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Biomedical subjects

E A Frost

Publications and source records attributed to E A Frost.

At least 19 recordsLinked to original sources
PubMed2000

Garlic extract (allium sativum) reduces migration of neutrophils through endothelial cell monolayers.

Leukocytes play an important role during inflammation. They migrate from intravascular spaces into tissues and attack micro-organisms. In a recent study, the inhibitory effects of the non-steroidal anti-inflammatory drug, ibuprofen, on leukocyte transmigration were demonstrated using an in vitro assay. Little is know about the cellular effects of garlic extracts (allium sativum). The aim of the current study was to investigate the influence of garlic extract on leukocyte migration through endothelial cell monolayers and thereby evaluate a possible role in inflammatory processes. Human umbilical endothelial cells were cultured on microporous membranes to make an endothelial cell monolayer (ECM). Freshly isolated neutrophils were used in a recently described migration assay. The amount of untreated neutrophils migrating through the untreated ECM was used as control and set at 100%. Neutrophils and/or ECM were pre-treated with garlic extract using moderate, as well as higher and lower concentrations. Moderate plasma concentrations garlic extract inhibited neutrophil migration through ECM significantly (64 +/- 5.8% SD; P < 0.05), when both cell types were treated, (a situation that may have clinical relevance). Treating either neutrophils or ECM alone showed significant reductions in migratory rate (neutrophils treated alone: 81 +/- 7.7% SD, p < 0.05; ECM alone: 70 +/- 6.7%, p < 0.05). Thus, garlic extract is identified as a potent inhibitor of leukocyte migration through endothelial cell monolayers. Treatment of both cell types has an additive effect. Endothelial cells seem to be more affected than neutrophils. Further investigations are necessary to understand the potential clinical consequences. During inflammation, neutrophils play an important role. They migrate rapidly from the vascular space into tissues to destroy invading micro-organisms. During migration through endothelial cell monolayers (ECM), neutrophils undergo morphologic changes from rounded, relatively smooth cells to elongated, ruffled cells with pseudopodia. Recently, the influence of the non-steroidal anti-inflammatory drug, ibuprofen, on leukocyte function was investigated using an in vitro double chamber migration assay that includes ECM. Garlic extract (allium sativum) is a widely used "over the counter" herbal preparation. The effect of garlic on lipid metabolism is well documented. Previous studies have examined the influence of the extract on leukocyte function, e.g. respiratory burst. The effect of garlic on thrombocyte aggregation has also been recently described as has an anti-fungal effect. To our knowledge, nothing is known about the effect of garlic leukocyte transmigration. Therefore, we aimed to examine the effects of garlic extract on leukocyte transmigration through ECM in an in-vitro cell co-culture system.

Allium↗
PubMed1999

Assessment of right ventricular function by right ventricular systolic time intervals in acute respiratory failure.

OBJECTIVE: Whether right ventricular systolic time intervals accurately reflect right ventricular function in patients with acute respiratory failure was determined by assessing the correlation between right ventricular systolic time intervals and the right ventricular end-systolic pressure-volume relationship. DESIGN: A prospective study. SETTING: A surgical intensive care unit in a university hospital. PATIENTS: Twenty patients with acute respiratory failure. MEASUREMENTS AND MAIN RESULTS: Right ventricular systolic time intervals were determined by the simultaneous graphic display of the electrocardiogram, the phonocardiogram, and the pulmonary artery pressure curve and were expressed as a ratio of the pre-ejection period/right ventricular ejection time. The total electromechanical systole was measured from the onset of the electrocardiographic wave complex to the pulmonic component of the second heart sound. Right ventricular ejection time was measured from the rapid upstroke of the pulmonary artery pressure curve to the dicrotic notch. Right ventricular ejection fraction, from which right ventricular end-systolic volume was derived, was measured by the thermodilution technique. Pulmonary artery dicrotic notch pressure was used as an estimate of right ventricular end-systolic pressure. Data were collected at the baseline and after one or two alterations in preload, to define the right ventricular end-systolic pressure-volume relationship line. There was an inverse correlation between the pre-ejection period/right ventricular ejection time ratio and the slope of the right ventricular end-systolic pressure-volume relationship line (r2 = .67; p < .0001). When patients were divided into two groups, based on the pre-ejection period/right ventricular ejection time ratio, the slope of the right ventricular end-systolic pressure-volume relationship line was lower in the group with a high pre-ejection period/right ventricular ejection time ratio (p < .0001). No difference in other hemodynamic data, between the two groups, was noted. CONCLUSIONS: These data suggest that right ventricular systolic time intervals reflect right ventricular performance accurately in patients with acute respiratory failure.

