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Biomedical subjects

S M Smith

Publications and source records attributed to S M Smith.

At least 253 records · Page 14Linked to original sources
PubMed1991

Temporal and regional differences in the expression pattern of distinct retinoic acid receptor-beta transcripts in the chick embryo.

Retinoic acid (RA) is a signaling molecule apparently involved in a variety of morphogenetic processes, such as patterning of developing and regenerating vertebrate limbs. RA binds to specific intracellular receptors that constitute a multigene family. RA receptors (RAR) bind to the regulatory region of specific target genes and thereby control the expression of these genes. Here we report the sequence and spatiotemporal expression pattern of RAR-beta from chick. Northern blots of RNA from whole embryos and from limb buds reveal the presence of transcripts of 3.2, 3.4, and 4.6 kb in size. Using two riboprobes, one that hybridizes to all three RAR-beta mRNAs and a second one, specific for the 4.6 kb transcript, we found by in situ hybridization a differential distribution of RAR-beta transcripts in limb bud mesenchyme, in craniofacial mesenchyme and in hindbrain neuroectoderm. In the hindbrain the 4.6 kb mRNA exhibits an anterior boundary of expression at the level of the constriction between rhombomeres 5 and 6. Examination of neural plate stage embryos by in situ hybridization indicates that this boundary of expression is already defined by this stage. In addition to having several RA receptors that are expressed with distinct spatial patterns in the embryo, our data indicate that the expression pattern of transcripts derived from a single receptor gene can also be differentially expressed, thus providing another level for regulating RA action.

Amino Acid Sequence↗
PubMed1991

The differential effect of cigarette smoke on the growth of bacteria found in humans.

The effect of cigarette smoke on growth of those species of bacteria that are considered common potential human pathogens was examined in vitro. Smoke from both mentholated and nonmentholated cigarettes inhibited the growth of Gram-positive cocci to a greater degree than that of Gram-negative rods. Staphylococcus aureus, Streptococcus pneumoniae, and a variety of other streptococci were inhibited at a smoke solution dilution of 1:8. Enteric bacteria such as Klebsiella, Enterobacter, and Pseudomonas were not affected by a 1:1 dilution of the solution. As with the Gram-positive cocci, the Neisseria species and Branhamella were also inhibited at a dilution of 1:8. Culture results of the mouth of 15 smokers and 15 nonsmokers showed that the smokers have a propensity to develop heavy Gram-negative bacterial colonization.

Bacteria↗
PubMed1991

Incubated reminiscence effects.

Reminiscence, the recall of material that was not successfully recalled on a previous attempt, was examined in three experiments as a function of the interest (incubation) interval. Incubation intervals inserted between successive recall tests resulted in increased reminiscence, but the effect was seen primarily in the first retested minute. Neither the duration of the initial test (1-4 min), nor the incubation activity (maze problems vs. rest) affected this incubated reminiscence effect. The results support models in which recall tests cause output interference, but incubation intervals reduce it.

Cognition↗
PubMed1991

Familial cardiac amyloidosis. Diagnosis by immunocytochemistry.

Familial cardiac amyloidosis is a rare disorder that is difficult to diagnose. There is no specific therapy for this disease, but it is important to distinguish the cardiac and gastrointestinal symptoms of this disease from those of other treatable causes. We have treated a patient with this disorder who presented with cardiac and gastrointestinal symptoms. The diagnosis of amyloidosis was suspected on rectal biopsy and was confirmed by immunocytochemistry and immunoalkaline phosphatase technique. Pre-albumin was demonstrated in the lesion. We concluded that when familial amyloidosis is suspected, a biopsy from the suspected organ system is helpful for the diagnosis. The detection of pre-albumin by immunocytochemistry can elucidate the diagnosis of familial amyloidosis.

Aged↗
PubMed1991

Incubation and the persistence of fixation in problem solving.

