Formation of double-walled microtubules and multilayered tubulin sheets by basic proteins

Some basic proteins enable microtubule protein to form special assembly products in vitro, known as double-walled microtubules. Using histones (H1, core histones) as well as the human encephalitogenic protein to induce the formation of double-walled microtubules, we made the following electron microscopic observations: (1) Double-walled microtubules consist of an "inner" microtubule which is covered by electron-dense material, apparently formed from the basic protein, and by a second tubulin wall. (2) The tubulin of the second wall seems to be arranged as protofilaments, surrounding the inner microtubule in a helical or ring-like manner. (3) The surface of double-walled microtubules lacks the projections of microtubule-associated proteins, usually found on microtubules. (4) In the case of protofilament ribbons (incomplete microtubules), H1 binds exclusively to their convex sides that correspond to the surface of microtubules. Zn2+-induced tubulin sheets, consisting in contrast to microtubules of alternately arranged protofilaments, are covered by H1 on both surfaces. Furthermore, multilayered sheet aggregates appeared. The results indicate that the basic proteins used interact only with that protofilament side which represents the microtubule surface. In accordance with this general principle, models on the structure of double-walled microtubules and multilayered tubulin sheets were derived.

Pathogenetic role of HIV infection in Kaposi's sarcoma of equatorial East Africa

Thirty residents of north-central Tanzania with various forms of Kaposi's sarcoma (KS) were evaluated. The absolute number of peripheral blood OKT4 lymphocytes in patients and Tanzanian control subjects tended to be low (in comparison with healthy young American adults), and many had inverted T4/T8 ratios. Plasma polyclonal beta- and gamma-globulin concentrations were increased in many patients with KS and in control patients in Tanzania with chronic dermatopathies, but not in African hospital employees and patients undergoing elective surgery. Three of nine patients with locally aggressive KS possessed antibodies to human T-cell lymphotropic virus type III/lyphadenopathy-associated virus (HIV), but none had evidence of the acquired immunodeficiency syndrome (AIDS) or the AIDS-related complex. Three patients with disseminated, rapidly progressive KS and high HIV-antibody titers had an immunologic and clinical picture consistent with AIDS. Two of 13 patients with the classic plaque/nodular form of KS had low plasma titers of HIV antibody, but the significance of these serologic findings is not known. The evidence suggests that HIV plays a role in the pathogenesis of some cases of KS in East Africa, but most patients with KS in East Africa have no evidence of overt immunologic deficiency or HIV infection.

Congenital scoliosis and urinary tract abnormalities: are intravenous pyelograms necessary?

One hundred patients with a diagnosis of congenital scoliosis were reviewed with regard to their urologic history, chemistries, and excretory urography. A 40% incidence of urologic abnormality was found in these asymptomatic patients. Twenty-five additional patients were evaluated by excretory urography and ultrasonography. Of six patients identified by ultrasonography as having abnormalities five had results confirmed by excretory urography. Urologic evaluation of all patients with congenital scoliosis is recommended; however, diagnostic ultrasonographic evaluations of the urinary tract have proven to be an acceptable alternative as an initial screening modality.

Subdural hematoma in systemic lupus erythematosus: report and review of the literature

A patient with systemic lupus erythematosus (SLE) and subdural hematoma is described. Pathophysiological concepts are discussed and a link between this lesion and active SLE is suggested. The disastrous consequences of failure to recognize subdural hematoma in this context is emphasized.

