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Biomedical subjects

J A Hopkins

Publications and source records attributed to J A Hopkins.

At least 37 records · Page 2Linked to original sources
PubMed1991

Adjunctive antimicrobials in surgery of soft tissue infections: evaluation of cephalosporins and carbapenems.

The authors report three trials of B-lactams and carbapenems for soft tissue infections treated on a surgical service: 1) cefmetazole versus cefoperazone, n = 44; 2) cefotetan versus cefoxitin, n = 24; and 3) meropenem versus imipenem, n = 44. A total of 138 hospitalized patients were enrolled with 112 meeting evaluability criteria. Four hundred twenty-three isolates were cultured (mean, three/patient) of which 67 per cent were aerobes and 33 per cent anaerobes. Cure rates for each trial were: 1) 93 per cent; 2) 92 per cent; 3) 100 per cent. Failures were caused by resistant organisms (Streptococcus group D, Bacteroides fragilis and Pseudomonas) appearing in incompletely drained infection sites. Three patients receiving meropenem had adverse effects (headache, nausea) and one receiving cefoxitin (truncal rash). Operative drainage and debridement remain the critical elements in therapy. Agents with longer half lives allowing twice daily dosing (cefmetazole and cefotetan) were as effective and less expensive than multiple doses of short-acting agents. The extended spectrum carbapenems are most useful for severe infections or resistant organisms.

Adult↗
PubMed1987

Pathogenesis of Campylobacter fetus infections: serum resistance associated with high-molecular-weight surface proteins.

Campylobacter fetus subspecies fetus causes both systemic and diarrheal illnesses. We studied 38 strains of C. fetus isolated from 34 patients; underlying illness was present in eight (89%) of nine patients with only systemic isolates compared with three (20%) of 15 patients with only fecal isolates (P = .002). In a standardized assay of susceptibility to normal human serum, 27 (71%) strains were resistant, six (16%) had intermediate susceptibility, and five (13%) were serum sensitive. Major protein bands migrating at 100 kDa or 125 kDa on polyacrylamide gels were present in all of the 25 serum-resistant strains tested but in only four of seven serum-sensitive isolates of C. fetus from humans and animals (P = .007). The presence of these bands was associated with type A lipopolysaccharide. A low-passaged strain, 82-40, was serum resistant and contained the 100-kDa protein; however, a spontaneous mutant of this strain lacked this band and was serum sensitive. The 100-kDa and 125-kDa proteins of three strains of C. fetus were antigenically cross reactive or identical and were exposed on the surface of the C. fetus cell. Serum resistance is inherent to most C. fetus isolates from humans and is associated with the presence of cross-reactive surface proteins.

Animals↗
PubMed1987

A comparison of cefotaxime versus cefamandole in prophylaxis for surgical treatment of the biliary tract.

Fiscal considerations prompted comparison of cefotaxime (a third generation cephalosporin) with cefamandole (a second generation cephalosporin) for prophylaxis in the surgical treatment of the biliary tract. One hundred and eight patients who underwent an operation upon the biliary tract received three 1 gram doses of cefotaxime (54 patients) or cefamandole (54 patients) at induction of anesthesia and then one and three hours later. The study was prospective, blinded and randomized. The groups (cefotaxime versus cefamandole) were statistically comparable for age, sex, diagnosis, type and duration of operation and positive cultures. The most prevalent bacteria isolated from qualitative aerobic and anaerobic cultures of bile and the wall of the gallbladder were Escherichia coli, Streptococcus and Klebsiella. The incidence of bactibilia in patients with one of these conditions was: 75 per cent for cancer; 69 per cent for patients more than 60 years old; 33 per cent for jaundice; 58 per cent for pancreatitis; 60 per cent for exploration of the common bile duct, and 22 per cent for acute cholecystitis. Microbiologic agar diffusion assays of tissue from the wall of the gallbladder, subcutaneous fat and rectus muscle and samples of bile and serum obtained 30 minutes after the second dose of antibiotic showed a statistically significant greater concentration of cefamandole in the wall of the gallbladder. Otherwise there was no difference between the concentration of cefamandole and cefotaxime. The groups showed no statistical difference for temperature of more than or equal to 38 degrees C. on two consecutive measurements, postoperative wound and urinary infections, postoperative hospital stay and days in the intensive care unit and incidence of readmission within a month. Prophylactic use of cefotaxime in a three dose regimen provided no advantage in prophylaxis compared with cefamandole.

