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Biomedical subjects

S L Adams

Publications and source records attributed to S L Adams.

At least 73 records · Page 4Linked to original sources
PubMed1990

Relative bradycardia in patients with isolated penetrating abdominal trauma and isolated extremity trauma.

A relative bradycardia is sometimes seen in patients with hemorrhagic shock. The phenomenon of relative bradycardia in civilian patients with isolated penetrating abdominal trauma and isolated severe extremity trauma who presented to an urban trauma center was studied retrospectively. Relative bradycardia was defined as a pulse rate of less than 100 with a concomitant systolic blood pressure of less than 100 mm Hg. There were 256 patients with isolated penetrating abdominal trauma and 938 patients with isolated severe extremity trauma. The incidence of relative bradycardia was 3.1% (eight of 256) in the group with abdominal trauma and 1.8% (17 of 938) in the group with extremity trauma. A pulse rate less than 100 was documented in 35.2% of all patients presenting with a systolic blood pressure less than 100 mm Hg (25 of 71). A pulse rate of less than 100 was documented in 45.8% of all patients presenting with a systolic blood pressure less than 90 mm Hg (11 of 24). No increased mortality was seen in the patients who evidenced relative bradycardia. The effect of intraperitoneal bleeding on the normal tachycardic response to hemorrhage also was studied. After controlling for volume status using various operational definitions of shock, no statistically significant (P less than .01) difference in pulse rates was noted between patients with isolated penetrating abdominal trauma and isolated extremity trauma. This result suggests that the previously theorized vagal-mediated bradycardia unique to intraperitoneal bleeding may not exist.

Abdominal Injuries↗
PubMed1990

Methanol poisoning as a result of inhalational solvent abuse.

We report an unusual presentation of solvent abuse. A 17-year-old boy was brought to the emergency department after he inhaled fumes from a rag soaked with a carburetor cleaner containing toluene, methylene chloride, and methanol. Considered to be intoxicated from the acute effects of sniffing toluene or methylene chloride, the patient remained lethargic and ataxic despite removal from exposure and administration of supplemental oxygen. Subsequently, he was found to have a toxic serum methanol level (23 mg/dL). Toluene, methylene chloride, and methanol are widely used in industry and carry potential occupational risks for exposure. These agents are also found in many products available for home use. The toxicology and management of each of the agents in this exposure are discussed.

Adolescent↗
PubMed1990

Hypertrophic chondrocytes. The terminal stage of differentiation in the chondrogenic cell lineage?

Chondrocytes emerging in the limb or other locations during embryogenesis are currently considered terminally differentiated cells and thus represent the last stage of differentiation in the chondrogenic cell lineage. Most chondrocytes, however, undergo further major phenotypic changes during late embryogenesis and early postnatal life as they take part in the endochondral ossification process. During this process, "resting" chondrocytes first enter an active, proliferative phase and then develop into large, round hypertrophic chondrocytes with unique phenotypic traits. The question thus arises as to whether hypertrophic chondrocytes actually represent the terminal stage of differentiation in the chondrogenic lineage. To assess the developmental position of these cells along the lineage, we examined the expression of four genes encoding extracellular matrix components in chondrocytes undergoing endochondral ossification in chicken tibial growth cartilage. We found that the steady-state levels of mRNAs coding for proteoglycan core protein increased in regions of cartilage destined for endochondral ossification. Similarly, type II collagen gene expression increased markedly in proliferating chondrocytes and then returned to basal levels in hypertrophic chondrocytes. As revealed by in situ hybridization, type X collagen gene expression was undetectable in resting and early proliferating chondrocytes and was detectable in hypertrophic chondrocytes. Osteonectin synthesis appeared to characterize chondrocytes in the resting, proliferating, and hypertrophic zones of growth cartilage. The protein was scarce, however, and cell-associated in the former zones, although it was very abundant and matrix-associated in the hypertrophic zone. Clearly, the emergence of hypertrophic chondrocytes during endochondral ossification is accompanied by marked quantitative and qualitative changes in gene expression. Interestingly, these changes occur during or immediately after the period of active chondrocyte proliferation. On the premises of the cell lineage definition proposed by Holtzer, the above data suggest that the hypertrophic chondrocytes represent the terminal stage of differentiation in the chondrogenic cell lineage.

Animals↗
PubMed1990

Alcoholic ketoacidosis.

Alcoholic ketoacidosis is characterized by a metabolic acidosis with an elevated anion gap. It generally is seen in the chronic alcoholic patient who has recently gone on a "binge" that was terminated because of complaints such as nausea, vomiting or abdominal pain. Caloric intake is diminished. Treatment includes volume repletion and glucose administration. Morbidity and mortality usually result from intercurrent illness.

Alcoholism↗
PubMed1989

Ascorbic acid induces alkaline phosphatase, type X collagen, and calcium deposition in cultured chick chondrocytes.

