A strain of Clostridium sporogenes, an anaerobic bacterium, isolated from sewage in New York City synthesizes two constitutive enzymes with action on steroid molecules: (i) an enzyme capable of selectively acetylating the 21-hydroxyl function of certain steroids and (ii) the corresponding esterase. Under our experimental conditions the enzymes have a strict structural requirement for 3-keto-4-ene and C-20-keto or 20 alpha-hydroxyl group and convert their respective substrates to a mixture of free and acetylated products.

Acetylation↗

PubMedDate not supplied

Demonstration of postural effects and layering by cranial computed tomography.

The superb contrast resolution of computed tomography permits visualization of layering of fluid components of varying densities in tumors and hematomas which cannot be observed with conventional radiographic techniques. Layering confirms the fluid nature of a cystic tumor and suggests the possibility of draining the fluid contents in an effort to reduce mass effect. Verification of layering is achieved by noting shifting of the dependent material with axial rotation of the patient. While unusual, this finding is significant because solid tumors occasionally show low densities simulating fluid. The presence of layering of intraventricular of subdural blood implies that the blood is fluid rather than clotted and therefore removal by aspiration will be possible.

Adult↗

PubMedDate not supplied

CT evaluation of Haemophilus influenzae meningitis with clinical and pathologic correlation.

Ten proven cases of Haemophilus influenzae meningitis have been reviewed, in which all had CT scans during their first 3 weeks of illness. An attempt was made to correlate the neuropathologic basis of the disease with the CT findings. Progression of the CT changes with the course of illness and treatment is emphasized. Usual indications for CT imaging of the brain in patients with meningitis are: detection of subdural empyema or effusion, hydrocephalus, infarct, cerebritis and abscess. Widespread cerebral damage can be more fully evaluated with iodine contrast infusion if clinically indicated. CT scanning has proven to be a valuable indicator of such complications and useful predictor of clinical recovery or residual neurologic sequelae.

Adult↗

PubMedDate not supplied

Retrosternal epiphyseal disruption of medial clavicle: case and review in children.

Retrosternal dislocations of the clavicle have been reported previously in adults throughout the orthopedic literature. However, in children few cases have been noted in either the pediatric, emergency, or orthopedic literature. The potential for great vessel injury as well as acute airway compromise makes the retrosternal disruption of the sternoclavicular joint a surgical emergency that must be diagnosed quickly. Diagnosis is enhanced by the cephalic tilt view and by computed tomography (CT scan), as planar x-ray and tomography do not always reveal this potentially life-threatening condition. Surgical consultation must be sought acutely; however, management may need to begin prior to definitive repair. Emergency management begins by suspecting the injury, and with immediate airway and circulatory support for the patient.

Adolescent↗

PubMedDate not supplied

Retinal ganglion cells lose response to laminin with maturation.

The decisive role played by adhesive interactions between neuronal processes and the culture substrate in determining the form and extent of neurite outgrowth in vitro has greatly influenced ideas about the mechanisms of axonal growth and guidance in the vertebrate nervous system. These studies have also helped to identify adhesive molecules that might be involved in guiding axonal growth in vivo. One candidate molecule is laminin, a major glycoprotein of basal laminae which has been shown to induce a wide variety of embryonic neurones to extend neurites in culture. Moreover, laminin is found in large amounts in injured nerves that can successfully regenerate but is absent from nerves where regeneration fails. However, it is unclear to what extent the mechanisms that regulate axonal regeneration also operate in the embryo when axon outgrowth is initiated. Here we have examined the substrate requirements for neurite outgrowth in vitro by chick embryo retinal ganglion cells, the only cells in the retina to send axons to the brain. We show that while retinal ganglion cells from embryonic day 6 (E6) chicks extend profuse neurites on laminin, those from E11 do not, although they retain the ability to extend neurites on astrocytes via a laminin-independent mechanism. This represents the first evidence that central nervous system neurones may undergo a change in their substrate requirements for neurite outgrowth as they mature.

