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Biomedical subjects

T J Johnson

Publications and source records attributed to T J Johnson.

At least 19 recordsLinked to original sources
PubMed2003

Identification by subtractive suppression hybridization of bacteria-induced genes expressed in Manduca sexta fat body.

Insect immune processes are mediated by programs of differential gene expression. To understand the molecular regulation of the immune response in the tobacco hornworm, Manduca sexta, the relevant subset of differentially expressed genes of interest must be identified, cloned and studied in detail. In this study, suppression subtractive hybridization, a PCR-based method for cDNA subtraction was performed to identify mRNAs from fat body of immunized larvae that are not present (or present at a low level) in control larvae. A subtracted cDNA library enriched in immune-inducible genes was constructed. Northern blot analysis of a sample of clones from our subtracted library indicated that >90% of the clones randomly selected from the subtracted library are immune inducible. Sequence analysis of 238 expressed sequence tags (ESTs) revealed that 120 ESTs, representing 54 distinct genes or gene families, had sequences identical or similar to previously characterized genes, some of which have been confirmed to be involved in innate immunity. These ESTs were categorized into seven groups, including pattern recognition proteins, serine proteinases and their inhibitors, and antimicrobial proteins. 112 ESTs, about 47.5% of the library, showed no significant similarity to any known genes. The sequences identified in this M. sexta library reflect our knowledge of insect immune strategies and may facilitate better understanding of insect immune responses.

Adipose Tissue↗
PubMed2003

Resistance to serum complement, iss, and virulence of avian Escherichia coli.

Control of avian colibacillosis is hampered by lack of easily identifiable markers for virulent Escherichia coli. Resistance to serum complement appears to be a widespread trait of virulent avian E. coil, suggesting that bacterial factors promoting survival in serum may be useful in discriminating between virulent and avirulent isolates. Such distinguishing factors may prove useful in diagnostic protocols or as targets in future colibacillosis control protocols. Interestingly, the factors responsible for resistance to complement differ in the E. coli isolated from mammalian and avian hosts, which may reflect differences in the nature of avian and mammalian colibacillosis. In some cases, genetic determinants for serum complement resistance in avian E. coli are found on aerobactin- or Colicin V-encoding plasmids. One such gene, iss, first described for its role in the serum resistance associated with a ColV plasmid from a human E. coli isolate, occurs much more frequently in isolates from birds with colibacillosis than in faecal isolates from healthy birds. Efforts to identify the genomic location of iss in a single, virulent avian E. coli isolate have revealed that it occurs in association with several purported virulence genes, all linked to a large conjugative R plasmid. At this time, it is not known whether iss merely marks the presence of a larger pathogenicity unit or is itself a contributor to virulence. Nevertheless, the presence of the complement-resistance determinant, iss, may be a marker of virulent avian E. coli exploitable in controlling avian colibacillosis.

Animals↗
PubMed2001

Laser modification of preformed polymer microchannels: application to reduce band broadening around turns subject to electrokinetic flow.

A pulsed UV excimer laser (KrF, 248 nm) was used to modify the surface charge on the side wall of hot-embossed microchannels fabricated in a poly(methyl methacrylate) substrate. Subablation level fluences, less than 2,385 mJ/cm2, were used to prevent any changes in the physical morphology of the surface. It is shown that the electroosmotic mobility, induced by an electric field applied along the length of the channel, increases by an average of 4% in the regions that have been exposed to UV laser pulses compared to nonexposed regions. Furthermore, application of UV modification to electroosmotic flow around a 90 degrees turn results in a decrease in band broadening, as measured by the average decrease in the plate height of 40% compared to flow around a nonmodified turn. The ability to modify the surface charge on specific surfaces within a preformed plastic microchannel allows for fine control, adjustment, and modulation of the electroosmotic flow without using wall coatings or changing the geometry of the channel to achieve the desired flow profile.

Journal Article↗
PubMed2001

Imaging of electroosmotic flow in plastic microchannels.

We have characterized electroosmotic flow in plastic microchannels using video imaging of caged fluorescent dye after it has been uncaged with a laser pulse. We studied flow in microchannels composed of a single material, poly(methyl methacrylate) (acrylic) or poly(dimethylsiloxane) (PDMS), as well as in hybrid microchannels composed of both materials. Plastic microchannels used in this study were fabricated by imprinting or molding using a micromachined silicon template as the stamping tool. We examined the dispersion of the uncaged dye in the plastic microchannels and compared it with results obtained in a fused-silica capillary. For PDMS microchannels, it was possible to achieve dispersion similar to that found in fused silica. For the acrylic and hybrid microchannels, we found increased dispersion due to the nonuniformity of surface charge density at the walls of the channels. In all cases, however, electroosmotic flow resulted in significantly less sample dispersion than pressure-driven flow at a similar velocity.