During the process of endochondral bone formation, proliferating chondrocytes give rise to hypertrophic chondrocytes, which then deposit a mineralized matrix to form calcified cartilage. Chondrocyte hypertrophy and matrix mineralization are associated with expression of type X collagen and the induction of high levels of the bone/liver/kidney isozyme of alkaline phosphatase. To determine what role vitamin C plays in these processes, chondrocytes derived from the cephalic portion of 14-day chick embryo sternae were grown in the absence or presence of exogenous ascorbic acid. Control untreated cells displayed low levels of type X collagen and alkaline phosphatase activity throughout the culture period. However, cells grown in the presence of ascorbic acid produced increasing levels of alkaline phosphatase activity and type X collagen mRNA and protein. Both alkaline phosphatase activity and type X collagen mRNA levels began to increase within 24 h of ascorbate treatment; by 9 days, the levels of both alkaline phosphatase activity and type X collagen mRNA were 15-20-fold higher than in non-ascorbate-treated cells. Ascorbate treatment also increased calcium deposition in the cell layer and decreased the levels of types II and IX collagen mRNAs; these effects lagged significantly behind the elevation of alkaline phosphatase and type X collagen. Addition of beta-glycerophosphate to the medium increased calcium deposition in the presence of ascorbate but had no effect on levels of collagen mRNAs or alkaline phosphatase. The results suggest that vitamin C may play an important role in endochondral bone formation by modulating gene expression in hypertrophic chondrocytes.

Alkaline Phosphatase↗
PubMed1989

Cartilage-specific 5' end of chick alpha 2(I) collagen mRNAs.

Chondrocytes grown in suspension contain both type I and type II collagen mRNAs, yet synthesize only type II collagen. The inability of chondrocytes to synthesize the alpha 2 subunit of type I collagen, alpha 2(I), results from a severely reduced translation elongation rate (Bennett, V.D., and Adams, S.L. (1987) J. Biol. Chem. 262, 14806-14814). Furthermore, the alpha 2(I) collagen mRNAs from chondrocytes are translated inefficiently in vitro and appear slightly smaller than those from other cells (Focht, R.J., and Adams, S.L. (1984) Mol. Cell. Biol. 4, 1843-1852). These observations suggest that the reduced translation elongation rate may be due to an intrinsic property of the mRNAs. In this report we demonstrate that the alpha 2(I) collagen mRNAs from suspended chondrocytes are 120 bases shorter than those from other cells, and that the first 94 bases of the chondrocyte mRNAs differ from the corresponding region of the calvaria mRNAs. The unique 5' end of the chondrocyte alpha 2(I) collagen mRNAs accounts for their smaller size and may be responsible for the translation elongation defect. Interestingly, the alpha 2(I) collagen mRNAs from chondrocytes grown in monolayer, rather than in suspension, no longer display the cartilage-specific 5' end, suggesting that cell shape and/or adhesion may modulate the structure of the 5' end of the chondrocyte alpha 2(I) collagen mRNAs.

Animals↗
PubMed1989

The emergency management of a medicinal leech bite.

Leeches have been used as a medicinal remedy for years untold. Recently, there appears to have been a resurgence in the use of the medicinal leech, Hirudo medicinalis. Presented is the case of a patient who called the emergency department for advice concerning the management of a bleeding leech bite. We discuss briefly the pharmacologically active salivary contents of the leech and an approach to the emergency therapy of a medicinal leech bite.

Animals↗
PubMed1989

Collagen gene expression.

Collagens are extracellular matrix proteins that play important structural roles in many tissues and organs. Thirteen types of collagen, the products of 23 genes, have been described. Most of the collagen genes are developmentally regulated; a given tissue or cell type expresses only a subset of the collagen genes. Type I collagen, the most abundant protein in vertebrate connective tissues, is produced by most cells of mesenchymal origin except hyaline cartilage. Each tissue or cell type expresses the type I collagen genes at a characteristic rate. Maintenance of the normal synthetic rate appears to be important for preservation of normal tissue structure and function. Fibrotic lesions are characterized by increased production of type I collagen. The mechanisms that determine both the normal tissue-specific pattern of type I collagen gene expression and the elevated expression in fibrosis are complex. Both transcriptional and post-transcriptional mechanisms have been described, with modulation of mRNA stability being perhaps the most important post-transcriptional mechanism. Several sequences have been identified in the promoters of the type I collagen genes which are required for transcriptional activity; in addition, transcriptional enhances have been identified within the first introns of the genes. Type I collagen gene expression is also regulated both positively and negatively by a variety of exogenous factors, including inflammatory response mediators. The specific combination of such exogenous factors available in a given tissue probably determines the net rate at which the genes are expressed.

Collagen↗
PubMed1989

Effects of cell shape on type X collagen gene expression in hypertrophic chondrocytes.

During endochondral ossification, small flat resting and proliferating chondrocytes mature into large round hypertrophic chondrocytes that synthesize a unique collagen, type X. We have asked whether this change in cell shape during chondrocyte maturation regulates type X collagen gene expression, using immature chick vertebral chondrocytes grown in monolayer or in suspension. The freshly isolated chondrocytes contained no type X collagen RNA, but after 30 days of culture, both attached and suspended cells contained a similar large amount. However, in cells that were grown in monolayer and then resuspended three days before harvest, type X collagen gene expression increased a further 6 fold. These results suggest that the change from a flat to a round shape that occurs during chondrocyte maturation in vivo may be important for maximal expression of the type X collagen gene.