Diagnostic imaging in pediatrics: the state of the art

The results of the study panels, both at national and international levels, have shown that much can be done to increase the efficiency and efficacy of diagnostic imaging in all areas of medical practice including pediatrics. Much remains to be done, however. The work that has been done must be expanded into a thorough investigation of the safety, yield, and cost of diagnostic imaging. It is the responsibility of all physicians to continue efforts toward more rational use of diagnostic imaging at all levels of society and to make sure that established guidelines are implemented. Flexibility in attitudes, cooperation between clinician and radiologist, and a willingness to learn and keep up with advances are essential to this process--not only to improve the benefits from diagnostic imaging, but to preserve the ability of society to pay for it. Those who would proclaim that this or that recommendation is the "last word" must realize that half of what is said today may well be proven false 10 years from now, and, further that we have no way of knowing what techniques and imaging approaches will comprise that half, nor should the imaging "standards" be self-serving. Guidelines drawn up in an academic vacuum where all imaging techniques are readily available may have little practical application in pediatric practice and impact on health care in areas of the world where diagnostic imaging, if available at all, will consist only of basic radiographic imaging. At the same time, experience gained in countries using all advanced imaging modalities must be shared with less fortunate nations: such knowledge may have important implications for even the most basic radiographic studies.(ABSTRACT TRUNCATED AT 250 WORDS)

Imaging of neuroblastoma: an overview

This review article briefly describes the pathology, clinical features, prognosis, and treatment of neuroblastoma. The emphasis is on applications of newer diagnostic modalities (sonography, nuclear scintigraphy, computed tomography) for imaging and staging. The potential role of magnetic resonance imaging and spectroscopy is discussed.

Acute median nerve compression by haemorrhage from acute myelomonocytic leukaemia

A 61-year-old male receiving treatment for acute myelomonocytic leukaemia (AMML) developed weakness and sensory loss in the thumb, index and middle finger and half of the ring finger of the left hand as a result of a spontaneous haemorrhage into the carpal tunnel and forearm, an unusual cause of median nerve compression. These findings were confirmed by CT scanning and post-mortem examination. This is the first report of spontaneous haemorrhage occurring in a patient with AMML.

Extracranial cribside sonography in infants

In 29 real-time ultrasonic studies of infants in the intensive care nursery, the technique either accurately diagnosed or led directly to the correct diagnosis in 27 (93%). Twenty-four of these infants had suspected abnormality in the abdomen or pelvis, three had congestive heart failure and bruits, one had respiratory distress and an opacified hemithorax on chest roentgenogram, and one was a child with ambiguous genitalia in whom sonography identified a uterus. We suggest that portable, real-time ultrasonography is an ideal modality with which to study seriously ill infants whose medical condition precludes transport to the radiology department.

Use of computed tomography in pediatric oncology

Computed tomography (CT) has dramatically changed the imaging of pediatric oncologic disease. CT precisely displays and characterizes cross-sectional anatomic pathology. This provides important information for diagnosing and staging tumors in infants and children. The principles, techniques, and indications for computed tomography in the evaluation of pediatric extracranial tumors are reviewed in this article. Selected applications of computed tomography for pediatric tumors of the mediastinum, chest wall, lung parenchyma, abdomen, pelvis, and extremities are discussed and illustrated.

Congenital saccular anterior urethral diverticulum

Congenital saccular diverticulum is an uncommon abnormality of the anterior urethra in the male. In seven cases (6 infants and an 8-year-old boy) the diverticulum was well demonstrated by voiding cystourethrography and/or retrograde urethrography. In patients with saccular anterior urethral diverticulum, contrast material fills an oval outpouching of the ventral aspect of the anterior urethra. The clinical presentation, unique radiologic appearance, and differential diagnostic considerations are reviewed.

Localization of the site of urinary tract infections with the bladder washout test

The data from 100 bladder washout studies on pediatric patients have been analyzed to derive criteria for interpretation of this test and to define the limitations of this procedure in localization of the site of urinary tract infections. Using the bladder washout test, infection of the upper urinary tract is characterized by an abrupt increase in the concentration of bacteria in urinary specimens collected following urinary bladder sterilization. Infection limited to the lower urinary tract is characterized by scant if any bacterial growth in the specimens of urine collected following bladder sterilization. The site of infection may be incorrectly localized to the lower urinary tract or classified as not determined in patients with scant or intermittent renal bacteriuria.

