Focusing of a Rydberg Positronium Beam with an Ellipsoidal Electrostatic Mirror.

Slow atoms in Rydberg states can exhibit specular reflection from a cylindrical surface upon which an azimuthally periodic potential is imposed. We have constructed a concave mirror of this type, in the shape of a truncated oblate ellipsoid of revolution, which has a focal length of (1.50±0.01) m measured optically. When placed near the center of a long vacuum pipe, this structure brings a beam of n=32 positronium (Ps) atoms to a focus on a position sensitive detector at a distance of (6.03±0.03) m from the Ps source. The intensity at the focus implies an overall reflection efficiency of ∼30%. The focal spot diameter (32±1) mm full width at half maximum is independent of the atoms' flight times from 20 to 60 µs, thus indicating that the mirror is achromatic to a good approximation. Mirrors based on this principle would be of use in a variety of experiments, allowing for improved collection efficiency and tailored transport or imaging of beams of slow Rydberg atoms and molecules.

Ligand-induced movement of lymphocyte membrane macromolecules. II. Mapping of surface moieties.

Anti-immunoglobulin (Ig) coupled to ferritin or hemocyanin was used to map the distribution of Ig molecules on lymphocytes derived from bone marrow (B lymphocytes) by freeze-etching. The labeled anti-Ig was distributed all over the membrane in the form of random interconnected patches forming a lacy, continuous network. This was the pattern of lymphocytes labeled at 4 degrees C with the anti-Ig. After warming at 37 degrees C, the labeled molecules concentrated into a single area of the cell (forming the cap) and were rapidly internalized in small vesicles Freeze-etching showed close packing of the labeled molecules in the cap area. There was evidence that in the cap area the Ig molecules were exfoliated from the plane of the membrane, suggesting that the Ig may be superficial to the bilipid layer, or weakly anchored to the membrane. Similar studies were made using antibodies to histocompatibility antigens. Thymocytes were labeled with anti-H-2 and ferritin anti-Ig at 4 degrees C. Freeze-etching showed large patches scattered over the membrane and separated from each other by several thousand angstroms. This distribution may, in part, explain why H-2 antigens do not readily form a cap; the large patches are beyond the reach of even a double ligand (sandwich) reaction. The antigens that reacted with heterologous anti-lymphocyte globulin (ALG) were found in small noninterconnected clusters a few hundred angstroms apart. Such clusters presumably cannot be linked by a single antibody but can by a sandwich (ligand to ligand-antigen) reaction. In previous studies it was found that ALG antigens form a cap only after a sandwich reaction. Finally, the receptors for concanavalin A (Con A) were found in a lacy, irregular interconnected, random network. The spatial distribution of these moieties on the membrane may, in great part, determine their movement after reaction with one or two ligands.

Endothelial contraction induced by histamine-type mediators: an electron microscopic study.

Previous work has shown that endogenous chemical mediators, of which histamine is the prototype, increase the permeability of blood vessels by causing gaps to appear between endothelial cells. In the present paper, morphologic and statistical evidence is presented, to suggest that endothelial cells contract under the influence of mediators, and that this contraction causes the formation of intercellular gaps. Histamine, serotonin, and bradykinin were injected subcutaneously into the scrotum of the rat, and the vessels of the underlying cremaster muscle were examined by electron microscopy. To eliminate the vascular collapse induced by routine fixation, in one series of animals (including controls) the root of the cremaster was constricted for 2-4 min prior to sacrifice, and the tissues were fixed under conditions of mild venous congestion. Electron micrographs were taken of 599 nuclei from the endothelium of small blood vessels representing the various experimental situations. Nuclear deformations were classified into four types of increasing tightness (notches, foldsl closing folds, and pinches. In the latter the apposed surfaces of the nuclear membrane are in contact). It was found that: (1) venous congestion tends to straighten the nuclei in al groups; (2) mediators cause a highly significant increase in the number of pinches (P < 0.001), also if the vessels are distended by venous congestion; (3) fixation without venous congestion causes vascular collapse. The degree of endothelial recoil, as measured by nuclear pinches, is very different from that caused by mediators (P < 0.001). (4) Pinched nuclei are more frequent in leaking vessels, and in cells adjacent to gaps (P < 0.001); (5) mediators also induce, in the endothelium, cytoplasmic changes suggestive of contraction, and similar to those of contracted smooth muscle; (6) there is no evidence of pericyte contraction under the conditions tested. Occasional pericytes appeared to receive fine nerve endings. Various hypotheses to explain nuclear pinching are discussed; the only satisfactory explanation is that which requires endothelial contraction.

Hemoglobin as a tracer in hemodynamic pulmonary edema.

Stroma-free hemoglobin is an electron-opaque molecule useful as a tracer for the ultrastructural stuty of pulmonary capillary permeability. After this tracer was infused into the isolated pulmonary lobe of the dog, the endothelial junctions of the capillaries, as revealed by electron microscopy, act like distensible pores, thus allowing the tracer to escape when the pulmonary artery pressure was raised above 50 millimeters of mercury.

