Pulmonary embolism after hip or knee replacement: postoperative changes on pulmonary scintigrams in asymptomatic patients

Serial pulmonary imaging has proved to be effective in the evaluation of patients undergoing total joint arthroplasty. A clinical dilemma arises in asymptomatic patients whose postoperative pulmonary images differ from the preoperative images. The authors prospectively evaluated 403 patients with serial imaging to determine the significance of changed postoperative images in asymptomatic patients undergoing total hip or knee arthroplasty. Twenty-two (5.5%) patients had significant changes on postoperative images. Seventeen were asymptomatic; all but one underwent pulmonary angiography. Documented pulmonary emboli were demonstrated in 100% of patients whose postoperative images changed to indicate a high probability of pulmonary embolism, 71% whose images changed to a moderate probability, and 0% whose images changed to indeterminate probability. Overall, pulmonary emboli occurred in 76% of all asymptomatic patients with significantly change postoperative images. Asymptomatic pulmonary embolism is a significant occurrence after total hip or knee repair, and a changed lung scan with appropriate clinical evaluation is an accurate indicator of pulmonary emboli in asymptomatic postarthroplasty patients.     

Cloning of cDNA coding for connective tissue activating peptide III from a human platelet-derived lambda gt11 expression library

We report here the cloning of the cDNA coding for platelet connective tissue-activating peptide-III (CTAP-III) from a lambda gt11 expression library prepared using messenger RNA (mRNA) isolated from human platelets. The open reading frame of the clone coded for a protein with 128 amino acid residues. Since the precursor of CTAP-III, platelet basic protein (PBP is 94 amino acids long, the 5'-translated region of the cDNA codes for a leader sequence 34 amino acids long. This leader sequence, like the sequence of mature CTAP-III, shows significant homology to the sequence of platelet factor 4 (PF4), the only other platelet specific alpha-granule protein cloned until now, from a human erythroleukemic (HEL) cell line-derived cDNA library. These leader sequences are probably critical for targeting such proteins to the alpha-granule. Northern blot hybridization with platelet and megakaryocyte mRNA shows a single species mRNA of approximately 0.8 kb, suggesting that the corresponding cDNA is full length. The cloning of platelet specific CTAP-III provides additional evidence for the platelet specificity of the cDNA library used.     

Hidden bias in the use of archival data.

Nonresponses in archival data may violate the missing-at-random assumption in ways difficult to detect. Standard methods of comparing sociodemographics of respondents and nonrespondents are inappropriate when the units of analysis are not also the individuals who maintain the archival record. Under these circumstances, the distribution of missing data may be correlated with the dependent variable and traits of the record keepers. This will distort relationships, especially when listwise deletion of missing values is used in multivariate analysis. Data are used from a large clinical chart study of mentally ill patients to demonstrate the process of identifying hidden bias and the implications of such bias.     

Sociodemographic Factors Associated with AIDS Knowledge in a Random Sample of University Students

A telephone survey was used to assess knowledge of the transmission, prevalence, and infectivity of acquired immunodeficiency syndrome (AIDS), and the safety of casual contact among 214 randomly selected university students. Males were more knowledgeable than females overall (odds ratio [OR], men/women = 4.8). Although most students understood the dangers of unprotected sex and intravenous needle sharing, up to 30% believed some kinds of casual contact (e.g., shared eating utensils) can transmit AIDS. Older students (greater than or equal to 23 yrs) were more knowledgeable than those 17 to 19 years old about the safety of casual contact (OR = 3.8). Students are in need of education programs that stress the ways AIDS is not transmitted. Since most students identified newspapers and television as their main sources of information, these may be effective vehicles for education efforts.     

