions (narcolepsy) may be due to damage of the AVT site of action or to modifications of AVT synthesis or release; (c) RDN belongs to a large neural circuit that includes the pineal gland and habenula, a circuit that may play an important role in the sleep-wake cycle by "fine-tuning" sleep mechanisms. We hypothesize that AVT could be the specific inhibitory neuromodulator of this neural circuit.

Animals↗
PubMed1984

Metastatic calcification of the stomach imaged on a bone scan.

A whole body bone scan obtained on a 21-year-old woman with sickle cell disease and chronic renal failure showed localization of the radionuclide diffusely in the stomach. The localization of the radionuclide represented metastatic calcification of the stomach caused by secondary hyperparathyroidism.

Adult↗
PubMed1984

Gastric handling of medium-chain triglycerides and subsequent metabolism in the suckling rat.

We have previously shown that preduodenal lipases account for 50% of the lipolytic capacity of 14-day-old rats. The present investigation was designed to study the kinetics of and optimal conditions for absorption of fat in the stomach of suckling rats and its subsequent distribution in the body. After the simultaneous instillation of medium-chain triglycerides (MCT) containing 1.25 microCi 2,3-[3H]trioctanoate and of long-chain triglycerides containing 1.25 microCi 1-[14C]glycerol trioleate into the stomach ligated at the pylorus, we were able to show that gastric absorption of fat is limited to MCT. Two and a half minutes after injection, 88.6% of the radioactivity in the wall of the stomach was associated with free fatty acids, proving that lipolysis had preceded the absorption of the majority of the MCT. The remainder of the radioactivity was found in mono-, di-, and triglycerides as well as with cholesterol ester and phospholipids. In the plasma, peak radioactivity was attained within 2.5 min and a steady state ensued which lasted at least 30 min. Over this time period, specific radioactivity continued to rise in the liver, suggesting that hepatic uptake proceeded at the same rate as gastric absorption. Uptake could also be demonstrated in the three other organs tested, the lungs, the heart, and the kidneys. Absorption of MCT at pH 3 was only 20% of absorption at pH 6, which is the physiological pH in the suckling rat stomach within the first 10 min after a feed. Both at pH 3 and at pH 6, the addition of sodium taurocholate increased absorption of MCT over threefold. It is likely that the absorption of MCT by the stomach is a physiological event in the suckling rat.

Absorption↗
PubMed1984

Phasmid P4: manipulation of plasmid copy number and induction from the integrated state.

"Phasmid" P4 is unusual in that it is capable of (i) temperate, (ii) lytic, helper-dependent, and (iii) plasmid modes of propagation. In this report we characterize most of the known P4 genetic functions as to their essential or nonessential roles in the stable maintenance of plasmid P4 vir1 (pP4 vir1 (pP4 vir1). We also identify growth conditions that can be used to stably maintain pP4 vir1 at any one of several different copy number levels (n = 1 to 3, n = 10 to 15, or n = 30 to 40). Analyses of a temperature-sensitive alpha derivative of pP4 vir1 show that shifting the temperature from 37 to 42 degrees C allows this mutant to maintain an integrated copy of the plasmid, whereas replication of free copies is repressed because of the nonpermissive condition for their DNA synthesis. Conversely, a shift from 42 to 37 degrees C can be used to reinstate plasmid propagation. The utility of the inducible states of pP4 vir1 is discussed with respect to its attributes as a vector with the potential for cloning inserts of DNA up to 33,000 base pairs in a wide range of bacterial hosts.

Coliphages↗
PubMed1984

Middle-component AERs during backward masking.