Animals↗

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Oxygen and placental development during the first trimester: implications for the pathophysiology of pre-eclampsia.

During early pregnancy, placentation occurs in a relatively hypoxic environment which is essential for appropriate embryonic development. Intervillous blood flow increases at around 10-12 weeks of gestation and results in exposure of the trophoblast to increased oxygen tension (PO2). Prior to this time, low oxygen appears to prevent trophoblast differentiation towards an invasive phenotype. In other mammalian systems, oxygen tension effects are mediated by hypoxia inducible factor-1 (HIF-1). We found that the ontogeny of HIF-1alpha subunit expression during the first trimester of gestation parallels that of transforming growth factor-beta3 (TGFbeta3), an inhibitor of early trophoblast differentiation. Expression of both molecules is high in early pregnancy and falls at around 10 weeks of gestation when placental PO2 levels are believed to increase. Antisense-induced inhibition of HIF-1alpha inhibited the expression of TGFbeta3, and stimulated extravillous trophoblast (EVT) outgrowth and invasion. Of clinical significance we found that TGFbeta3 expression was increased in pre-eclamptic placentae when compared to age-matched controls. Significantly, inhibition of TGFbeta3 by antisense oligonucleotides or antibodies restored the invasive capability to the trophoblast cells in pre-eclamptic explants. We speculate that if oxygen tension fails to increase, or trophoblasts do not detect this increase, HIF-1alpha and TGFbeta3 expression remain high, resulting in shallow trophoblast invasion and predisposing the pregnancy to pre-eclampsia. Effective fetal-maternal interactions during early placentation are critical for a successful pregnancy. Optimal placental perfusion requires the controlled invasion of trophoblast cells deep into the decidua to the spiral arteries. Trophoblast stem cells, also referred to as cytotrophoblast cells, reside in chorionic villi of two types, floating and anchoring villi. Floating villi, which represent the vast majority of chorionic villi, are bathed in maternal blood and primarily perform gas and nutrient exchange for the developing embryo. During early placentation, cytotrophoblast cells in the floating villi proliferate and differentiate by fusing to form the multinucleate syncytiotrophoblast layer. Cytotrophoblast cells in anchoring villi either fuse to form the syncytiotrophoblast layer, or break through the syncytium at selected sites and form multilayered columns of non-polarized extravillous trophoblast cells, which physically connect the embryo to the uterine wall (Figure 1). The extravillous trophoblast cells invade into the uterine wall as far as the first third of the myometrium and its associated spiral arteries, where they disrupt the endothelium and the smooth muscle layer and replace the vascular wall. This results in the conversion of the narrow calibre arteries into distended uteroplacental arteries, thereby increasing blood flow to the placenta and allowing an adequate supply of oxygen and nutrients to the growing fetus. The invasive activity of the extravillous trophoblast cells is at a maximum during the first trimester of gestation, peaking at around 10-12 weeks and declining thereafter. Insufficient invasion contributes to the development of pre-eclampsia, which often results in fetal intrauterine growth restriction, maternal hypertension and proteinuria. In contrast, unrestricted invasion is associated with premalignant conditions, such as invasive mole, and with malignant choriocarcinoma. Invading trophoblast cells undergo striking and rapid changes in cellular functions that are temporally and spatially regulated along the invasive pathway (Figure 1) (Cross, Werb and Fisher, 1994. The formation of the anchoring villi is accompanied by changes in synthesis and degradation of extracellular matrix proteins and their receptors, and changes in the spatial distribution of extracellular matrix proteins, as well as changes in the expression of adhesion molecules (Damsky, Fitzgerald and

DNA-Binding Proteins↗

PubMedDate not supplied

Radiation dose enhancement in tumors with iodine.

