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Biomedical subjects

S Johnston

Publications and source records attributed to S Johnston.

At least 73 records · Page 4Linked to original sources
PubMed1995

High complete remission rates with primary neoadjuvant infusional chemotherapy for large early breast cancer.

PURPOSE: To investigate the efficacy of continuous infusion fluorouracil (5FU) with every-3-week epirubicin and cisplatin (ECF) as primary chemotherapy instead of immediate mastectomy for patients with large, potentially operable, breast cancer. PATIENTS AND METHODS: Fifty patients with large operable breast cancer, median tumor diameter 6 cm (range, 3 to 12), were treated with 5FU 200 mg/m2/d via a Hickman line using an ambulatory pump for 6 months with epirubicin 50 mg/m2 intravenously (IV) and cisplatin 60 mg/m2 IV every 3 weeks for eight courses. Subsequent surgery and/or radiotherapy was determined by clinical response. RESULTS: Forty-nine patients achieved an overall response (98%; 95% confidence interval [CI], 94% to 100%), including 33 complete clinical remissions (CRs) (66%; 95% CI, 53% to 79%). Only three patients (6%) still required mastectomy. Tumor cellularity was markedly reduced on repeat needle biopsy following 3 weeks of treatment in 81% of patients versus only 36% in similar patients after conventional chemotherapy (P < .002). Severe (World Health Organization [WHO] grade 3 to 4) toxicity was rare, with nausea/vomiting being the most common, occurring in 20% of patients. CONCLUSION: Primary infusional ECF appears to be more active on clinical and histopathologic grounds than conventional chemotherapy for large operable breast cancer and is well tolerated. This approach now merits randomized comparison to determine if high CR rates may translate into improved survival.

Adult↗
PubMed1994

Microvascular replantation of a completely avulsed scalp.

Total scalp avulsion is an unusual injury. To obtain good functional and cosmetic results, immediate revascularization using microsurgical techniques and replacement of the scalp in the correct anatomical position is the procedure of choice. This article describes a case report of successful replantation of a totally avulsed scalp from a 26-year-old male. Bilateral superficial temporal vessel anastomoses were performed using reversed autologous long saphenous vein grafts on the right side and direct repair on the left. Points of technique are discussed and the literature is reviewed.

Accidents, Occupational↗
PubMed1994

Evaluation of nested polymerase chain methods for the detection of human coronaviruses 229E and OC43.

Currently, the diagnosis of human respiratory coronavirus infection is either slow or insensitive. This paper describes nested polymerase chain reaction assays for the detection of human coronaviruses OC43 and 229E. The specificity and sensitivity of the assays have been determined and they have been applied to the detection of the viruses in nasal aspirates. These assays are more rapid and sensitive than cell culture and may replace the latter as the diagnostic method of choice.

Animals↗
PubMed1994

The need to retrieve the dropped stone during laparoscopic cholecystectomy.

The effect of bile and gallstones on the peritoneal cavity was evaluated in an experimental animal study. Ninety male Sprague-Dawley rats were randomly allocated to one of six groups (n = 15). Groups 1 to 3 received an intraperitoneal injection (2 mL) of saline, sterile bile, and infected bile, respectively. Groups 4 to 6 underwent a lower midline abdominal incision (3 to 5 mm). In groups 4 and 5, a single gallstone (< 3 mm diameter) was placed in the right upper quadrant and, after closure of the wound, the animals were injected with sterile bile and infected bile, respectively. Group 6 animals underwent laparotomy alone, followed by injection of sterile saline (2 mm). All animals were killed at 4 weeks and the peritoneal cavity was carefully examined. No intra-abdominal lesions were noted in groups 1 to 3. Adhesions were noted in 11 (73%) and 10 (67%) animals of groups 4 and 5, respectively. Two intra-abdominal abscesses were noted in group 4 animals. No intra-abdominal lesions were noted in any group 6 animals. This study suggests that bile in combination with gallstones in the peritoneal cavity is associated with an increased risk of intra-abdominal adhesion formation and possible abscess formation, and that every attempt should be made to retrieve stones lost during cholecystectomy.