This study examined the middle-component averaged electroencephalic response (AER) to tonal stimuli presented in a backward-masking paradigm. Ss were 4 normal-hearing young adults. Tone-Only (TO), Masker-Only (MO), and Tone-Masker (TM) responses were collected. The visual impression was that the TO response was not significantly different from the extracted response to the tone (T) from the TM response. This result obtained when the tone in the TM condition was presented either slightly above (+5 db) or slightly below (-5 db) perceptual threshold. Backward masking was discussed in terms of two contrasting views of the auditory system: the classical auditory nervous system alone and a parallel system combining the classical auditory and the reticular sensory systems. Speculations were made for each system regarding the type of AER expected for a stimulus submerged in backward masking. The mechanism responsible for backward masking was seen as a preperceptual device that allows discrete samples of the auditory environment to be processed. This mechanism was discussed in terms of its possible relation to forward masking and to loudness enhancement.

Acoustic Stimulation↗
PubMed1983

Follow-up of solitary autonomous thyroid nodules treated with 131I.

We studied the long-term effects of 131I therapy for solitary autonomous thyroid nodules on the size of the nodule and on thyroid function. Twenty-three patients with autonomous thyroid adenomas that had been treated with 131I from 4 to 16.5 years earlier (mean, 8.5) were examined, and their thyroid function was tested. In 12 patients (54 per cent), the nodules were still palpable, and in 2 they had increased in size. Eight patients (36 per cent) had become hypothyroid. The incidence of hypothyroidism was not related to nodule size or the level of thyroid function before therapy with 131I or to the total dose of 131I that had been given. We conclude that 131I therapy for autonomous thyroid adenoma often causes hypothyroidism and in many cases does not eradicate the offending nodule.

Adenoma↗
PubMed1983

A GABAergic habenulo-raphe pathway mediation of the hypnogenic effects of vasotocin in cat.

Electrolytic lesions, performed in the lateral habenula of cats, specifically altered the sleep-wakefulness cycle and completely prevented the usual actions of intraventricularly administered vasotocin, which are to induce non-rapid eye movement sleep and to suppress rapid eye movement sleep. These alterations are (i) selectively related to lateral habenula, since similar lesions performed in thalamus 2 mm lateral to lateral habenula, were unable to prevent the actions of vasotocin or to reproduce the sleep alterations observed after habenular lesions, and (ii) reversible, since at eight days after habenular lesions there is a total return to normal of the sleep-wakefulness parameters, and vasotocin is able again to induce its hypnogenic effects. Opposite effects, characterized by an increase in non-rapid eye movement sleep and a decrease in rapid eye movement sleep, could be induced by a short (10 min) electrical stimulation of the lateral habenula, but not if the stimulating electrodes are placed 2 mm more laterally. Picrotoxin, a gamma-aminobutyrate antagonist, injected intraventricularly in normal cats was without any apparent effect on the sleep-wakefulness cycle if administered in a dose of 1 ng, but had sleep-increasing effects when administered in a dose of 100 ng. However, the smaller dose of picrotoxin (1 ng), when administered 15 min before vasotocin, completely blocked the hypnogenic effect of vasotocin. It is suggested that vasotocin acts within the brain by activating a descending gamma-aminobutyrate-containing habenulo-raphe pathway, and that this pathway plays an important role in the induction and/or organization of the sleep-wakefulness cycle.

Animals↗
PubMed1983

Psychoacoustic tuning curves and averaged electroencephalic responses in a patient with low-frequency sensory-neural hearing loss.

A 10-year-old girl whose bilateral, low-frequency, sensory-neural hearing loss had been noted three years earlier showed a drop in speech discrimination in her left ear with no corresponding decrease in pure-tone sensitivity. Psychoacoustic tuning curves and middle-component averaged electroencephalic responses to tone-pips suggested that damage to the left ear had become greater than indicated by the pure-tone audiogram, accounting for the drop in speech discrimination. This case suggests caution in inferring the magnitude of damage to the peripheral auditory system from tonal thresholds.

Audiometry, Evoked Response↗
PubMed1983

The fatty meal test: an alternative to stool fat analysis.