Adult↗
PubMed1986

Lipopolysaccharide structures in Enterobacteriaceae, Pseudomonas aeruginosa, and Vibrio cholerae are immunologically related to Campylobacter spp.

To determine whether lipopolysaccharide (LPS) structures of Campylobacter species are immunologically related to those of 11 other gram-negative organisms, we immunoblotted from polyacrylamide gels the LPS of these strains with immune rabbit serum raised against six Campylobacter jejuni strains and two Campylobacter fetus strains. The LPS studied were from Salmonella minnesota wild type and Ra to Re mutants, Salmonella typhi, Escherichia coli, Yersinia enterocolitica, Vibrio cholerae, and Pseudomonas aeruginosa. None of the 11 LPS preparations was recognized by the eight antisera, but antisera to each of the Campylobacter strains recognized core determinants of some LPS preparations. Antiserum directed against the most serum-sensitive C. jejuni strain, 79-193, was the only antiserum sample that recognized core regions of the rough Salmonella mutants. In converse experiments, when LPS preparations from five Campylobacter strains were blotted with antiserum to Salmonella lipid A, recognition of core structures of each was shown; data from an enzyme-linked immunosorbent assay confirmed this result. In contrast, antiserum to Salmonella typhimurium Re LPS showed no reactivity. We conclude that LPS of Campylobacter strains share lipid A antigenic determinants with the core region of LPS of several other gram-negative organisms.

Campylobacter↗
PubMed1986

Antigenicity of Campylobacter jejuni flagella.

We studied the antigenicity of a wild-type flagellate and motile (F+M+) Campylobacter jejuni strain (81116) and two daughter mutants, one flagellate and immotile (F+M-) and one aflagellate and immotile (F-M-). By sodium dodecyl sulfate-polyacrylamide gel electrophoresis of acid-extracted surface proteins, a 63-kilodalton (kDa) band identified from sheared flagella as the flagellar protein was present in the F+M+ and F+M- strains but not in the F-M- strain. No other differences in protein profile among the three strains were noted. By Western blotting, serum from rabbits immunized with either the F+M+ or F-M- strain detected a 63-kDa protein in the F+M+ and F+M- strains but not in the F-M- strain. That the F-M- antiserum recognized the 63-kDa band suggests that small amounts of this protein or a cross-reacting antigen is present on the F-M- strain. By counterimmunoelectrophoresis of the acid-extracted preparations with immune sera, all three strains were found to share three major antigens, but a fourth antigen with a net positive charge was present only in the F+M+ and F+M- strains. Antisera to five C. jejuni and two Campylobacter fetus strains recognized the 63-kDa protein of purified F+M+ flagella in Western blots, demonstrating a common antigen is present, but enzyme-linked immunosorbent assay results suggest that the sharing of this antigen among Campylobacter strains is variable.

Antigens, Bacterial↗
PubMed1985

Antigenic heterogeneity of lipopolysaccharides from Campylobacter jejuni and Campylobacter fetus.

The lipopolysaccharide (LPS) structure of Campylobacter spp. can be visualized with polyacrylamide gel electrophoresis by examining proteinase K-treated whole cell lysates. Polyacrylamide gel electrophoresis LPS profiles of C. jejuni strains are rough type with low concentrations of low-molecular-weight polysaccharide side chains, serum-resistant C. fetus strains have smooth-type LPS, and serum-sensitive C. fetus strains have rough-type LPS. We electroblotted the proteinase K-treated whole cell lysates of 17 C. jejuni and 9 C. fetus strains from polyacrylamide gel electrophoresis to nitrocellulose paper to examine antigenicity to immune rabbit sera. There was virtually no antigenic cross-reactivity of C. jejuni and C. fetus LPS. Among C. jejuni strains, core LPS structures were cross-reactive, but the O-polysaccharide side chains were best recognized by homologous antisera. Antisera to several serum-resistant C. fetus strains recognized only the polysaccharide side-chain regions of serum-resistant strains and no part of the LPS from the sensitive strain. Antiserum raised against a serum-sensitive C. fetus strain but not homologous antisera recognized the core region of the LPS of the serum-resistant C. fetus strains. These findings suggest that core LPS antigens are widely shared within C. fetus subsp. fetus strains but that in the serum-resistant strains this core region is not surface exposed and therefore not immunogenic to rabbits infected with whole cells.