Steroid sulfatase of human leukocytes and epidermis and the diagnosis of recessive X-linked ichthyosis.

Patients with recessive X-linked ichthyosis, one of the inherited types of excessive stratum corneum cohesion, have deficient steroid sulfatase in fibroblasts grown from their dermis. Because of the expense and long period required to grow such cells, we have assayed this enzyme in peripheral blood leukocytes and found it to be undetectable in those from patients with this type of ichthyosis, but normal in those from patients with other hereditary or acquired types of ichthyosis. In addition, steroid sulfatase activity is less in leukocytes from women who are carriers of this disease than normal women, and this assay can be used to detect such carriers. Despite previous studies demonstrating that the gene for this enzyme escapes the inactivation of other x-chromosome genes, normal women have leukocyte steroid sulfatase activity only 1.3 times that of normal men, suggesting that some gene dosage compensation occurs. Normal human epidermis, the tissue most affected clinically, also expresses steroid sulfatase activity. The epidermal enzyme is similar in its subcellular localization, its molecular size, and kinetically to that of placenta, leukocytes, and fibroblasts.

Physical mapping of the serotonin 5-HT(7) receptor gene (HTR7) to chromosome 10 and pseudogene (HTR7P) to chromosome 12, and testing of linkage disequilibrium between HTR7 and autistic disorder.

The gene encoding the serotonin 5-HT(7) receptor (HTR7) has been considered as a candidate locus in several neuropsychiatric disorders, based on pharmacological evidence and ligand-binding studies. After determining over 3 kb of previously unpublished sequence from introns 1 and 2 of HTR7, a single base (C/T) polymorphism in the second intron of HTR7 was found. Allele-specific PCR was used to genotype the HTR7 marker in 53 trios consisting of subjects with autistic disorder and both parents. Using the transmission disequilibrium test (TDT), no evidence of preferential transmission of either allele was found (TDT chi(2) = 0.252, p = 0.602). Sequence data obtained from both intron 1 and intron 2 of HTR7, and from the 5-HT(7) pseudogene (HTR7P), was used to confirm localization of HTR7 to 10q23 and HTR7P to 12p13 using radiation hybrid analyses.

Predictors of outcome in cardiac surgical patients with prolonged intensive care stay.

OBJECTIVE: To determine the predictors of outcome in cardiac surgical patients with prolonged ICU stay. DESIGN: Inception cohort with retrospective chart review. SETTING: Adult cardiovascular ICU. PATIENTS: All patients admitted after cardiac surgery who stayed in ICU for at least 14 consecutive days. INTERVENTIONS: Collection of data, including preoperative demographics, comorbidity, routine laboratory testing, surgical procedure, duration of cardiopulmonary bypass and aortic cross-clamping, postoperative requirement for transfusion and intra-aortic balloon counterpulsation, and postoperative indexes of organ dysfunction 14 and 28 days after surgery. An organ failure score (OFS) was calculated for days 1, 14, and 28. OUTCOME MEASURES: Hospital mortality. RESULTS: One hundred forty-one of 324 (43.5%) ICU admissions lasting at least 14 days resulted in hospital mortality. Seventy-four of 166 (45%) ICU admissions lasting at least 28 days resulted in hospital mortality. Preoperative demographics, morbidity, and indexes of organ failure in the first 24 h after surgery were not predictive of hospital mortality. Indexes of organ failure predictive of hospital death at 14 days included requirement for epinephrine infusion, diminished Glasgow coma scale, requirement for dialysis, greater value of BUN, lower value of creatinine, greater value of bilirubin, greater value of arterial PCO2, lower platelet count, and lower value of serum albumin. After a 28-day stay in ICU, the indexes of organ failure predictive of hospital mortality included requirement for dopamine or norepinephrine infusions, diminished Glasgow coma score, greater value of bilirubin, greater value of arterial PCO2, lower value of serum albumin, and advanced age. The area under the receiver operating characteristic curve for the OFS on day 1 was 0.55+/-0.04 (p=0.12), on day 14 it was 0.75+/-0.03 (p<0.0001), and on day 28 it was 0.76+/-0.04 (p<0.0001). CONCLUSION: Preoperative health status and early organ failure were not predictive of late hospital mortality. The pattern of late organ failure associated with hospital mortality changed with time.

Association between postoperative hypothermia and adverse outcome after coronary artery bypass surgery.