Journal Article↗
PubMed2000

Estradiol and pesticide methoxychlor do not exhibit additivity or synergism in the reproductive tract of adult ovariectomized mice.

The pesticide methoxychlor (MXC) is a DDT substitute that exhibits estrogenic activities in different animals. To determine whether there is synergism between purified MXC and a natural estrogen, ovariectomized adult mice received 3 daily intraperitoneal doses of either 2.5 or 25 ng estradiol-17beta or 0.125, 0.25, or 0.5 mg MXC administered separately or in combination. The mice were sacrificed on d 4. Reproductive tracts were excised, weighed, and one uterine horn was flushed with phosphate-buffered saline, with the fluid electrophoresed on a one-dimensional sodium dodecyl sulfate polyacrylamide gel to determine albumin content. The remaining uterine horn and vagina were prepared for histology and epithelial height measurements. Estradiol significantly increased reproductive-tract weights. Although both the vaginal and uterine epithelial heights increased in mice treated with combined chemicals when compared to controls, the organ histology did not show increased stimulation. Albumin content was significantly elevated only in the estradiol group. The present data do not suggest that either synergism or additive effects occurred between an estrogen and MXC in the reproductive tracts of ovariectomized adult mice. In fact, combining MXC with estradiol suggests inhibitory effects.

Albumins↗
PubMed2000

Busy physicians and preventive services for adults.

OBJECTIVE: To study the relationship between overall productivity and the rates at which primary care physicians, in a fee-for-service setting, deliver or prescribe preventive services to adult patients. PATIENTS AND METHODS: The charts of 452 adult patients treated by 8 family practitioners and 5 internists in a fee-for-service practice setting were randomly selected and abstracted for provision of 10 preventive services over a 27-month period. The percentage of eligible patients screened for each service was correlated with the production of each physician measured in relative value units (RVUs). RESULTS: The correlation coefficient between RVUs and the aggregate of the 10 services was 0.23 (95% confidence interval [CI], -0.36 to 0.70). The individual correlation coefficients between RVUs and 9 of the 10 preventive services ranged from -0.05 to 0.43. For cervical cancer screening, however, the correlation coefficient was -0.72 (95% CI, -0.91 to -0.24). CONCLUSION: With the exception of screening for cervical cancer, the data presented in this study do little to support physicians' common belief that lack of time is the reason they are unable to incorporate prevention strategies into their clinical practice.

Adult↗
PubMed1999

Oral contrast solution and computed tomography for blunt abdominal trauma: a randomized study.

HYPOTHESIS: Oral contrast solution (OC) is unnecessary in the acute computed tomographic (CT) evaluation of the patient with blunt abdominal trauma. DESIGN: Randomized controlled clinical trial. SETTING: Level I trauma center at a university-affiliated teaching hospital. PATIENTS: Five hundred adult patients sustaining blunt abdominal trauma and requiring urgent resuscitation and CT evaluation of the abdomen were eligible for the study. Those patients who were younger than 18 years, pregnant, or in police custody were excluded. One hundred six patients were excluded from the analysis (15 for inappropriate enrollment, 9 because a CT scan had not been performed, 1 owing to inability to accept a nasogastric tube, and 81 owing to missing or incomplete records). Three hundred ninety-four patients with an average age of 36 years, an average Revised Trauma Score of 10, and an average Glasgow Coma Scale score of 12 are included in the analysis. INTERVENTIONS: Patients were randomized via computer-generated assignment to 1 of 2 groups either receiving OC or not receiving OC (no OC) after placement of a nasogastric tube. All patients received intravenous contrast solution and then underwent helical CT scan of the abdomen and pelvis using the GE HiSpeed Advantage CT scanner (GE Medical Systems, Milwaukee, Wis). MAIN OUTCOME MEASURES: Abnormal CT results, need for laparotomy, missed gastrointestinal tract and solid organ injuries, nausea, and vomiting. RESULTS: There were 199 patients in the OC group and 195 patients in the no OC group. Vomiting occurred in 12.9% of patients and the incidence was not different between groups. One hundred five abnormal scans (50 OC and 55 no OC) were obtained and 33 patients with abnormal scans (19 OC and 14 no OC) underwent laparotomy. There was 1 nontherapeutic laparotomy in each group. There was 1 missed small-bowel injury in the OC group (sensitivity, 86%) and no missed small-bowel injuries in the no OC group (sensitivity, 100%). Six bowel injuries were identified at laparotomy in the OC group. Two of the injuries were perforations without contrast extravasation but with pneumoperitoneum in 1. Three bowel injuries were identified in the no OC group, none of which were perforations. Seven of the 9 patients with bowel injury at laparotomy had associated intra-abdominal injury. Specificity for solid organ injury was 94% in the OC group and 57.1% in the no OC group. Sensitivity for solid organ injury was 84.2% in the OC group and 88.9% in the no OC group. The average time to abdominal CT scanning after placement of a nasogastric tube was 39.02+/-18.73 minutes in the no OC group and 45.92+/-24.17 minutes in the OC group (P= .008). CONCLUSION: The addition of OC to the acute CT protocol for the evaluation of the patient with blunt abdominal trauma is unnecessary and delays time to CT scanning.