The loading of tissue with iodine can result in the enhancement of the radiation dose absorbed from low-energy x-ray or gamma ray sources. We have explored the potential of this phenomenon for radiation therapy. We have demonstrated the effect of iodine concentration and radiation quality on this dose enhancement in lymphocytes, we have calculated the effect of such enhancement on depth dose distributions in the brain, we have estimated the iodine content in two human brain tumors during computerized tomography (CT) scans, we have studied the dispersion of the iodine contrast media after direct injection into rabbit tumors, and we have demonstrated that the combination of x-ray and contrast media injection is far more effective than either agent alone in causing the regression of mouse tumors. These results suggest that there may be a therapeutic advantage from loading tumors with iodine and treating them with low-energy photons.

Animals↗

PubMedDate not supplied

Computerized tomography scanning of the temporal bone.

Computerized tomography (CT) scanning has reached a degree of sophistication that requires alteration of technical factors to demonstrate different parameters of temporal bone pathology. The techniques for pontocerebellar angle display, eustachian tube, middle ear pathology, and overall temporal bone display are quite different. Close cooperation between the radiologist and otologic surgeon are required for optimal use of CT scanning advances.

Adult↗

PubMedDate not supplied

Anesthetic considerations for cerebral computer tomography.

Cerebral computer tomography is a recently introduced neuroradiologic procedure involving tomographic x-rays of horizontal brain sections. Although most adults undergo the procedure without anesthesia, children and uncooperative adults must be given general anesthesia for absolute immobility. Of 84 procedures under general anesthesia, 10 employed ketamine, 6 used oral chloral hydrate; 60, endotracheal anesthesia enflurane or halothane; 7 used combinations of various sedatives. One was performed with local anesthesia standby. Ketamine and heavy sedation were found to be totally unsatisfactory because of airway problems and unpredicatability of motion, which produced image artifacts. General endotracheal anesthesia with either halothane or enflurane in N2O-O2 was found most satisfactory because of better control of airway and prevention of motion.

Adult↗

PubMedDate not supplied

Sin nombre virus (SNV) Ig isotype antibody response during acute and convalescent phases of hantavirus pulmonary syndrome.

Serum samples from 22 hantavirus pulmonary syndrome (HPS) patients were tested for Sin Nombre virus (SNV)-reactive antibodies. In the acute phase of HPS, 100% and 67% of the samples tested positive for SNV-specific immunoglobulin (Ig) M and IgA, respectively. Among the virus-specific IgG antibodies, the most prevalent were IgG3 (in 97% of samples), followed by IgG1 (70%), IgG2 (30%), and IgG4 (3%).

Acute Disease↗

PubMedDate not supplied

Parameters of in vitro 21-dehydroxylation of deoxycorticosterone by human fecal flora.

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Adult↗

PubMedDate not supplied

Energy demand of cardioplegically perfused human hearts.

Human adult hearts with aortic valve disease (n = 20) and hypertrophic obstructive cardiomyopathy (n = 1) were perfused intraoperatively with cold histidine buffered Bretschneider solution. During a seven minute cardioplegic perfusion the temperature level, the electrolyte level, the resistance of the left (LCA) and right coronary artery (RCA), and myocardial O2 consumption were analysed. Equilibration of K+ was terminated shortly after the start of the perfusion while Na+ equilibration lasted for about 5 minutes. Resistance of RCA did not change significantly, but that of the LCA was diminished significantly (p less than 0.025) within the perfusion period indicating a delayed washout of calcium from the extracellular space. Myocardial O2 consumption was reduced from 2.71 ml/min (1. minute) to 1.51 ml/min (4. minute) to 0.93 ml/min (7. minute) although the temperature had reached a low level after 3 minutes. The difference between 4. to 7. minutes is significant (p less than 0.001). By our results it is concluded that in adult hearts high-volume cardioplegic perfusion at a flow rate of 1 ml/min X gm at a perfusion pressure of 40 to 50 mmHg should be performed for at least 6 to 7 minutes to achieve a sufficient intra-ischemic myocardial protection.

Adult↗

PubMedDate not supplied

Detection of Australia antigen (hepatitis associated antigen) in blood serum and plasma.

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Antigen-Antibody Reactions↗