Biomedical subjects
Publications and source records attributed to S M Smith.
We describe two patients with left ventricular diverticula which were seen during routine left ventriculography. The diverticula were probably incidental findings and asymptomatic. A review of the literature to determine associated cardiac and extra-cardiac abnormalities and related morbidity and mortality with emphasis of potential treatment strategies is presented.
To determine the utility of 4.1 French (F) catheters in diagnosing coronary artery disease, 50 patients were randomized to 4.1F Multipurpose or Judkins catheters utilizing the percutaneous right brachial approach. The randomized 4.1F tip shape catheter completed the procedure in 40% of the patients, and overall the 4.1F catheters completed the catheterization in 72% of the cases. With excessive or prolonged manipulation, the catheters were noted to kink and soften and required replacement for a catheter of similar or larger size. In 28% of the cases, larger F sizes (5F and 6F) were used to complete the procedure. There was 1 (2%) procedural complication. The total procedural success (accounting for all F sizes) without clinical complication was 98%. There was no difference between the 4.1F Judkins or Multipurpose catheter shapes for coronary arteriography by either qualitative or quantitative angiographic analysis. Left ventricular opacification was improved with the 4.1F Pigtail vs. the 4.1 Multipurpose by qualitative angiographic analysis. When the 4.1F angiograms were compared by quantitative angiography in blinded, but not randomized fashion to angiograms performed with 6F Judkins catheters, there was improved opacification of the LAD and diastolic frame of the left ventriculogram with the larger catheter. This difference was not noted with qualitative angiography. This study indicates that 4.1F catheters can be utilized from the right brachial approach for the diagnosis of coronary artery disease, thus avoiding the need for supine bedrest associated with routine femoral artery catheterization while maintaining diagnostic accuracy.
During the process of endochondral bone formation, the maturing chondrocyte exhibits profound changes in energy metabolism. To explore the mechanism of energy conservation in cartilage we examined the expression of creatine kinase, an enzyme that catalyzes the formation of ATP in tissues under oxygen stress. Measurement of creatine kinase activity and cytochemical assessment of enzyme distribution clearly showed that the level of enzyme activity was related to chondrocyte maturation. Thus, as the cells hypertrophied, there was a progressive increase in creatine kinase activity. Similarly, an elevation in creatine kinase activity was noted in chondrocyte cultures as the cells assumed an hypertrophic state. When cartilage calcification was disturbed by rickets, there was a decrease in enzyme activity in the hypertrophic region. Studies were performed to examine the creatine kinase isozyme profile of cells of the epiphysis. In resting and proliferating cartilage, the isoform was MM. In hypertrophic cartilage, the predominant isoforms were MB and BB. In terms of the creatine phosphate content, the highest values were seen in the proliferative region; lower amounts were present in hypertrophic and resting cartilage; and no creatine phosphate was detected in calcified cartilage. These data suggest that turnover of creatine phosphate is greatest in the mineralized region of the epiphysis. The results of these investigations point to creatine kinase as being under developmental control. The activity of the enzyme in cartilage cells should serve as a marker of developmental events associated with chondrocyte proliferation, hypertrophy, and mineralization.
The basal lamina protein, laminin, has been shown to promote migration and proliferation of cultured skeletal myoblasts, resulting in increased myotube formation. However, skeletal myotubes adhere poorly to a laminin substrate, and long-term cultures of skeletal myotubes on laminin have not been achieved. We have found that cultured satellite cells from bupivacaine-damaged rat skeletal muscle actively proliferate and differentiate on a diluted Matrigel substrate composed of laminin, type IV collagen, heparan sulfate proteoglycan, and entactin. Myotubes cultured on diluted Matrigel are contractile and have never been observed to detach from the culture dish; rather, myotubes generally atrophy after 2-3 weeks in culture. Antibodies directed against the various protein components of Matrigel were used to determine the role of each component in enhancing muscle differentiation. Anti-laminin impaired satellite cell adhesion, whereas antibodies against either type IV collagen or heparan sulfate proteoglycan had no effect. Anti-entactin did not inhibit attachment, proliferation, or fusion of cultured satellite cells; however, myotubes exposed to anti-entactin failed to adhere to the culture dish after spontaneous myotube contractions began. We conclude that entactin is responsible for long-term maintenance and maturation of contractile skeletal myotubes on a diluted Matrigel substrate. This is the first study to assign a biological function for entactin in myogenesis.
A case of aggressive lupus nephritis in a pediatric renal transplant patient is described. She initially presented with end-stage glomerulonephritis for which an underlying etiology could not be determined. Ten months after cadaveric renal transplantation, systemic lupus erythematosus was diagnosed, when she developed diffuse proliferative glomerulonephritis in association with antinuclear antibody, anti-double-stranded DNA antibody and extrarenal manifestations of lupus. It is plausible that she developed recurrent rather than de novo lupus nephritis following transplantation. Reactivation of lupus nephritis in a renal transplant is unusual in adults, and is previously unreported in children.
