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Biomedical subjects

J T Smith

Publications and source records attributed to J T Smith.

At least 235 records · Page 13Linked to original sources
PubMedDate not supplied

Capillary zone electrophoresis of biological substances with fused silica capillaries having zero or constant electroosmotic flow.

A series of capillary surface modifications entailing multilayered coatings were introduced and evaluated in capillary zone electrophoresis of biological substances, e.g., proteins, peptides, oligosaccharides and nucleotides. In one set of surface modifications, large molecular weight hydroxypropyl cellulose afforded "zero" flow capillaries, which were used as precursors for developing anodal flow capillaries. When "zero" flow capillaries were further functionalized with a charge polyethyleneimine layer to which a top polyether layer was covalently attached, the resulting anodal electroosmotic flow was relatively weak due to the high viscosity of the coated wall imparted by the hydroxypropyl cellulose layer. Capillaries with relatively strong and constant anodal electroosmotic flow were best achieved when the inner capillary surface was first chemically derivatized with methylated (i.e., quaternarized) polyethyleneimine hydroxyethylated. This hydroxylated and permanently charged polymeric coating yielded constant anodal flow regardless of electrolyte pH. The hydroxyl groups of the charged polymeric coating permitted the covalent attachment of polyether chains, which minimized electrostatic interaction between the positive charges of the polymeric layer and oppositely charged biopolymers. Under these conditions, rapid transport of acidic biopolymers past the detection point in the separation capillary could be achieved, and relatively high plate counts were obtained.

Amino Acid Sequence↗
PubMedDate not supplied

Studies in capillary zone electrophoresis with a post-column multiple capillary device for fraction collection and stepwise increase in electroosmotic flow during analysis.

A new approach involving the stepwise increase in electroosmotic flow during analysis in capillary zone electrophoresis is introduced and evaluated in the rapid separations of proteins and peptides. The stepwise increase in electroosmotic flow is based on the principle of coupled capillaries in series having different flow characteristics, a concept that was introduced recently by our laboratory. To produce stepwise changes in electroosmotic flow during analysis, a post-column multiple capillary device, which allowed the switching between several coupled capillary systems, was designed and constructed in-house. The utility of the multiple capillary device was also demonstrated and extended to fraction collection of separated analytes in short capillary segments. The fraction collection in capillaries facilitated the quantitative transfer of the collected fractions to high performance liquid chromatography (HPLC) for further analysis or to mass spectrometry (MS) for structural determination. The off-line combination of capillary zone electrophoresis with HPLC or MS utilized commercial instruments without the need of expensive interfacing designs.

Amino Acid Sequence↗
PubMedDate not supplied

Placental and fetal growth retardation following partial progesterone withdrawal in rat pregnancy.

This study investigated placental expression of the two main isoforms of the progesterone receptor and the regulation of placental and fetal growth by progesterone over the final third of rat pregnancy, the period of maximal fetal growth. Expression patterns of mRNAs encoding the two major progesterone receptor isoforms (PR-A and PR-B) were measured by real-time RT-PCR in the two morphologically- and functionally-distinct regions of the placenta, the basal and labyrinth zones, at days 16 and 22 of pregnancy (term=day 23). PR-A and PR-B mRNA expression was extremely low in labyrinth zone on days 16 and 22, close to the limits of detection. In contrast, the basal zone exhibited much higher levels of mRNA expression for both PR-A (>10-fold higher than in labyrinth zone) and PR-B (3-fold higher at day 16). To assess the role of progesterone in placental growth, maternal progesterone was reduced from day 16 by ovariectomy with full estradiol replacement and partial progesterone replacement until day 22. Progesterone reduction lowered fetal (10%), whole placental (24%), basal zone (37%) and labyrinth zone (14%) weights at day 22 compared with sham-controls, whereas fetal and placental weights (both zones) were maintained in ovariectomised rats given full estradiol/progesterone replacement. The effects of progesterone withdrawal were not associated with changes in placental expression of either IGF-II or IGFBP-2, both important players in growth factor regulation of placental growth. Importantly, however, IGF-II expression remained elevated in the labyrinth zone but fell markedly in basal zone ( approximately 7-fold) between days 16 and 22 of normal pregnancy, consistent with the growth patterns of these two placental regions over this period.