In view of the technical difficulties inherent in using stool fat estimations as a parameter of malabsorption, we used a fatty meal absorption test. Children under investigation for failure to thrive were divided into two groups, those having a normal stool fat output (less than 3.2 g/day) constituting the control group, and those having steatorrhea. After a fatty meal containing 25 g of margarine and 25 g of butter fat, we measured the rise of serum triglycerides and chylomicrons hourly for 5 h. Serum triglyceride rise of less than 100 mg/dl or less than 100% above basal values and the appearance of less than 7% of chylomicrons were considered pathological. Of our control group 95% had a normal rise of triglycerides; and 96% of our patients with steatorrhea had an abnormal rise. This test was more reliable than the two-point triglyceride test previously described for the diagnosis of fat malabsorption. The fatty meal test as described here is considered to be a useful test of absorptive function.

Celiac Disease↗
PubMed1982

Propagation of satellite phage P4 as a plasmid.

Satellite phage P4 has two known options for propagation. In its lytic cycle, its regulatory functions can act in trans to alter the actions of a helper virus (P2), which then provides necessary gene products, including capsid proteins. P4 also can be propagated in the absence of a helper as a prophage, with distinct sites for integration within the Escherichia coli chromosome. We determined that a single spontaneous mutation (vir1) of phage P4 allows a third mode of propagation: as a plasmid (along with continued integration into the host chromosome). Hence, the P4 regulatory element is capable of (i) temperate; (ii) lytic, helper-dependent; and (iii) plasmid modes of development. These findings emphasize the close relationship between defective viruses and plasmids.

Cloning, Molecular↗
PubMed1982

Impaired intestinal fat absorption in chronic renal failure.

We performed oral fat loading tests in 10 patients with chronic renal failure (CRF) on hemodialysis (5 children and 5 adults). Fat absorption was measured by hourly determination of serum triglycerides (TG), cholesterol (CHOL), and lipoproteins (LP) after oral administration of a 'milkshake' containing 50 g of fat of dairy origin. 10 age-matched healthy volunteers with normal fasting serum TG levels and 10 subjects with fasting hypertriglyceridemia served as controls. Mean fasting serum TG levels in CRF patients were elevated compared to normal controls (177.6 +/- 14.6 mg/dl, 2.0 +/- 17 mmol/l vs. 91.0 +/- 10.5 mg/dl, 1.03 +/- 12 mmol/l). 6 patients (4 adults, 2 children) had type IV LP patterns and 2 patients (both children) showed type IIb hyperlipidemia. In only 2 patients, 1 child and 1 adult were TG, CHOL and LP electrophoresis all normal. The oral fat loading test in all CRF patients showed delayed appearance of TG and chylomicrons (CHYL) in the bloodstream i.c. impaired or slow absorption of fat from the gut. In contrast to normal and hypertriglyceridemic controls, TG and CHYL levels in CRF did not decrease by 5 h after the oral fat load. This study demonstrates impaired intestinal fat absorption in children and adults with CRF.

Adolescent↗
PubMed1982

Gastric lipase in the newborn rat.

A substantial portion of rat milk triglycerides was hydrolyzed in the ligated stomach of suckling rats with excised lingual gland and pancreas, due to the action of gastric lipase. Free fatty acids were the main lipolytic products. There were some diglycerides and traces of monoglycerides. Medium chain length (C8-C12) fatty acids were predominantly recovered in the free fatty acid fraction, whereas the remaining tri- and diglycerides became richer in long chain (greater than or equal to C14) fatty acids suggesting a preferential lipolysis of medium chain fatty acid ester bonds. The lipase activity in extracts of stomach wall and sublingual gland tissue was more stable at acid pH and more resistant to the action of pepsin than the activity of pancreatic lipase. Trypsin strongly affected lingual lipase activity but only moderately reduced gastric and pancreatic lipase activity. Presence of sodium taurocholate made the lingual and gastric lipases less sensitive to proteolytic attack. It was also found that the activity of gastric lipase, related to the tissue protein content, decreased with the age of rats, whereas that of lingual lipase increased. The joint capacity of the stomach and lingual gland lipases amounted to about 50% of the total digestive lipolytic capacity 6 days after rat birth but decreased to about 20% at 60 days of life. This was due mainly to the considerable increase in the pancreatic gland size.

Age Factors↗