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Floral initiation can be analyzed from a developmental perspective by focusing upon how developmental fates are imprinted, remembered, and expressed. This is not an altogether new perspective, since people studying flowering have been concerned for a long time with the commitment of meristems to form flowers and the morphological, cellular, and molecular changes associated with this commitment. What is novel is the emphasis on developmental states as opposed to physiological processes. This developmental focus indicates that there appear to be at least three major developmental states that are acquired and expressed in the process of a meristem initiating floral morphogenesis. The meristem cells must first become competent to respond to a developmental signal that evokes them into a florally determined state. The leaves are the usual source of this signal and a specific leaf may or may not have the capacity to be inductively active. When a leaf does develop the capacity for inductive activity, this capacity is usually correlated with the ontogeny of the leaf. Inductive activity, however, may be continually expressed as in some day-neutral plants or may be latent as in plants where the photoperiod is the external cue for activity. Competent shoot apical meristems respond to inductive leaf signal by being evoked into a florally determined state. Under permissive conditions this florally determined state is expressed as the initiation of floral morphogenesis. Many mechanisms have evolved to regulate entry into and expression of these developmental states. As we learn more about the developmental states associated with flowering and how they are acquired and expressed, we will understand better how the various patterns of flowering are related to one another as well as which developmental processes are common to all angiosperms.
The stability of the florally determined state in terminal and axillary buds of two tobacco cultivars was studied. We used Hicks and Hicks Maryland Mammoth, near-isogenic cultivars of Nicotiana tabacum differing at the recessive maryland mammoth locus which confers short-day behavior. The experimental design consisted of growing plants in short-day conditions and subjecting them to three bioassays in long-day conditions: in vitro culture of apices consisting of meristems and three to four leaf primordia; rooting of buds consisting of meristems and 8 to 12 leaves, leaf primordia, and internodes; and release from apical dominance of axillary buds in situ. Cultured terminal and axillary apices expressed floral determination, indicating that meristems can be florally determined. Two lines of evidence indicate that rooting destabilizes an already acquired florally determined state: cultured apices from both axillary and terminal buds produced fewer nodes after excision than homologous buds which were rooted; and a lower percentage of rooted axillary buds from Hicks Maryland Mammoth plants expressed floral determination than did homologous axillary buds grown out in situ in noninductive conditions. Rooted buds from the two genotypes expressed floral determination at different frequencies, but produced abnormal inflorescences at similar frequencies, indicating that roots and the maryland mammoth allele influence common as well as unique processes associated with floral determination.
Vascular prosthetic infection may be underrecognized when identified by standard culture techniques. Improved microbiologic methodology may enhance detection of bacteria in prosthetic graft specimens, and thus may alter clinical decisions. Quantitative culture techniques were employed to compare three methods of enhancing bacterial recovery from Dacron graft cylinders seeded with commonly encountered bacterial pathogens. Methods included: (1) ultrasonic bath treatment, (2) direct ultrasonic disruption, and (3) agitation on a Vortex mixer. Ultrasonic bath treatment released bacteria with colony counts that were consistently greater by 1 log than direct ultrasonic disruption and Vortex agitation. Direct ultrasonic disruption at high energy levels selectively killed gram-negative bacteria by as much as a 4 log decrease in viable organisms. Agitation (Vortex mixing) of the specimen produced the lowest counts among the three methods tested. These data would indicate that a 5-min ultrasonic bath treatment was the optimal method of preparation of vascular prostheses for bacterial culture.
Geschwind and colleagues discussed associations among learning disorders, immune disorders and non-right-handedness. In this study, we examined the associations between reading disability (RD) and both immune disorders (ID) and non-right-handedness (NRH) in family and twin samples (total N = 1731 cases) identified through an RD proband. We also conducted co-segregation analyses to ascertain the degree to which NRH, ID and RD were biologically related. There was little evidence for an overall association between RD and NRH. There was not convergent evidence across all four samples for an association between RD and ID, although we did find an association between RD and ID in two of four samples. Nor was there strong support for a subtype where RD and NRH, or RD and ID, co-segregate in families. These data suggest that the associations postulated by Geschwind and colleagues are not robust in RD samples, although we cannot completely rule out the possibility of an RD plus ID subtype.
We investigated the hypothesis that alcohol-induced changes of the immune system result in IgA nephropathy (IAN). Wistar rats were infused with liquid diet containing alcohol: "alcoholics." Control rats received an isocaloric diet with glucose instead of alcohol. IAN was diagnosed by mesangial IgA deposition. When compared to controls, serum IgA in alcoholic rats with IAN had a fourfold increase and a twofold increase in alcoholics without IAN. The intestinal lamina propria showed overall lymphocyte depletion in alcoholic rats. The decrease was not uniform for all the lymphocyte subgroups: it resulted in a relative increase in IgA-B cells in alcoholic rats with IAN but not in alcoholic rats without IAN. No significant differences were observed between alcoholic and control rats in the percentages of spleen lymphocyte subtypes. We suggest that dysfunction of the mucosal immune system may be related to the induction of IAN in chronic alcohol consumption.