Extra work on unsolved problems may lead to more improvement if the new work is delayed rather than undertaken immediately after initial solution attempts. Such a result constitutes incubation in problem solving. "Unconscious work" on a problem, commonly assumed to be responsible for incubation effects, may not be necessary to observe the phenomenon. We hypothesize that fixation, a block to successful problem solving, may develop during initial solution attempts and persist, interfering with immediate extra work more than with delayed extra work. Five experiments are reported in which fixation was induced to prevent optimal performance on the initial test of Remote Associates Test (RAT) problems (e.g., Mednick, 1962). After the fixation manipulation in three of the experiments, the effects of incubation intervals were examined by retesting the fixated problems. Both fixation (poorer initial problem-solving performance) and incubation (more improvement after a delayed retest than an immediate retest) were found in all the experiments which tested for the effects. In Experiments 1, 2, and 3, misleading distractors were presented alongside the RAT problems during the initial test of the problems to cause fixation. In Experiment 4, a block of paired associates--pairing the RAT words with the misleading distractors prior to problem solving--successfully induced fixation, indicating that the distractors affected memory retrieval. In Experiment 5, a trial-by-trial technique allowed fixation and incubation to be induced and tested separately for each item. All of our findings of incubation effects appear to have depended upon the initial induction of fixation. Although the experiments may not be representative of all naturally occurring cases of incubation, they provide a methodology for the study of fixation and incubation effects in problem solving in the laboratory.

Adult↗
PubMed1990

Developmental regulation of expression of the malate synthase gene in transgenic plants.

The cucumber malate synthase (MS) gene, including 1856 bp of 5' non-transcribed sequence, has been transferred into Petunia (Mitchell) and Nicotiana plumbaginifolia plants using an Agrobacterium binary vector. The transferred gene is found in variable copy number in different transformants, and is stably transmitted in each case as a single Mendelian character. Transgene mRNA accumulates in the seedling during the first three days of germination, then declines in amount as the cotyledons emerge from the seed. The decline is more pronounced in light-grown seedlings than in dark-grown seedlings. Expression of the MS transgene is also detected at a low level in petals of transformed Petunia plants. In these respects the pattern of MS gene expression is similar in cucumber and in transformed plants, showing that the transferred DNA fragment contains a functional MS gene. A 1076 bp fragment of 5' sequence was linked to the beta-glucuronidase reporter gene and transferred into Nicotiana, where it was shown to direct temporal and spatial patterns of expression similar to that of the complete MS gene. However, histochemical localisation of beta-glucuronidase activity demonstrated that the chimaeric gene is expressed not only in cotyledons of transgenic plants, but also in endosperm and some hypocotyl cells during early germination. The relevance of these findings to the control of malate synthase gene expression is discussed.

Base Sequence↗
PubMed1990

Epidemiology of ciprofloxacin resistance among patients with methicillin-resistant Staphylococcus aureus.

During the first twelve months after ciprofloxacin was introduced for clinical use at our institution, 65 new patients were found to be either infected or colonized by methicillin-resistant Staphylococcus aureus (MRSA) which were also ciprofloxacin resistant (CR-MRSA). Only 18 of these patients (28%) had been previously exposed to this antibiotic. Nine (50%) of the 18 patients had received ciprofloxacin for treatment for a pathogen other than MRSA. Although the initial cases of colonization or infection with CR-MRSA can be directly related to ciprofloxacin use, many of the subsequent cases of colonization and infection were not the consequence of ciprofloxacin therapy but rather hospital transmission of existing CR-MRSA.

Ciprofloxacin↗
PubMed1990

A comparison of three formulations of TAC (tetracaine, adrenalin, cocaine) for anesthesia of minor lacerations in children.

A randomized, prospective, double-blind study comparing three formulations of the topical anesthetic solution TAC for laceration repair was undertaken in 250 children. The children's wounds were anesthetized with either TAC I (original formulation--0.5% tetracaine, 1:2000 Adrenalin, 11.8% cocaine), TAC II (1.0% tetracaine, 1:4000 Adrenalin, 7.0% cocaine), or TAC III (1.0% tetracaine, 1:4000 Adrenalin, 4.0% cocaine) prior to repair. The solutions were compared with respect to efficacy, acceptability, wound complications, and side effects. We found comparable efficacy of the three formulations, with similar efficacy to 1% lidocaine infiltration for facial and scalp wounds. Anesthesia for extremity wounds was adequate in only 39.9% of cases, regardless of TAC strength. Wound complications and side effects were within expected and acceptable limits. Our findings support use of TAC for face and scalp lacerations and a change to a less concentrated TAC preparation, such as our "TAC III," which is presumably safer for widespread use.