Animals↗
PubMed1988

The medicinal leech. A page from the annelids of internal medicine.

Leeches have been used in health care since ancient times by physician and layman alike. As just one of several methods of bloodletting, the leech became the focus of a science that included such subjects as indications, modes of attachment, complications, and relative contraindications. The popularity of leeching has varied immensely over the years. In the 19th century, this annelid saw its numbers decimated because of protean medicinal indications. The leech lost its hold on the practice of medicine in the early 20th century. Recently, the use of leeches has resurged in both the lay and the scientific communities.

Animals↗
PubMed1988

Clinical use of the olecranon-manubrium percussion sign in shoulder trauma.

We conducted a study to assess the efficacy of the use of osteophony in the evaluation of shoulder trauma. Evaluation of the shoulder includes the physical examination and often a radiographic series. We studied the usefulness of the olecranon-manubrium percussion (OMP) test, a physical diagnostic procedure performed in shoulder trauma. The bell of the stethoscope is placed over the manubrium, both elbows are flexed at 90 degrees, and the olecranon is percussed. In the normal examination with no disruption of bony conduction, both sides should produce a crisp equal sound. In the event of a dislocation or fracture with disruption of bony conduction, the affected side should be duller in pitch and intensity. We evaluated the utilization of the OMP test to assess its accuracy when used as a screening test for radiographs in conjunction with the physical examination and radiographic examination. Ninety-six patients were prospectively evaluated by the OMP test and also received radiographs. In those patients who had radiographic abnormalities, 40 of 47 (85.1%) had an abnormal OMP sign. In those patients without radiographic abnormalities, none had an abnormal OMP sign. In assessing anterior shoulder dislocations, 11 of 13 (84.6%) had an abnormal OMP sign (P less than .02). After relocation, 100% had a normal OMP sign. Of those with clavicular fractures, nine of nine (100%) had abnormal OMP signs (P less than .005). Of those with a fracture of the humerus, 16 of 20 (80%) revealed an abnormal OMP test (P less than .01). The test was not significant in assessing acromio-clavicular joint abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)

Emergencies↗
PubMed1987

Characterization of the translational control mechanism preventing synthesis of alpha 2(I) collagen in chicken vertebral chondroblasts.

Chondrogenesis, the differentiation of mesenchyme into cartilage, involves a transition from synthesis of type I to type II collagen. Chicken vertebral chondroblasts contain both type II and alpha 2 type I collagen RNAs but synthesize only type II collagen, suggesting the existence of translational discrimination between these RNAs. The experiments outlined in this report examine the translational control mechanism preventing the synthesis of alpha 2(I) collagen in chondroblasts. Specifically, the alpha 2(I) collagen RNA in the cytoplasm of mature chondroblasts does not appear to be sequestered in ribonucleoprotein particles that could prevent its translation in these cells. Instead, the RNA associates with an average of only three ribosomes; each of these ribosomes appears to be capable of forming at least one peptide bond. However, treatment of chondroblasts with low concentrations of cycloheximide, an elongation inhibitor, suggests movement of the ribosomes on the alpha 2(I) collagen RNA may be partially blocked, resulting in a severe reduction in the translation elongation rate. This translational mechanism may constitute an important regulatory function mediating the cessation of type I collagen synthesis during chondrogenesis.

Animals↗
PubMed1987

Modulation of fibronectin gene expression in chondrocytes by viral transformation and substrate attachment.

Chicken vertebral chondrocytes, which normally grow in suspension, synthesize large amounts of cartilage extracellular matrix proteins, but little fibronectin. We have analyzed the effects of both substrate attachment and transformation with a temperature-sensitive mutant of Rous sarcoma virus on fibronectin gene expression in these cells. Our experiments show that viral transformation increases fibronectin synthesis to a greater extent than substrate attachment. Furthermore, transformed chondrocytes have lost the ability to decrease fibronectin synthesis in response to suspension culture, suggesting that transformation alters the normal attachment-responsive control of fibronectin gene expression. Finally, infected substrate-attached chondrocytes shifted to the nonpermissive temperature for transformation use fibronectin RNA more efficiently in protein synthesis than cells grown under the other conditions, suggesting for the first time a role for translational control of fibronectin gene expression.

Animals↗
PubMed1986

Absence of a tachycardic response to intraperitoneal hemorrhage.

Five cases of intraperitoneal hemorrhage associated with hypotension and the lack of a tachycardic response are presented. All patients were young, previously healthy women without a history of myocardial disease. None of our patients fits into the category of "irreversible shock." Although relative bradycardia associated with hypotension is often considered a preterminal event, each of our patients recovered after laparotomy. In hypovolemic shock due to intraperitoneal bleeding, the lack of a tachycardic response may occur earlier and perhaps more often than has been suggested, and may delay definitive treatment by confusing the clinical picture. Orthostatic vital signs may be helpful in distinguishing those with true hypovolemia.

Adult↗