Abdominal Injuries↗
PubMed1998

Incidence and significance of free fluid on abdominal computed tomographic scan in blunt trauma.

OBJECTIVE: To determine the incidence and significance of free fluid on abdominal CT in blunt trauma. DESIGN: Retrospective chart review. METHODS: All blunt trauma patients with an abdominal computed tomographic scan from August of 1993 to December of 1995 were identified from the trauma registry at a Level 1 trauma center. A total of 1,159 computed tomographic scans were performed; records of 18 patients were excluded for incomplete records. Official reports of computed tomographic scans were reviewed for free fluid, solid organ injury, bladder injury, and pelvic fracture. RESULTS: Free fluid without solid organ injury was found in 3% (34 of 1141). Laparotomy was performed because of free fluid in 13 patients. There were six small bowel injuries and one diaphragm injury for a therapeutic laparotomy rate of 54%. Ten patients had trace free fluid and did not undergo laparotomy; none had a missed small bowel injury. CONCLUSIONS: The presence of more than trace amounts of free fluid without solid organ injury in patients with blunt trauma is a strong indication for exploratory laparotomy. Patients with isolated trace amounts of free fluid can be safely observed.

Abdominal Injuries↗
PubMed1998

Benchmarking the communication of continuous improvement activities.

Communication of a continuous improvement program in a large medical center was assessed using a formal benchmarking process with four non-health care organizations. Results indicated that continuous improvement must be integrated with the corporate strategic plan, must focus on customer satisfaction, and have active leadership support. A common framework should link different continuous improvement methodologies. Ongoing, open, multimedia two-way communication is required. Continuous improvement activities need to be integrated into all employees' daily work.

Benchmarking↗
PubMed1997

Examining technical aspects of the monoclonal antibody immobilisation of granulocyte antigen assay.

BACKGROUND AND OBJECTIVES: This study was an attempt to improve detection and characterization of alloantibodies to neutrophil antigens, using the monoclonal antibody immobilisation of granulocyte antigens (MAIGA) assay. MATERIALS AND METHODS: We explored the effect of different detergent concentrations, detergent class, stabilising additives, combinations of detergents, and use of a broad range of monoclonal antibodies on the results of the MAIGA assay. RESULTS: Non-ionic detergents, Triton X and Nonidet, were confirmed as the most suitable for solubilisation of the recognised, neutrophil-associated alloantigens. Anionic and zwitterionic detergents did not assist the demonstration and characterisation of new neutrophil alloantigens in the MAIGA assay. Some reproducible positive MAIGA assay results were obtained for antisera 01, 08, anti-RED, anti-NB2, and anti-NB1, using particular monoclonal antibodies. CONCLUSIONS: Although we are reluctant to suggest association of the targeted antigens with the particular glycoproteins identified by the capture monoclonal antibodies, NB1 glycoprotein may be closely associated, before or after antibody binding, with CD46, CD11b, CD50, and/or CD66b.

Antibodies, Monoclonal↗
PubMed1997

Detection of antibodies and delayed dermal hypersensitivity with different lots of Blastomyces dermatitidis yeast lysate antigen: stability and specificity evaluations.

Comparative evaluations were performed to assess the stability, sensitivity and specificity of eight lots of yeast lysate antigen prepared from a Blastomyces dermatitidis dog isolate (T-58). These antigens were prepared during the period from 1989 to 1995. The lysates were used in an ELISA for the detection of antibodies in serum specimens from dogs with blastomycosis and histoplasmosis. In order to evaluate the ability of the lysates to elicit delayed dermal hypersensitivity (DTH) responses, they were compared as skin-testing antigens in guinea pigs that were previously sensitized with B. dermatitidis or Histoplasma capsulatum killed whole yeast cells. All 8 of the lots of antigen detected antibody in the sera from dogs with blastomycosis (absorbance values ranged from 0.432 to 0.543; mean value of 0.508). The absorbance values ranged from 0.283 to 0.439 (mean value of 0.326) when the lysates were assayed against sera from dogs with histoplasmosis. All of the antigens were able to elicit a DTH response in B. dermatitidis immunized animals (mean axes of induration values ranged from 10.5 mm to 12.5 mm; mean value of 11.6 mm). In contrast, only minimal cross-reactivity was evidenced in the guinea pigs immunized with H. capsulatum (mean axes of induration values ranged from 0 to 4.5 mm; mean value of induration of 1.7 mm).