Intravenous digital subtraction renal angiography: use in screening for renovascular hypertension

Intravenous digital subtraction renal angiography (DSRA) has been compared with conventional angiography only in small, selected series of hypertensive patients. The authors prospectively examined with intravenous DSRA 94 patients at increased risk for renovascular hypertension and compared these studies with conventional angiography. A stenosis of at least one main renal artery was identified with intravenous DSRA in 22 patients and confirmed in 20 patients. No significant stenoses were seen with conventional angiography in any of the 64 patients in whom lesions were not seen with intravenous DSRA. Since inadequate DSRA studies were considered positive for renal artery stenosis, the sensitivity of intravenous DSRA was 100% (25 of 25); specificity, 93% (64 of 69); positive predictive value, 83% (25 of 30); and negative predictive value, 100% (64 of 64). The authors conclude that intravenous DSRA is a sensitive test for identifying stenosis of the main renal arteries and is appropriate to use as a screening test among patients at increased risk for renovascular hypertension.     

Punishment modifies the effects of chlordiazepoxide and benzodiazepine receptors

Littermate groups of male albino rats responded under a procedure which generated comparable rates of punished and nonpunished responding. Chlordiazepoxide (3.0-30.0 mg/kg, IP) increased punished responding but had no effect on nonpunished responding. Homogenate receptor binding studies with [3H]Ro 15-1788 indicated increased benzodiazepine receptor binding in the striatum of rats who received shock. Moreover, a third group of rats exposed to noncontingent shock showed greater increases than those whose responses had been punished, suggesting that predictability and control of shock may have attenuated the effects of the noxious stimulus. Increased binding seen in the cerebellum, however, was related to the punishing effects of the electric shock since it occurred only in those animals receiving response-contingent shock. There were no changes in binding affinity in any of the brain regions tested. Site-specific alterations benzodiazepine receptors following electric footshock are related to the contingencies under which the noxious stimuli are administered. Furthermore, changes in benzodiazepine receptor binding may underlie the differential effects of benzodiazepine agonists on punished and nonpunished responding.     

Ultraviolet-B irradiation of platelets: a preliminary trial of efficacy

Prior studies established that ultraviolet-B light (UVB) irradiation of platelet concentrates (PCs) at appropriate doses can eliminate the mixed lymphocyte culture-stimulating and -responding capacity of lymphocytes in the PCs without adversely affecting in vitro platelet function. The in vivo recovery and survival and in vitro characteristics of UVB-irradiated platelets were investigated in paired studies. PCs were stored for 1 day and then exposed to UVB. Platelet recovery, survival, and function were comparable to those of nonirradiated platelets. Recovery and survival of platelets stored for 5 days before UVB exposure were decreased relative to controls, although they were considered clinically acceptable. Paired transfusion studies were also performed in seven thrombocytopenic patients by using platelets obtained by apheresis. Comparable posttransfusion platelet increments and bleeding time corrections were obtained with both irradiated and control (nonirradiated) platelets. It can be concluded that platelets survive and function relatively normally in vivo after UVB irradiation sufficient to abolish lymphocyte reactivity in mixed lymphocyte culture. Long-term studies of UVB-irradiated PCs are needed to assess their potential in reducing recipient alloimmunization.     

West Nile virus in the United States: an update on an emerging infectious disease

West Nile virus is a mosquito-borne flavivirus and human neuropathogen. Since the virus was recognized in New York City in 1999, it has spread rapidly across the United States, with human disease documented in 39 states and the District of Columbia. West Nile virus can cause a broad range of clinical syndromes, including fever, meningitis, encephalitis, and a flaccid paralysis characteristic of a poliomyelitis-like syndrome. Approximately one in 150 infections results in severe neurologic illness. Advanced age is the greatest risk factor for severe neurologic disease, long-term sequelae, and death. Physicians should consider West Nile virus infection when evaluating febrile patients who have unexplained neurologic symptoms, muscle weakness, or erythematous rash during late spring through early fall, or throughout the year in warm climates. West Nile virus infection has no characteristic findings on routine laboratory tests, although anemia, leukocytosis, or lymphopenia may be present. Testing for IgM antibody to West Nile virus in serum or cerebrospinal fluid (samples from the acute and convalescent phases, submitted at least two weeks apart) is the most common diagnostic method. Local or state health departments usually can perform the test within 24 to 36 hours of submission. Treatment is supportive. Prevention relies on comprehensive mosquito-control programs and measures to avoid mosquito bites, including the use of mosquito repellents containing N,N-diethyl-m-toluamide.