Animals↗
PubMed1994

High resolution structures of the 4-4-20 Fab-fluorescein complex in two solvent systems: effects of solvent on structure and antigen-binding affinity.

Three-dimensional structures were determined for three crystal forms of the antigen binding fragment (Fab) of anti-fluorescein antibody 4-4-20 in complex with fluorescein. These included 1) a triclinic (P1) form crystallized in 47% (v/v) 2-methyl-2,4-pentanediol (MPD); 2) a triclinic (P1) form crystallized in 16% (w/v) poly(ethylene glycol), molecular weight 3350 (PEG); and 3) a monoclinic (P21) form crystallized in 16% PEG. Solvent molecules were added to the three models and the structures were refined to their diffraction limits (1.75-A, 1.78-A, and 2.49-A resolution for the MPD, triclinic PEG, and monoclinic PEG forms, respectively). Comparisons of these structures were interesting because 4-4-20 exhibited a lower antigen-binding affinity in 47% MPD (Ka = 1.3 x 10(8) M-1) than in either 16% PEG (Ka = 2.9 x 10(9) M-1) or phosphate-buffered saline (Ka = 1.8 x 10(10) M-1). Even though the solution behavior of the antibody was significantly different in MPD and PEG, the crystal structures were remarkably similar. In all three structures, the fluorescein-combining site was an aromatic slot formed by tyrosines L32, H96, and H97 and tryptophans L96 and H33. In addition, several active site constituents formed an electrostatic network with the ligand. These included a salt link between arginine L34 and one of fluorescein's enolate oxygen atoms, a hydrogen bond between histidine L27d and the second enolic group, a hydrogen bond between tyrosine L32 and the phenylcarboxylate group, and two medium range (approximately 5 A) electrostatic interactions with lysine L50 and arginine H52. The only major difference between the triclinic MPD and PEG structures was the degree of hydration of the antigen-combining site. Three water molecules participated in the above electrostatic network in the MPD structure, while eight were involved in the PEG structure. Based on this observation, we believe that 4-4-20 exhibits a lower affinity in MPD due to the depletion of the hydration shell of the antigen-combining site.

Amino Acid Sequence↗
PubMed1993

Transgenic corn plants expressing MDMV strain B coat protein are resistant to mixed infections of maize dwarf mosaic virus and maize chlorotic mottle virus.

The maize dwarf mosaic virus strain B (MDMV-B) coat protein (cp) gene was cloned into a monocot expression cassette and introduced into sweet corn cell suspension cultures via particle bombardment or electroporation. Transformed cells were selected on culture media containing 300 mg/l kanamycin, and plants were regenerated. Cells from all transformed lines expressed the cp gene; and one transgenic line synthesized approximately 100-200 micrograms MDMV-cp per gram fresh weight. Plants regenerated from this line were challenged with a virus inoculum concentration adjusted to produce symptoms in nontransgenic controls at six days post inoculation. In growth chamber studies, the presence of the MDMV-cp provided resistance to inoculations with MDMV-A or MDMV-B and to mixed inoculations of MDMV and maize chlorotic mottle virus.

Base Sequence↗
PubMed1993

Renal function changes in microalbuminuric normotensive type II diabetic patients treated with angiotensin-converting enzyme inhibitors.