Animals↗
PubMed1996

Laparoscopic gastrostomy and jejunostomy are safe and effective for obtaining enteral access.

BACKGROUND: Laparoscopic gastrostomy (lap g-tube) and jejunostomy (lap j-tube) are relatively new procedures that do not require laparotomy. Our aim was to determine the role of laparoscopic feeding tube placement for enteral access and the safety of these techniques. METHODS: We reviewed our experience with attempted laparoscopic placement of 93 enteral tubes in 81 patients over a 3-year period. Patients received either a lap g-tube (n = 64), lap j-tube (n = 5), or both lap g/j-tube (n = 12). When enteral access was needed for nutritional support, the choice of lap g-tube or lap j-tube was based on risk of gastroesophageal reflux. RESULTS: The most common underlying conditions requiring tube placement were head and neck cancer (49%), neurologic disorders (19%), and trauma (11%). Mean operative times (minutes) were as follows (mean +/- SD): lap g-tube (39 +/- 7), lap j-tube (63 +/- 10), and lap g/j-tube (85 +/- 13). Lap g-tube placement was successful in 73 (96%) of 76 patients and lap j-tube in all 17 patients. The major complication rate for all tubes was 8% (7 of 93) and included gastrointestinal bleeding, wound infection, and failed placement. Five patients died in the 30-day period following surgery, but none of the deaths was procedure related. CONCLUSIONS: Laparoscopic tube placement should be considered for patients in whom endoscopy is not feasible or undesirable or who are undergoing other operative procedures. Lap g-tube and lap j-tube are safe procedures that avoid the potential risk of a laparotomy, and they can be done with a high success rate. This is a valuable approach for patients with head and neck cancer or neurologic disorders and for trauma patients with multiple disease processes.

Female↗
PubMed1996

A phase II trial of paclitaxel in the treatment of recurrent or metastatic soft tissue sarcomas or bone sarcomas.

The study aimed to determine the activity and toxicity of taxol in the treatment of recurrent or metastatic soft tissue sarcomas or osteosarcomas. The major findings are that five patients had stable disease after two cycles of chemotherapy but two of these patients were subsequently removed from the study at their own request. The other three patients progressed after an additional two cycles of chemotherapy. Seven patients progressed during the first two cycles and were removed from the study. One patient completed only one cycle of therapy and was deemed inevaluable for study response. There were eight episodes of grade 3 or 4 neutropenia and two episodes of grade 3 thrombocytopenia. One patient experienced grade 3 neurological toxicity and one patient grade 3 mucositis. Two patients are currently alive with progressing disease and one patient is alive with no evidence of disease after undergoing surgery and radiotherapy. The principal conclusions are that Paclitaxel is ineffective in treating recurrent or metastatic soft tissue sarcoma and osteosarcoma. Treatment at this dose is quite myelosuppressive, but toxicity is generally manageable. Further study of this agent is not justified in this setting.

Adult↗
PubMed1995

Glucagon, stress, and portal hypertension. Plasma glucagon levels and portal hypertension in relation to anesthesia and surgical stress.

Glucagon has been proposed as the mediator of splanchnic hyperemia in portal hypertension. Employing an assay specific for pancreatic glucagon, we reevaluated the relationship between this peptide and portal hypertension in the portal vein (PV)-stenosed rat model addressing, in particular, the effects of anesthesia and surgical stress. Plasma glucagon levels were similar in sham-operated and portal hypertensive rats: glucagon, sham vs PV stenosed: 110.7 +/- 17.1 pmol/liter vs 140.6 +/- 23.3 pmol/liter (NS). Furthermore, plasma levels of glucagon and the related peptide VIP were not significantly influenced by anesthesia or surgical stress, and levels remained similar under all conditions in sham-operated and PV-stenosed animals. We conclude that pancreatic glucagon is not elevated in the PV-stenosed rat; differences between these results and those describing hyperglucagonemia in this model cannot be explained on the basis of a differential response to stress but may reflect differences in glucagon assay system.

Anesthesia↗