Blood Bactericidal Activity↗
PubMed1984

Campylobacter jejuni outer membrane proteins are antigenic for humans.

All Campylobacter jejuni strains have a major outer membrane protein (OMP) that migrates between a molecular weight of 41,000 (41K) and 45K and represents more than 50% of protein present, plus several more minor bands. Using 125I-radiolabeled C. jejuni cells in a radioimmunoprecipitation procedure to assess whether the OMPs were antigenic, we studied serum from rabbits immunized with C. jejuni cells, from humans convalescent after C. jejuni infection, and from appropriate controls. In this assay, the major OMP was the major antigen for both homologously and heterologously immunized rabbits and infected humans but not for controls. Minor bands at 29K and 50K were also antigenic. We tested human and animal sera in a Western blot procedure using anti-immunoglobulin A (IgA), anti-IgG, or anti-IgM conjugates. Homologous and heterologous immune rabbit serum, but not control serum, recognized a large number of membrane proteins between 15K and 91K, including the major OMP. Both Campylobacter spp.-infected and healthy humans showed IgA, IgG, and IgM responses to the major OMP, although the response was more pronounced in the former group. Sera from infected humans recognized several minor bands to a significantly greater extent than control sera did. Our data suggest that there is antigenic similarity between the OMPs of different C. jejuni strains and that some of these OMPs recognized by infected animals and humans have vaccinogenic potential.

Adult↗
PubMed1983

Clinical trial of an emergency resuscitation algorithm.

Clinical trials of a resuscitation algorithm for patients entering the Surgical Emergency Department (ED) with acute hypotension were conducted for a 30-month period. The intent was not to compare good management with bad, but rather university-run county hospital services with and without an algorithm. The study group was comprised of 603 hypotensive patients out of 6833 consecutive admissions. The effects of the policy of using a resuscitation algorithm were evaluated by the outcomes of the patients who were treated by residents given the algorithm (protocol group) versus those treated by residents not given the algorithm (control group). The efficacy of the algorithm, per se, was evaluated by outcomes of patients whose management was in satisfactory compliance with the algorithm as compared with those whose management deviated from the algorithm. The patients were also evaluated by the primary cause of their hypotension and the presence of severe associated illnesses. Outcomes of patients treated by residents given the algorithm were as good and in a number of respects better than those of patients treated by residents without the algorithm. The mean resuscitation time of the protocol group was markedly and significantly less than that of the control group indicating that the policy of using the algorithm facilitated resuscitation even though it was not always properly followed. Patients with trauma, hemorrhage, and sepsis, whose care was in satisfactory compliance with the algorithm had shorter resuscitation times, lower MAP-time deficits, and less shock-related complications. The algorithm which is primarily directed toward fluid resuscitation did not appear to be efficacious for patients whose trauma was primarily head injury, where fluid restriction may be the therapy of choice.

Adolescent↗
PubMed1983

Clinical aspects of resuscitation with and without an algorithm: relative importance of various decisions.

Clinical description was made of a series of hypotensive patients resuscitated with and without an algorithm. Of 603 hypotensive patients, there were 114 (19%) deaths and 169 (28%) patients with complications; the average low MAP was 53 +/- 25 mm Hg. Of 169 patients with complications, 48 (28%) had shock-related (SR) complications; 25 (52%) of these patients died. There were 265 (44%) patients who had severe associated diseases and these patients comprised the group most vulnerable to complications and death; in this group, there were 41 patients with SR-complications who had significantly higher mortality, longer resuscitation times, lower MAP, more deviations from the algorithm, and more delays in resuscitation than did those with nonshock-related complications. Multiple deviations from the algorithm were associated with longer resuscitation times, and higher incidence of SR complications. Most of the delays in resuscitation of these patients and most of the SR complications could have been prevented. Seventeen percent of hypotensive patients entering the emergency department (ED) normally carried low arterial pressures, which averaged 75 +/- 3 (SD) mm Hg; this was more common, but not confined to young females. Of the 603 patients who actually were hypotensive, 6% were admitted in arrest (phase I), 18% in severe shock (phase II, MAP less than 60 mm Hg), 52% in moderate shock (phase III, MAP less than 80 mm Hg), and 24% were normotensive but subsequently became hypotensive (phase IV). The importance of various decision nodes of the algorithm were evaluated. The present algorithm, designed for these hypotensive emergency patients, provides a framework for fluid management that expedites resuscitation and reduces complications related to shock. We conclude that: (a) delays in resuscitation can be clearly related to an increased incidence of SR complications; (b) when the algorithm was satisfactorily followed, there was faster resuscitation and less SR complications; and (c) when the algorithm was satisfactorily followed in patients with severe associated illnesses, there was also shorter ICU stay, shorter hospitalization and decreased mortality.

