An investigation into the role of coagulation factor XIII in ADP- induced aggregation and fibrinogen binding with rabbit platelets

Because there was a possibility that activated factor XIII (factor XIIIa) might stabilize a platelet-fibrinogen aggregate through its crosslinking action, we have isolated plasma factor XIII, activated it, and studied the effect of factor XIIIa at a concentration of 3.3 micrograms/ml on aggregation and 125I-fibrinogen binding of rabbit platelets stimulated with 9 microM ADP. Factor XIIIa did not cause aggregation in the absence of ADP, nor did it enhance ADP-induced aggregation or substantially stabilize the platelet aggregate. The presence of factor XIIIa did not affect the amount of fibrinogen bound to platelets immediately after stimulation with ADP, but it appeared to cause a slow specific binding of 125I-fibrinogen to platelets whether or not they were stimulated with ADP. This binding, which was not inhibited by prostaglandin E1, did not lead to aggregation and was accompanied by crosslinking of fibrinogen through its A alpha and gamma chains, either to other fibrinogen molecules or to a platelet protein or proteins.     

Circadian and sleep disturbances in the elderly

The incidence of disturbed sleep is strongly increased in healthy and demented elderly. Age-related alterations in the circadian timing system appear to contribute strongly to these problems. With increasing age, a lack of input to the suprachiasmatic nucleus (SCN), the biological clock of the brain, may accelerate de-activation of neurons involved in the generation of 24-h rhythm or output of this rhythm. This process appears to be reversible, since supplementation of stimuli that impinge on the SCN can re-activate these neurons and ameliorate disturbances in the sleep–wake rhythm.     

Topical corticosteroids in psoriasis: strategies for improving safety

Corticosteroids are a mainstay of topical therapy for psoriasis. While efficacious and relatively safe when used carefully, the potential for side effects, notably skin atrophy and adrenal suppression, have been associated with excesses in potency, prolonged or widespread use. The International Psoriasis Council Working Group on Topical Therapy has reviewed the efficacy and safety of topical corticosteroids and recommends strategies for safe, long‐term use of these agents.     

Long-term studies after intra-arterial cytostatic therapy of head and neck tumors

This study on selected tumour patients demonstrates relationship between the effectiveness of preoperative, postoperative and palliative intra-arterial cytostatic treatment of tumours of the head and neck and the long-term survival. During the period ranging between 3.5 and 9 years after preoperative treatment of 11 cases, palliative treatment of 6 cases, resulting in 100% tumour regression, and postoperative-adjuvant treatment of 23 cases (selected from 254 cases receiving intra-arterial treatment), local recurrence was observed in 10 cases. The question is raised of the necessity of radical surgery corresponding to the original tumour after preoperative treatment resulting in a completely tumour-free state.     

Atrial fibrillation with neonatal pulmonary lymphangiectasia

A female infant born at 28 weeks' gestation was found to have mild hydrops foetalis. Initial echocardiography showed a structurally normal heart. During the first week of life, episodic atrial tachycardia with 1:1 or 2:1 conduction was seen, requiring therapy with digoxin. The infant remained ventilator dependent, with a persistent, chylous pleural effusion which contained a preponderance of lymphocytes. Congenital pulmonary lymphangiectasia (CPL) was confirmed histologically. Worsening episodes of atrial tachycardia, including episodes of atrial fibrillation, were further investigated and a repeat echocardiogram revealed thickening of the entire right atrial wall. The cardiac findings of a thickened right atrial wall with the histological signs of myocarditis were thought to be the cause of paroxysms of atrial fibrillation, an extremely rare arrhythmia in the neonatal period. To the authors' knowledge there have been no previous reports of CPL in association with the cardiac abnormalities described herein.     

Abdominal tuberculosis: CT evaluation

The computed tomography (CT) scans of 27 patients with abdominal tuberculosis were reviewed retrospectively to determine the range of abdominal involvement. Most patients had been at increased risk because of intravenous drug abuse, alcoholism, acquired immunodeficiency syndrome (AIDS), cirrhosis, or steroid therapy. The etiologic agent was Mycobacterium tuberculosis in 23 patients and M. avium-intracellulare in four patients with AIDS. In five patients, tuberculosis was limited to the abdomen. CT findings included adenopathy, splenomegaly, hepatomegaly, ascites, bowel involvement, pleural effusion, intrasplenic masses, and intrahepatic masses. Characteristic features were a tendency for adenopathy to prominently involve peripancreatic and mesenteric compartments, low-density centers within enlarged nodes, complex nature of the ascites, and adenopathy adjacent to sites of gastrointestinal tract involvement. Recognition of these manifestations and maintenance of an index of suspicion, especially in patients at risk, should help optimize the correct diagnosis and management of intraabdominal tuberculosis.     

Monomeric and polymeric collagen-induced platelet aggregation in citrated and heparinized platelet-rich plasma

The physical and chemical properties of Type I bovine collagens were studied in relation to their platelet aggregating activity in citrated and heparinized human platelet-rich plasmas (PRP). Despite close similarities in physical and chemical properties, significant differences were found in platelet aggregating potency between two monomeric atelocollagens. Skin atelocollagen was a potent and corneal atelocollagen was a very weak inducer of platelet aggregation in citrated and heparinized PRP. In a polymeric form, however, corneal atelocollagen was a stronger platelet aggregating agent than monomeric skin acid-soluble or atelocollagen. Removal of the telopeptides altered some of the characteristics of the platelet aggregation induced by monomeric skin collagen. The rate and maximum extent of aggregation were the same with skin acid-soluble (intact) and atelocollagens in either type of PRP, but the lag periods and aggregation times were longer in citrated and somewhat shorter in heparinized PRP with skin atelocollagen than with acid-soluble collagens. The possible mechanisms leading to the differences observed in platelet aggregating activity of collagens in different physical states and from different tissues, and their distinct platelet aggregation patterns in differently anticoagulated PRP, are discussed.     

Ascorbate-2-phosphate in red cell preservation. Clinical trials and active components

A red cell additive solution (AS-005) containing ascorbate-2-phosphate (AsP) to maintain 2,3-diphosphoglycerate, plus adenine, phosphate, and mannitol to retain viability and reduce hemolysis, was evaluated by human clinical trials. A crossover design was used with another additive solution (Nutricel AS-3, Cutter Laboratories) serving as the control for each donor. Each additive solution was evaluated at 35 and 42 days of storage. There was no significant difference between the red cell viability of the two storage solutions at either time period. Split-bag, AS-005 in vitro studies at two temperatures (2.5 and 5.5 degrees C), both within the range of 1 to 6 degrees C approved by the American Association of Blood Banks and the Food and Drug Administration, resulted in dramatically different in vitro parameters, including a threefold difference in 2,3-diphosphoglycerate (2,3-DPG), a fivefold difference in glucose, and significant differences in pH and adenosine triphosphate. High-pressure liquid chromatography data confirmed the preliminary report that 1 to 2 percent (wt/wt) oxalate was present in preparations of AsP. In vitro storage data confirmed that oxalate is the active component of AsP that preserves 2,3-DPG during storage.