Acute Disease↗
PubMed1994

Anaesthesia for the patient with acquired immune deficiency syndrome--a review.

Acquired immunodeficiency syndrome affects over 10 million persons worldwide. The disease represents an enormous cost to society in health care resources and in loss from the workforce. Although initially reported in 1980 as a disease affecting mainly homosexuals and intravenous drug abusers with a predominance in males, the male to female ratio was close to parity by 1992. The disease attacks all systems in the body. Preanaesthetic evaluation focuses on assessment of lung function and presence of infection, evaluation of endocarditis and treatment of congestive failure, rehydration and correction of electrolyte imbalances, transfusion and documentation of central nervous system manifestations. The Center for Disease Control and Prevention has produced guidelines to protect health care workers from transmission of the virus. Although the risk of infection is extremely low, these precautions should be routinely adopted.

Acquired Immunodeficiency Syndrome↗
PubMed1994

Perioperative management of the head trauma patient.

Realizing that miracle drugs that can reverse severe brain damage have not yet been identified, studies in recent years have focused on identifying risk factors for head trauma and resuscitative events that might impede or improve outcome. Risk factors for poor outcome include advanced age, alcoholism, delay in transfer and operation, management errors and technical mistakes. Quality assurance programmes, now established in all United States hospitals, may be flawed in that assessments of preventable trauma deaths are often based on unsubstantiated subjective case review methods. Studies of the cerebral effects of anaesthetic agents have reconfirmed the detrimental effects of nitrous oxide in the trauma victim. Ketamine, a N-methyl D-aspartate receptor antagonist, has shown surprising cerebral protective effects in animal models. Appropriate fluid therapy after head injury requires avoidance of sugar-containing solutions, maintenance of normovolaemia and consideration of use of hypertonic solutions to maintain vascular volume. Although hypothermia continues to be an appealing means of affording brain protection after head injury, the degree and duration have still not been established. Establishment of the airway in the neck injured patient should be by careful endotracheal tube placement which causes less cervical movement than mask ventilation and less risk of infection or trauma than the nasotracheal route.

Anesthetics↗
PubMed1991

Extracorporeal shock wave lithotripsy of gall stones: an in vitro comparison between an electrohydraulic and a piezoceramic device.

A comparative study of the effectiveness of two types of lithotripter in fragmenting gall bladder stones is reported. The machines used were a Piezolith 2300, which generates shock waves by the piezoceramic principle, and a Dornier MPL 9000, which produces the shock waves by underwater spark discharge. With each machine, corresponding stones of 45 pairs of weight and volume matched calculi (median volume 0.5 cm3, median diameter 10.5 mm) obtained at cholecystectomy were treated. All stones were successfully disintegrated (fragments smaller than 2 mm) with up to 5400 (median 628) shocks with the Piezolith and 3450 (median 428) shocks with the MPL 9000 lithotripters. With the Piezolith, operating at the highest power setting, a 1.65 fold median higher number of shocks was required for stone fragmentation than with the MPL 9000 at a medium power setting. Stone volume seemed to be the only determinant which affected ease of fragmentation; composition and density of the stones as assessed by computed tomography did not seem to be governing factors.

Cholelithiasis↗
PubMed1989

The lessons from in vitro lithotripsy for the clinical treatment of gallstones.

Fifty-eight gallbladder stones were treated in vitro, using a Wolf Piezolith 2300 lithotripter, to discover whether complete fragmentation (i.e., no particles greater than 2 mm diameter) could be achieved by lithotripsy alone. In 16 stones this was accomplished with up to 6000 shocks being administered. The degree of fragmentation was judged first by eye during the experiment and then by both microscopy and sieving of the debris. Eye judgement proved to be an unreliable indicator with 23 of the 42 stones in the failed lithotripsy group receiving 6000 shocks or less. Cholesterol analysis and high resolution radiography revealed no significant differences between the successfully and unsuccessfully fragmented stones, but X-ray diffractometry did show a higher incidence of inorganic calcium salts in the latter group. This study shows that lithotripsy can successfully fragment gallbladder stones, but that a minimum of 6000 shocks, using the Piezolith 2300, should be given to ensure adequate treatment. Additionally, the presence of radiopaque stones does not necessarily preclude successful treatment by this method.

Cholecystectomy↗