OBJECTIVE: To determine the effects of captopril on microalbuminuria and renal function in normotensive type II diabetic patients. RESEARCH DESIGN AND METHODS: A total of 26 patients were randomized in two homogeneous groups for clinical and analytical data in a 6-mo follow-up study. Group A received captopril (initial dose: 12.5 mg daily, increased according to tolerance); group B was untreated. RESULTS: Microalbuminuria decreased only in the treated group at 6 mo (P = 0.044) and a significant (P = 0.027) mean percentage change on microalbuminuria excretion between the groups was observed. Filtration fraction decreased in group A (baseline: 0.23 +/- 0.03; 6 mo: 0.22 +/- 0.04) and increased in group B (baseline: 0.22 +/- 0.04; 6 mo: 0.25 +/- 0.04) with a significant mean percentage change between the groups at 6 mo (P = 0.032). The mean percentage change in microalbuminuria was significantly correlated with a mean percentage change in diastolic blood pressure throughout the trial. Neither metabolic control nor sodium or protein intake changed in either group during the trial. CONCLUSIONS: These results suggest that captopril can help arrest microalbuminuria in normotensive type II diabetic patients, with a decrease in diastolic blood pressure and filtration fraction after a 6-mo treatment.

Albuminuria↗
PubMed1993

Communication intervention for persons with severe and profound disabilities.

Traditionally, communication interventionists focused on teaching a beginning repertoire of communicative behavior, once learners with severe to profound disabilities had emitted intentional behavior. Increasingly, interventionists are recognizing that valuable opportunities may be lost if intervention does not begin at an earlier point. In part, intervention strategies at increasingly earlier points have resulted from a prevailing change from semantically-focused intervention logic to pragmatic, interaction-focused intervention logic. At the same time that intervention content has increasingly focused on pragmatics, there has been a wealth of information addressing the social functions served by repertoires of simple idiosyncratic (as well as socially unacceptable) behavior. The increasing availability of augmentative and alternative communicative options has provided an extensive array of motorically simple strategies to exert significant control and influence over one's environment. We have long since passed the need to demonstrate that persons with severe disabilities can be taught a repertoire of communicative functions. However, we have not been as successful in demonstrating that the communicative behavior taught is well maintained solely in the presence of natural maintaining contingencies. Nor have we adequately demonstrated that established repertoires are sufficiently generalized. Most recently, interventionists have begun to focus on more efficient strategies to use in the selection of the most critical teaching instances to teach a new communicative response. Additionally, interventionists are considering response efficiency as an important variable in determining the likelihood that a learner will choose to emit members of his or her communicative repertoire. There appears to be a consensus among those who currently serve individuals with severe disabilities that inclusion represents an attainable objective for students with even the most severe disabilities. Unfortunately, it is not clear that either special or regular educators are being adequately prepared to accomplish included placements. There remains a significant need to recognize those aspects of best practice which must be further explored in regular education settings. What once were considered best practice methods may not meet the test of social validity and be considered best practices in regular classrooms. The vast majority of intervention research has selected a fairly narrow communicative form or function to teach. Increasingly, information on maintenance and generalization is considered. However, often the periods sampled postacquisition are very modest. Among the plethora of available communication intervention curricula, there are virtually none that have taken a learner from a point of engaging in no intentional communicative behavior to the establishment of an effusive repertoire of communicative functions and corresponding vocabulary.(ABSTRACT TRUNCATED AT 400 WORDS)

Adolescent↗
PubMed1992

Cadmium effects on bone metabolism: accelerated resorption in ovariectomized, aged beagles.