Adolescent↗
PubMed1983

Identification and characterization of Campylobacter jejuni outer membrane proteins.

Outer membrane proteins from isolates of Campylobacter jejuni were examined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Sarcosinate-insoluble membrane preparations were outer membrane enriched based on increased ketodeoxyoctonate concentrations, the presence of surface-exposed 125I-labeled proteins that were hydrophobic, and similarity to membrane vesicle (bleb) sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles. Most isolates contained a single major band with molecular weight of 41,000 to 45,000. Profiles of C. jejuni and Campylobacter coli isolates were indistinguishable, but either could be easily differentiated from Campylobacter fetus and Campylobacter faecalis. The profiles were stable for strains under a variety of growth, incubation and passage conditions. We classified 110 isolates from patients with sporadic campylobacter enteritis into nine subtypes based on differences in outer membrane sodium dodecyl sulfate-polyacrylamide gel electrophoresis profiles. Two categories accounted for 76% of the isolates. Complete concordance was observed in subtypes of strains obtained from epidemiologically related cases. Thus, comparison of the major outer membrane proteins of C. jejuni is a useful technique for investigating the transmission of this organism and may provide a basis for immunological characterization of the outer membrane proteins.

Bacterial Outer Membrane Proteins↗
PubMed1982

Clinical trial of an algorithm for outcome prediction in acute circulatory failure.

The authors evaluated prospectively an index for outcome prediction previously developed retrospectively from the cardiorespiratory data of a series of 113 critically ill postoperative general surgical patients. A predictive score generated by nonparametric multivariate analysis of the observed value for each cardiorespiratory variable and the frequency distributions of survivors' and nonsurvivors' values of that variable at each stage of postoperative shock. An overall global predictive index was then generated from the sum of the weighted predictive scores in each variable. This predictive index was tested prospectively in a new series of 156 operations and was found to be 94% accurate for the values of the last available data set, suggesting that the method satisfactorily predicts outcome. This index may be used as an objective measure of the severity of illness; i.e., it may be used to track the clinical course of postoperative general surgical patients during periods of critical illness. It was concluded that the predictive index aids in evaluation of monitored cardiorespiratory variables, improves interpretation of physiologic alternation, and facilitates clinical decision-making of critically ill patients at the bedside.

Adult↗
PubMed1981

Comparison of the relative effectiveness of colloids and crystalloids in emergency resuscitation.

Over a 2.5 year period, the fluid management of 600 hypotensive patients entering our surgical emergency department was evaluated during a prospective clinical trial of a resuscitation algorithm. The major clinical determinants (low mean arterial pressure, age, severity of illness, primary illness or injury, amount of blood loss, volume of fluids given, use of a protocol or clinical algorithm and satisfactory compliance with the algorithm) were controlled by grouping the patients into specific strata; the resuscitation times were almost always shorter with a regimen of about one-fourth colloids than with crystalloids only. This is consistent with the observations of greater increases in hemodynamic and oxygen transport variables after albumin than after lactated Ringer's solution when the latter was given in either 2 or 4 times the volume.

Adult↗
PubMed1980

Treatment of surgical emergencies with and without an algorithm.

A patient care algorithm was developed for resuscitation of patients entering the surgical emergency department with hypotension. The diagnostic workup, monitoring, and therapy were progressively excalated according to admission blood pressure and responses to therapeutic interventions. The branching-chain logic is ideally suited for rapid decision making in emergency conditions where the need is most urgent, the time constraints are most severe, and the potential improvements in terms of patient salvage are greatest. Preliminary results from these ongoing clinical trials indicate that (1) physicians can and will use an algorithm for emergency medical service resuscitation; (2) in a university hospital with a large emergency service and a commitment to emergency care, the physicians using the aigorithm performed as well as and in some instances better than those not using the algorithm; and (3) the use of the algorithm may prevent delays in resuscitation and lead to less morbidity and mortality. Thus, we conclude that the algorithm helps to organize emergency care, establish standards, and improve care.

