Platelet membrane microparticles in blood bank fresh frozen plasma and cryoprecipitate

Cryoprecipitate has been demonstrated to correct the bleeding abnormality of patients with some congenital (storage pool disease) and acquired (uremia) platelet abnormalities, but the reason for this effect is unknown. We found significant platelet contamination in plasma harvested to prepare fresh frozen plasma and cryoprecipitate. The platelet membrane microparticles produced by freezing and thawing of the plasma were highly concentrated in cryoprecipitate and may contribute to its therapeutic effect.     

Imaging of cardiac transplantation rejection in primates using two new antimyosin agents.

Indium-111-labeled monoclonal antimyosin Fab has been used to image myocardial infarction, myocarditis and cardiac transplant rejection with localization in myocytes that have suffered irreversible loss of cell membrane integrity. Technical factors potentially limiting clinical usefulness of 111In antimyosin include dosimetry (72 hr half-life of 111In), slow blood clearance of antibody proteins delaying optimal imaging to 24 to 48 hr postinjection and nontarget organ uptake. Therefore, two new antimyosin imaging agents experimentally shown to potentially improve dosimetry, shorten time from injection to imaging or decrease nonspecific cell binding were evaluated in a primate cardiac transplant model. The two agents evaluated were polylysine 111In-antimyosin (0.023 mg Fab modified with a 3.3 kd polymer of polylysine and labeled with 111In) and 99mTc-antimyosin (0.5 mg Fab' antimyosin labeled using the RP-1 ligand technique). A total of eight baboons were studied: three with heterotopic (cervical) xenographs, three with orthotopic allographs and two control animals. Each animal was injected first with 12-23 mCi of 99mTc-RP-1 antimyosin and 5-16 hr after completion of imaging, was injected with 0.72-1.88 mCi of 111In-polylysine antimyosin (PIs) and reimaged 12-48 hr later. The imaging results were compared to the histology of the animals. Biexponential curves were fit to the blood sample data and rate constants were determined and expressed as T1/2 values. There were no significant differences between the two agents in either the early fast components or the late slow components. On planar imaging, there was blood-pool activity at 10-12 hr postinjection of both agents, but by 16-24 hr postinjection, blood pool was negligible on the 111In-PIs scans. Both agents were concentrated in the rejected cardiac tissue. The slow blood-pool clearance combined with the 6 hr half-life of 99mTc-RP-1 AMA make this agent less promising for detection of diffuse myocardial uptake than 111In Fab modified with polylysine.     

Risk factors for early termination of breast feeding in Brazil

A prospective study was undertaken to identify possible factors related to the duration of breast feeding. Two hundred and thirty-eight mothers who had delivered normal single babies with birth weights greater than 2.5 kg and had initiated breast feeding were randomly selected at the maternity hospital, Hospital de Clinicas de Porto Alegre, Brazil, and followed by mail questionnaires until termination of breast feeding, or until the end of the first year. If no reply was received, telephone contact or home visits were made. The group of mothers who stopped breast feeding prior to the end of the third month was compared with those who extended breast feeding beyond three months with respect to socioeconomic, biological, environmental, medical and psychological factors. The variables with a significant coefficient of association with early termination of breast feeding were maternal education, past experience with breast feeding, help of a maid, help with housework provided by a relative, breast feeding orientation during prenatal care and encouragement from the husband. These factors act simultaneously, with interactions among them.     

Angiotensin II in arterial and renal venous plasma and renal lymph in the dog

Angiotensin II was determined by radioimmunoassay in systemic arterial, pulmonary arterial, and renal venous plasma and in renal hilar lymph in dogs. Levels of the peptide were determined prior to and during progressive graded hemorrhage or reduction in renal perfusion pressure. Levels of angiotensin II in plasma consistently rose during transit through the lung indicating pulmonary conversion of angiotensin I to angiotensin II. On the other hand, angiotensin II in the renal vein plasma was less than that in arterial plasma indicating renal extraction of the peptide from plasma. When renal hilar lymph was sampled under similar conditions, angiotensin II in lymph was consistently higher than that in arterial or renal venous plasma. Furthermore, in some experiments angiotensin II in lymph increased at a time when the concentration in plasma was undetectable. No evidence was found to indicate that angiotensin II in plasma entered renal lymph. It was concluded that angiotensin II levels in lymph reflected the concentration of angiotensin II in renal tissue. The data further suggested that angiotensin II is partially removed from arterial plasma by hydrolysis during transit through the kidney.     

Persistent pleural effusions in primary systemic amyloidosis: etiology and prognosis

BACKGROUND: Restrictive cardiomyopathy frequently complicates primary systemic amyloidosis (AL), yet only a small number of these patients develop large pleural effusions refractory to diuretic therapy and thoracentesis. We hypothesized that disruption of pleural function by amyloid deposits underlies persistent pleural effusions (PPEs) in patients with AL disease. METHODS: We performed a retrospective study of AL patients with and without PPEs who had been referred to Boston University between 1994 and 2001. The presence of PPEs was defined by a failure to resolve the condition with thoracentesis and aggressive diuresis. AL cardiomyopathy patients without pleural effusions constituted the control (cardiac) group. Indexes of plasma cell dyscrasia, nephrotic syndrome, thyroid function, and echocardiographic measures of left and right ventricle performance were compared between groups. When available, closed needle biopsies and autopsy specimens of parietal pleura were examined for amyloid deposits. RESULTS: Among 636 patients with AL, 35 PPE patients underwent a median of three thoracenteses each. No statistical differences were found between the PPE and cardiac groups in echocardiographic measures of septal thickness, left ventricular systolic function, or diastolic compliance. Right ventricular (RV) hypokinesis occurred more often in PPE patients; however, nearly half of this group had normal RV systolic function. Renal function, plasma protein levels, and thyroid function were the same between groups. Nephrotic range proteinuria (ie, > 3 g/d) was more prevalent in the cardiac group than in the PPE group (44% vs 26%, respectively; p = 0.057). All pleural biopsies in the PPE group (six biopsies) revealed amyloid deposits. Autopsy samples of parietal pleura were negative for disease in two cardiac patients. Eighteen patients had chest tubes placed, and 11 underwent pleurodesis. PPE signaled limited survival among patients who were ineligible for treatment. Untreated PPE patients lived a median 1.8 months vs 6 months for untreated cardiac patients (p = 0.031). Survival after intensive chemotherapy and autologous stem cell transplantation was comparable in the PPE and cardiac groups (21.8 vs 15.6 months, respectively; p = 0.405). CONCLUSION: In AL patients with cardiac amyloid, neither echocardiographic measures of ventricular function nor the degree of nephrosis distinguished those patients with PPEs. We conclude that pleural amyloid infiltration plays a central role in the creation and persistence of pleural effusions among patients with AL.