Animals↗
PubMedDate not supplied

Combination trochanteric arrest and intertrochanteric osteotomy for Perthes' disease.

A significant complication associated with femoral varus osteotomy (FVO) is trochanteric overgrowth and concomitant abductor weakness. We identified 28 patients who underwent unilateral FVO for Perthes' disease, had a healed femoral head on their latest radiograph, and had at least 2.1 years of follow-up. The patients were divided into two groups; group 1: patients who did not receive prophylactic trochanteric arrest (TA) at the time of FVO; group 2: patients who did receive TA. Clinical parameters were quantified using objective measurements and a scoring system for reported symptoms. At postoperative follow-up, group 2 had greater articulotrochanteric distance (ATD), better range of motion, less abductor weakness, less pain, and superior activity levels. These differences were statistically significant. This study demonstrates that when properly performed with respect to indications and timing, the combination of TA and FVO provides an effective means of managing Perthes' disease when "head at risk" signs are present. The authors include a detailed discussion of surgical technique.

Child↗
PubMedDate not supplied

The predictive value of the development of the acetabular teardrop figure in developmental dysplasia of the hip.

We reviewed the radiographs of 72 hips, 47 with developmental dysplasia of the hip (DDH), and 25 normal hips, to determine the timing of the normal appearance of the acetabular teardrop figure and the value of teardrop development after reduction of the hip in predicting outcome. In normal hips, all children had a teardrop figure by age 18 months. In the 47 hips with DDH, no teardrop figure appeared until the hip was reduced. The DDH hips were divided into two groups based on the success of the initial reduction. By using statistical analysis, we found that the appearance of the acetabular teardrop within 6 months after reduction of the hip is strongly associated with a favorable long-term outcome. We believe that the appearance of the teardrop is the earliest radiographic sign that a stable, concentric reduction of the hip has been achieved.

Acetabulum↗
PubMedDate not supplied

Does pediatric orthopedic subspecialization affect hospital utilization and charges?

In the current climate of health care reform, there is a perception that overspecialization is responsible for increased medical costs. Few studies support the premise that high-quality surgical subspecialization improves the cost effectiveness of care. The purpose of this study was to compare hospital utilization and charges between a pediatric hospital staffed by pediatric orthopedic subspecialists and a community hospital system for the care of closed femur fractures and slipped capital femoral epiphysis (SCFE) in a pediatric population. We reviewed hospital charges and length-of-stay (LOS) data for all children treated for closed femoral shaft fractures and SCFE between 1992 and 1994 within the Intermountain Health Care System (IHC). Within the IHC, there are 23 community hospitals and one children's hospital (PCMC). Patients were matched for age and injury severity. Four of six orthopedic surgeons at PCMC are pediatric orthopedists, but none of the community orthopedists has subspecialty training in pediatric orthopedics. For closed femoral shaft fractures (n = 334), the average hospital charges were less (PCMC, $4,943/Other IHC, $9,031), and length of stay was shorter (PCMC, 2.81 days/Other IHC, 8.91 days) when the child was treated at the children's hospital by pediatric orthopedic subspecialists. For SCFE (n = 63), the average hospital charges were less (PCMC, $2,824/Other IHC, $3,544) and the length of stay was shorter (PCMC, 1.13 days/Other IHC, 1.64 days) at the children's hospital. These data suggest that hospital utilization and charges were significantly decreased if the care was provided by pediatric orthopedic subspecialists in a children's hospital.

Adolescent↗
PubMedDate not supplied

Combined adductor transfer, iliopsoas release, and proximal hamstring release in cerebral palsy.