The attainable inhibitory ratios (AR) for oral antibiotics were calculated by using literature reports of concentrations attained in respiratory secretions for amoxicillin-clavulanic acid (AMX/CA), ofloxacin (OFL), L-ofloxacin (L-OFL), cefuroxime (CEFU), ciprofloxacin (CIP), and enoxacin (ENO), and using microdilution minimum inhibitory concentration data of these antimicrobials against the common bacterial respiratory pathogens. AR of each antibiotic against the pathogens was expressed as multiples of the MICs achieved at the respiratory site. Bacteria tested included Staphylococcus aureus, group-A and group-B streptococci, Viridans streptococci, Streptococcus pneumoniae, Brahamella catarrhalis, Klebsiella pneumoniae, Eikenella corrodens, Haemophilus influenzae, H. parainfluenzae, Pseudomonas aeruginosa, and Legionella pneumophila. The antimicrobials with the narrowest spectrum of activity were amoxicillin-clavulanic acid and cefuroxime which had high attainable inhibitory ratios only against Gram-positive cocci. Ofloxacin and L-oflaxacin were among the quinolones with the highest overall ARs against respiratory pathogen, including, L. pneumophila, H. influenzae, and B. catarrhalis. All agents showed no, or inadequately low ARs for P. aeruginosa.
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Patients with fungemia, mainly due to Candida albicans, had cultures repeated from arterial and venous sites to determine yeast cell clearance during fungemia. Of the 48 patients, 37 had repeat positive cultures (36 arterial and venous samples; one venous culture). Additionally, 24 patients had arterial and venous samples cultured quantitatively. An average of 9.1 colony forming units (CFU) ml-1 was isolated from arterial samples and 5.5 CFU ml-1 from venous samples (60% of arterial, P < 0.01). This suggest that arterial fungal densities exceed venous densities and that peripheral tissues clear 40% of yeasts.
Gonotrophic-age structure of a population of Aedes provocans (Walker) and nectar sources used by adults were studied for 2 yr at a field site near Belleville, Ontario, Canada. Females emerged during a short period, and aging of the population was highly synchronous. Complete parity of the population was achieved within about 17 d in 1978 and 27 d in 1979. Some females completed as many as four gonotrophic cycles. This synchronous pattern of population aging is compared with patterns in other species of snow-melt Aedes, which typically age much more gradually. The pattern of synchronous aging permitted estimation of daily mortality rates from an index of population size derived from human-bait catches; peaks in the biting index were related to each gonotrophic cycle in the population. Nectar sources for adults were ranked according to abundance and the extent to which they were used by Ae. provocans, permitting a coarse, semiquantitative estimate of preferences. Ae. provocans obtained nectar from the extrafloral nectaries of one species and the floral nectaries of 19 species of angiosperms. Shrubs and trees, especially of the Rosaceae (primarily species of Prunus), were particularly important as nectar sources and bloomed concurrently with the appearance of nulliparous females. Sharp declines in the population of Ae. provocans were associated with the cessation of blooming of these plant species. It is hypothesized that the highly synchronous pattern of gonotrophic aging in Ae. provocans was attributable, in part, to the ready availability of nectar sources and bloodmeal hosts near breeding sites.
The interactive effect of iron deficiency and dietary carbohydrate type on growth and thyroid hormone status of Sprague-Dawley rats was studied. Rats were fed either an iron-adequate (approximately 35 micrograms Fe/g) or an iron-deficient (less than 3 micrograms Fe/g) diet that contained 70% carbohydrate. The carbohydrate sources were 100% cornstarch (STARCH), 85.7% cornstarch and 14.3% sucrose (STARCH/SUCR), 71.4% cornstarch, 14.3% sucrose and 14.3% dextrin (DEXTRIN), or 100% sucrose (SUCROSE). After 4 wk, iron-deficient rats weighed less than the iron-adequate rats and were severely anemic. Total food intake was lower in iron-deficient than in iron-adequate animals; it was also significantly lower in SUCROSE-fed animals relative to other carbohydrate groups. Plasma glucose concentrations were significantly higher in iron-deficient rats than in iron-adequate rats, but plasma thyroid hormones, thyroxine and triiodothyronine, and liver thyroxine monodeiodinase activity were lower. Deiodination of reverse triiodothyronine in liver was unaffected by iron deficiency regardless of carbohydrate treatment. The STARCH-fed animals had higher rates of hepatic thyroxine monodeiodinase activity than rats fed the other dietary carbohydrates. The two main conclusions from this study are that thyroid hormone metabolism is altered by iron deficiency regardless of food intake and that the best purified rodent diet for this type of study would contain a mixture of carbohydrate types to avoid the stimulation of thyroxine monodeiodinase by a 70% cornstarch diet.
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