Pulmonary sarcoidosis in childhood

Clinical and radiologic characteristics of pulmonary sarcoidosis in 26 children are presented. Initial nonspecific symptomatology and decreased pulmonary function are almost invariably accompanied by radiologic evidence of pulmonary disease. Bilateral hilar lymphadenopathy frequently associated with bilateral paratracheal adenopathy is characteristic. Other mediastinal lymphadenopathy (subcarinal, anterior, and posterior) is sporadically present, and is invariably associated with the more specific bilateral patterns of thoracic adenopathy. Pulmonary parenchymal involvement is common and predominantly appears radiographically as small irregular densities. Pleural effusion, pneumothorax, and cardiomegaly are unusual findings. Extrathoracic radiographic manifestations are uncommon. Lytic lesions of the tubular bones of the hands and feet are rare in childhood.

The dietary chloride deficiency syndrome

Chronic depletion of body chloride developed in a group of infants ingesting a diet consisting almost exclusively of chloride deficient Neo-Mull-Soy. Ten of the 12 infants were on this diet three to five months before loss of appetite, failure to thrive, muscle weakness, and lethargy led to a diagnostic evaluation. The outstanding laboratory features were severe hypokalemic metabolic alkalosis, low urinary chloride concentrations (< 10 mEq/liter), and erythrocyturia. There was marked decrease in weight for age in all 12 infants. Head circumference for age had decreased in five of six and length for age in five of ten infants for whom earlier measurements were available. The biochemical abnormalities reverted to normal following dietary supplementation with either sodium or potassium chloride. Appetite, affect, and muscle strength improved, and weight gain resumed. Head circumference for age has moved toward the percentile level present prior to starting Neo-Mull-Soy in all instances. With one exception, length measurements show a similar pattern. The erythrocyturia has decreased or vanished. Chloride deficiency led to contraction of the extracellular volume and the substitution of poorly reabsorbable anions for readily reabsorbable chloride. These alterations caused development of the negative hydrogen ion and potassium balances which led to the hypokalemic metabolic alkalosis.

Ultrasonic diagnosis of obstructed renal duplication and ureterocele

The diagnoses of complete obstruction in a duplicated renal collecting system and ureterocele can be made with a high degree of confidence by ultrasound. Two children presenting with abdominal masses were examined by gray scale ultrasonography which demonstrated large cystic masses dorsal to and displacing the lower pole of the kidney ventrally and laterally. In one patient the dilated ureter terminated in a ureterocele. Ultrasonography is the appropriate imaging modality for this disease process, though it generally becomes the complementary study to excretory urography in the diagnosis of an obstructed duplicated system. The dilated pelvis and ureter can be imaged to ultrasonography even when their presence is only implied on an excretory urogram. Finally, the cystic nature of a ureterocele, as well as its relationship to the ureter and bladder, makes ultrasonography an ideal technic for evaluating this anomaly.

Radiological observations during transpyloric tube feeding in infants of low birth weight. Perforation of the duodenum and variations in normal duodenal anatomy

Perforation of the duodenum is a serious complication of transpyloric tube feeding in infants of low birth weight. Polyvinyl chloride and (less commonly) silicone tubes have been implicated. Altered radiographic configuration of the tube in the region of the superior or inferior flexure, associated with clinical deterioration, pneumoperitoneum, peritonitis, or a retroperitoneal fistula, is diagnostic of duodenal perforation. The configuration of the tube may vary during uncomplicated transpyloric alimentation and is frequently incompatible with the expected anatomical course. Contrast examination may demonstrate normal anatomy or mobility of the distal duodenal loop as an adaptation to rigidity of the tube. The possibility of perforation appears to be increased at or adjacent to the flexures.

Integrated imaging for the evaluation of the urologic diseases of childhood

The rational selection of imaging modalities for the diagnosis of renal and adrenal masses in children is discussed with a view toward obtaining an accurate assessment of pathologic changes with the least amount of stress and expense to the patient. The integration of the results of these tests in specific clinical settings is also described.