Adult↗
PubMed1980

Pathogenesis of respiratory failure (ARDS) after hemorrhage and trauma: I. Cardiorespiratory patterns preceding the development of ARDS.

To evaluate clinical and physiologic determinants of adult respiratory distress syndrome (ARDS), we studied 152 consecutively monitored patients with trauma and hemorrhage: 60 developed ARDS. The cardiorespiratory patterns of hemorrhage and trauma patients who did not develop ARDS were compared to those who subsequently did develop ARDS, but before the time of their ARDS. Comparisons also were made in the patients with trauma and those with hemorrhage, as well as in those who survived and those who did not. Hemorrhage and trauma patients who developed ARDS had greater reductions in blood volume, red cell mass, PaCO2 and O2 delivery throughout all stages, as well as greater pulmonary vascular resistance index (PVRI) and pH in the early and middle stages. Nonsurvivors of ARDS had greater deficits in blood volume and red cell mass, higher PVRI and pH, as well as lower central venous pressure (CVP), hemoglobin (Hgb), and PaCO2 than did ARDS survivors. Hemorrhage patients had lower blood volume, left ventricular function, O2 delivery and VO2, as well as higher systemic vascular resistance index (SVRI), PVRI, and O2 extraction than either the trauma patients or normal subjects. Description of the temporal cardiorespiratory patterns before the clinical appearance of ARDS showed the progressive appearance of these deficits beginning 36 h before the hypoxemia was observed. The data are consistent with the concept that ARDS after hemorrhage and trauma is preceded by hypovolemia, reduced myocardial performance, inadequate O2 delivery, and inadequate O2 extraction needed to maintain VO2 at the elevated levels demanded by the increased metabolic requirements of the injured patients. Thus, the so-called shock lung is a complication of shock associated with hypovolemia, hypoxemia, and inadequate cardiac compensatory responses to increasesd O2 demands.

Female↗
PubMed1979

Behavior of vaccine revertants of temperature-sensitive mutants of influenza virus in ferret tracheal organ culture.

A live attenuated influenza vaccine candidate was not genetically stable when administered to some children who lacked antibody to surface proteins of the virus. To obtain additional biological information about these revertants, the vaccine strain, the wild-type parental strain, and isolates recovered from inoculated children during a vaccine trial were evaluated in ferret tracheal organ culture for effects on the ciliated epithelium and replication at both permissive and restrictive temperatures. The studies revealed that the vaccine strain destroyed cilia and replicated to high titer at its permissive temperature (33 degrees ) but caused minimal damage and replicated to very low titer at its restrictive temperature (37 degrees C). The wild-type parent destroyed cilia at both 33 and 37 degrees C. Isolates which were no longer temperature sensitive (ts(+)) destroyed cilia at both restrictive and permissive temperatures and grew to high titer. Isolates which retained the ts phenotype behaved as the vaccine strain in this system. The ts(+) virus recovered from volunteers behaved like the wild-type parent, which suggests that these viruses had not merely lost their ts phenotype, but had undergone reversion to wild type. Important information about the genetic stability of temperature-sensitive influenza vaccine strains recovered from volunteers can be obtained by evaluating them in ferret tracheal organ culture.

Animals↗
PubMed1978

Resuscitation algorithm for management of acute emergencies.

Assuming that unrecognized or inadequately corrected hypovolemia results in higher mortality and morbidity rates, we developed a systematic approach to resuscitation that would: 1) identify criteria to aid in the recognition of hypovolemia and ensure the expeditious correction of this defect without interfering with diagnostic workup and management; 2) define criteria to prevent fluid overload which may jeopardize the patient's course, and 3) express these criteria in an explicit, systematic, patient care algorithm, ie, protocol, useful to both the resident and the practicing physician. We are now conducting prospective clinical trials with one service using the algorithm and the others acting as the control group. Preliminary results comparing patient outcomes suggest that the algorithm improves patient care by shortening resuscitation time and results in fewer hospital days, intensive care unit days, febrile days, and days on mechanical ventilation as well as reduced mortality. The algorithm provides a systematic plan to organize patient care so that the most urgently needed procedures are not delayed or overlooked.

Algorithms↗