Twenty-two patients with cerebral palsy (CP) and progressive lateral migration of the hip who underwent a combined adductor transfer, iliopsoas release, and proximal hamstring release were reviewed retrospectively. The average age at surgery was 4 years 9 months, and clinical and roentgenographic follow-up averaged 21.9 and 19.2 months, respectively. Ninety-five percent of the patients demonstrated an improved range of motion. Roentgenographic analysis showed a statistically significant decrease in the migration percentage and the acetabular angle and an increase in the CE angle. We concluded that this procedure adequately addressed this complex problem, thereby limiting the number of hospitalizations and surgical procedures for this patient group. Longer follow-up will be necessary to determine if these results are maintained with time.

Adolescent↗
PubMedDate not supplied

Transverse cervicopertrochanteric hip fracture.

A 3-year-old boy sustained a previously undescribed transverse hip fracture that involved the cervical, cervicotrochanteric, and intertrochanteric regions. The fracture was successfully treated with skeletal traction for 4 weeks using a Steinmann pin placed through the distal femoral metaphysis followed by spica cast immobilization. The 3-year follow-up examination demonstrated satisfactory growth and remodeling of the proximal femur with no evidence of osteonecrosis, premature physeal closure, or coxa vara.

Casts, Surgical↗
PubMedDate not supplied

Post-antibiotic effects of ofloxacin on Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, and Streptococcus pyogenes.

A viable counting technique was used to determine the post-antibiotic effect (PAE) of ofloxacin against four bacterial species, treated with either once of four times the minimum inhibitory concentration for 1 or 3 h. Similar to the results obtained previously with ciprofloxacin, ofloxacin gave PAE values with Escherichia coli, Staphylococcus aureus, and Streptococcus pyogenes. Cell division of Klebsiella pneumoniae was inhibited on removal of ofloxacin, but no clear PAE was demonstrated with this species because once replication recommenced, the mean generation times of drug-treated cultures were much shorter than those of untreated controls. Therefore, although the results obtained with ciprofloxacin and ofloxacin imply a consistency of PAE for 4-quinolones within a species, the response to DNA damage induced by 4-quinolones is multifaceted and species dependent. 4-quinolones inhibit both DNA replication and cell division, whilst at the same time stimulating DNA repair pathways. Thus, in some cases PAEs result from an increased post-treatment lag phase which may be followed by nearly normal multiplication, whereas in other cases a long lag may be followed by abnormally rapid cell division, with the generation times of treated cultures being shorter than those of corresponding drug-free controls. The PAE of a drug-induced lag may thus be masked by rapid cell division once growth resumes.

Colony Count, Microbial↗
PubMedDate not supplied

Post-antibiotic effects of cefdinir on Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus and Streptococcus pyrogenes.

The post-antibiotic effects (PAEs) of a new cephalosporin, cefdinir, were determined against a range of organisms using a viable counting technique. Cefdinir exerted considerable PAEs against Staphylococcus aureus and Streptococcus pyogenes, but no overall post-antibiotic inhibition of growth was detected against Escherichia coli or Klebsiella pneumoniae. Exposure to cefdinir made the gram-negative organisms susceptible to the washing procedure used for drug removal, but this was followed by rapid recovery of viability in drug-free broth.

Cefdinir↗
PubMedDate not supplied

Long-term stability of alignment in the monofixation syndrome.

From a collection of 328 patients with congenital esotropia, 80 patients were identified who had a minimum 4-year follow-up after surgical alignment within 8 prism diopters (pd) of orthophoria. These patients were subdivided into two groups: the M.S. group (38 patients) demonstrated the monofixation syndrome; the NO M.S. group (42 patients) did not have monofixation. The alignment of patients in each group was followed over time. After 17.5 years, 74% of patients in the M.S. group maintained alignment within 8 pd of orthophoria. In the NO M.S. group, only 45% were well aligned after 14 years. The mean time to loss of stability was significantly shorter for the NO M.S. group (P less than 0.005). Our findings suggest achievement of the monofixation syndrome improves but does not guarantee stability of ocular alignment.

Amblyopia↗