The purpose of this study was to evaluate, in an animal whose skeleton is comparable to humans, the combined effects of estrogen depletion and Cd exposure on bone resorption by monitoring skeletal release of 45Ca and to determine whether Cd-induced bone resorption occurred independent of osteotropic hormone changes and renal dysfunction. Cd exposure following ovariectomy or sham surgery was for 7 months: 1 month by oral ingestion of capsules (1, 5, 15, 50 ppm) and 6 months via drinking water (15 ppm). Serum and fecal 45Ca were increased at 1 week following ovariectomy (OV) (54 +/- 9% and 122 +/- 40%, respectively), but this response was attenuated by 2 weeks. Five of seven exposed dogs had increased serum and fecal 45Ca during the 50-ppm Cd capsule period (15-40% and 15-190%, respectively). Serum 45Ca levels in OV/+Cd dogs showed a significant and consistent increase within 1 week of initiating each of three separate Cd.H2O exposure cycles. Blood Cd levels increased over time from 2 to 15 micrograms/l, coinciding with the elevated serum 45Ca concentrations. No correlation was observed between serum 45Ca increases and parathyroid hormone, 1,25-(OH)2-vitamin D, or calcitonin. No effects of ovariectomy and/or Cd were observed in total serum Ca, calciotropic hormone concentrations, serum or urinary phosphorus and creatinine, creatinine clearance, or urinary specific gravity. Urinary Cd concentrations ranged from 7 to 50 micrograms/l in exposed dogs but were not detectable in nonexposed dogs. Urinary protein concentrations showed no differences between groups. Cd increased bone resorption (skeletal 45Ca release) in ovariectomized and sham-operated dogs without renal dysfunction or calciotropic hormone interaction. Based on our results, Cd is an exogenous factor which exacerbates bone mineral loss in postmenopausal osteoporosis.

Aging↗
PubMed1992

Acute hypoxemic respiratory failure in infants and children: clinical and pathologic characteristics.

OBJECTIVE: To examine the clinical and pathologic features of acute hypoxemic respiratory failure in children. DESIGN: Retrospective review of medical records and pathologic material during a 44-month period. SETTING: Multidisciplinary pediatric ICU. PATIENTS AND METHODS: With the assistance of a computerized database, the medical records of 2,254 pediatric ICU admissions were evaluated to identify children with respiratory failure. Children with acute hypoxemic respiratory failure who met the following definition were selected for inclusion: a) PaO2 less than 75 torr (less than 10.0 kPa) with an FIO2 of greater than 0.5; b) diffuse bilateral infiltrates on chest radiograph; and c) exclusion of cardiogenic pulmonary edema clinically or by pulmonary artery catheterization. Patients were excluded if they did not receive tracheal intubation and assisted ventilation. The medical records were reviewed for demographic, clinical, and physiologic information. Pathologic findings from autopsy or lung biopsy were also reviewed. Patients were placed in one of six groups based on their underlying disorder. In addition, the presence of neutropenia, septic shock, or a history of bone marrow transplantation was noted as a coexisting condition. MAIN RESULTS: A total of 100 acute hypoxemic respiratory failure patients were identified (4.4% of all 2,254 pediatric ICU admissions; 50 male, 50 female). Mean age was 6.0 +/- 5.4 (SD) yrs (range 1 month to 18 yrs). The overall mortality rate was 72%. The mortality rate was not affected by the underlying disorder, but it was higher in the presence of septic shock (80% vs. 58%; odds ratio 2.8), neutropenia (88% vs. 64%; odds ratio 4.0), and bone marrow transplantation (95% vs. 66%; odds ratio 10.4). When multivariate regression analysis was performed using all coexisting conditions, human immunodeficiency virus status, and patient gender, only a history of bone marrow transplantation and gender appeared to affect outcome. Oxygenation ratio (PaO2/FIO2), alveolar-arterial oxygen tension difference, duration of exposure to high levels of oxygen, and airway pressure measurements indicated more severe derangement of pulmonary function in those patients who died. Cardiac function was similar in survivors and nonsurvivors. Respiratory failure occurred in 32 children with severe neutropenia (mean absolute neutrophil count 55 +/- 101 cells/mm3), including 16 children with an absolute neutrophil count of 0. Pulmonary tissue from 37 children was studied. Diffuse alveolar damage was observed in 24%; morphologic evidence of infectious pneumonitis was encountered in an additional 41%. CONCLUSIONS: Children with acute hypoxemic respiratory failure represent a heterogeneous subset of patients. In our group of patients, infectious pneumonitis was more commonly encountered than diffuse alveolar damage. The mortality rate of children with acute hypoxemic respiratory failure has not improved since 1980.

Acute Disease↗