Adolescent↗
PubMed1990

Imipenem resistance in a case of AIDS with relapsing Pseudomonas meningitis.

We describe an AIDS patient who had a recurrence of Pseudomonas meningitis to illustrate three points. First, the use of sulfamethoxazole-trimethoprim in AIDS patients for prophylaxis of Pneumocystis carinii pneumonia may cause the various body sites to be colonized with resistant species such as P aeruginosa. Second, Pseudomonas meningitis can recur in a patient with AIDS after a month of appropriate therapy. Finally, imipenem is a poor choice for Pseudomonas meningitis, even when alternative therapies appear much less attractive. High doses of imipenem should not be used for fear of seizures, and lower doses only produce resistant organisms in the CSF.

Acquired Immunodeficiency Syndrome↗
PubMed1990

Behaviour, physiological states and thermal characteristics of aggregating male Hybomitra illota (Diptera: Tabanidae).

Male Hybomitra illota (Osten Sacken) were found aggregating in clearings in wooded areas in Rondeau Provincial Park, Ontario, Canada. At these sites they perched on a variety of substrates, and made frequent flights in pursuit of insects flying overhead. We know that these pursuit flights were part of the mating behaviour because some pursuits of female H. illota resulted in copulation. We call the aggregation sites 'mating arenas' and the behaviour exhibited by males 'perch-and-pursue'. Aggregation occurred only on sunny days, when ambient temperatures exceeded 18 degrees C. Males perched in sunny areas, except during hot afternoons, when some males were found in dappled shade. Some marked males remained at or returned to sites for up to 13 days, but most males did not remain at the same area within a site, even during the same day. The contents of the oesophageal diverticula of males were depleted daily. Concentration of diverticular carbohydrates changed through the season. Thoracic temperatures of males were high (c. 37 degrees C) and were regulated, probably both behaviourally and physiologically. The sites and behaviour of male H.illota at aggregation arenas bear some resemblance to lek sites and lekking in vertebrates. Males are aggregated in an arena but, within the perching component of the behaviour, we saw no evidence of male territoriality, display, or female choice. However, competition, display, or mate choice could occur within the pursuit-flight component.

Animals↗
PubMed1990

Ad libitum alcohol ingestion does not induce renal IgA deposition in mice.

This study investigated the induction of alcohol abuse related IgA glomerulonephritis in mice, a disease we have previously described in humans and in rats with noncirrhotic alcoholic liver disease. A commercial liquid diet was fed ad libitum to 115 mice from three strains: C57BL/6J, BALB/cJ, and C3H/HeJ. Animals were divided into two groups: 60 received 30% of their caloric intake as ethanol--alcoholized; and 55 were fed the same calorie count in the form of glucose-controls. Mice were killed at weekly intervals after 4 to 10 weeks of liquid diet ingestion. No diagnostic renal pathology was observed.

Alcohol Drinking↗
PubMed1990

Dermal vascular IgA deposits in IgA nephropathy secondary to alcohol abuse.

Skin, kidney and liver samples were investigated from 103 people with evidence of alcohol abuse at forensic autopsy. The diagnosis of alcohol abuse was based on clinical history, post mortem blood alcohol level and liver pathology. The findings confirmed the frequent widespread vascular IgA deposition in individuals with evidence of alcohol abuse. The frequency of IgA deposition in superficial small vessels of the dermis was not significantly different between individuals with IgA nephritis (16/85) and without such pathology (7/38). Based on these results, it can be inferred that had a pre-mortem skin biopsy been performed, it would not have had clinical usefulness in predicting the renal disease.

Alcoholism↗