BACKGROUND: We examined the effect on outcome of mild hypothermia (< 36 degrees C) upon intensive care unit (ICU) admission on patient outcome after coronary artery bypass grafting (CABG) with cardiopulmonary bypass (CPB). METHODS: We performed a retrospective database analysis of 5,701 isolated CABG patients requiring CPB, operated upon from January 1995 to June 1997. Patients were classified as either hypo- (< 36 degrees C) or normothermic (> or = 36 degrees C) upon ICU admission. ICU admission bladder core temperature (BCT) versus outcome was evaluated. Outcome measures included mortality, resource utilization (mechanical ventilation time, ICU and hospital length of stay, and postoperative packed red blood cell transfusion), and major morbidity (cardiac, renal, neurologic, or major infection). RESULTS: Overall, patients admitted to the ICU with BCT < 36 degrees C had a significantly greater mortality (p = 0.02), prolonged mechanical ventilation (p = 0.007), packed red blood cell transfusion (p = 0.001), ICU (p = 0.01), and hospital (p = 0.005) length of stay. CONCLUSIONS: BCT of less than 36 degrees C, upon ICU admission, has a significant association with adverse outcome after CABG with CPB. M An __ Tl QA_7_t-0

Osteoarthrosis of the atlanto-axial joints. Long-term follow-up after treatment with arthrodesis.

We evaluated the results for fifteen patients in whom symptomatic osteoarthrosis of the atlanto-axial joints had been treated with an atlanto-axial or occipitocervical arthrodesis between 1973 and 1990. Thirteen patients had long-term follow-up (average duration, seven years and two months; range, four years and two months to nineteen years and two months). The two remaining patients had died: one, four days postoperatively, from a cardiopulmonary arrest, and the other, one year and eight months postoperatively, from complications related to bladder cancer. Preoperatively, all fifteen patients reported pain in the occipitocervical region that increased with any attempt at rotation of the neck and was unresponsive to immobilization with a collar and to analgesics. The average duration of the symptoms before the arthrodesis was three years. One patient had acute quadriparesis. All patients had radiographic evidence of oesteoarthrosis involving the lateral atlanto-axial articulations. Four patients had atlanto-axial instability with an average of five millimeters (range, three to ten millimeters) of motion at the anterior atlanto-odontoid interval. Six patients had an associated spontaneous subaxial fusion, which was secondary to osteoarthrosis in five; three of the five also had atlanto-axial instability. Fourteen patients were managed with a posterior arthrodesis and one, with an anterior transoral arthrodesis. The procedures were performed to relieve pain, to stabilize the atlanto-axial joints, and to restore neurological function. Of the fourteen patients who were followed, thirteen had a solid fusion and one had a stable pseudarthrosis. The patient who had quadriparesis recovered. At the latest follow-up evaluation, thirteen patients had an excellent result and one had a fair result as determined with use of a modification of the criteria of Robinson et al. There were no poor results. Atlanto-axial arthrodesis can effectively relieve occipitocervical pain and correct atlanto-axial instability secondary to osteoarthrosis.

Postoperative cerebrospinal-fluid fistula associated with erosion of the dura. Findings after anterior resection of ossification of the posterior longitudinal ligament in the cervical spine.

Of twenty-two patients who had had anterior decompression of the spinal canal for ossification of the posterior longitudinal ligament and cervical myelopathy, seven had absence of the dura adjacent to the ossified part of the ligament. The spinal cord and nerve-roots were visible through this defect. Although the arachnoid membrane appeared to be intact and watertight in most patients, a cerebrospinal-fluid fistula developed postoperatively in five, and three had a second operation to repair the defect in the dura. On the basis of this experience, we recommend use of autogenous muscle or fascial dural patches, immediate lumbar subarachnoid shunting, and modification of the usual postoperative regimen, such as limitation of mechanical pulmonary ventilation to the shortest time that is safely possible and use of anti-emetic and antitussive medications to protect the remaining coverings of the spinal cord when the dura is found to be absent adjacent to an ossified portion of the posterior longitudinal ligament in the cervical spine.

Destructive spondyloarthropathy of the cervical spine in patients with chronic renal failure.

STUDY DESIGN: Eleven patients with chronic renal failure and destructive spondyloarthropathy of the cervical spine were evaluated with plain radiographs, flexion-extension views, computed tomography myelogram, or magnetic resonance imaging to determine the results of surgical and nonsurgical treatment. OBJECTIVES: To determine if cervical spine fusion is an effective method of treatment for patients with chronic renal failure and destructive spondyloarthropathy. SUMMARY OF BACKGROUND DATA: Several reports have described the pathogenesis and appearance of this condition, but little has been reported about the orthopedic management of destructive spondyloarthropathy of the cervical spine. METHODS: Three patients had no spinal surgery, three patients had laminectomies alone, three patients had laminectomies with anterior fusions, and two patients had laminectomies with posterior fusions. Radiographs, computed tomography myelograms, and magnetic resonance images were evaluated to determine the results of treatment. Histologic examinations were performed in two patients. RESULTS: Patients with laminectomy alone had no improvement in pain or neurologic function (one died in the immediate postoperative period), one of three patients with anterior fusions had some improvement (one died in the immediate postoperative period), and both of those patients with posterior fusions improved, although both died within a year of surgery from unrelated causes. CONCLUSIONS: Even though the osteopenia present in patients with chronic renal failure tends to allow wire pull-out and makes internal fixation of the spine difficult, successful cervical spinal fusion can relieve pain and improve neurologic deficits in selected patients with chronic renal failure and destructive spondyloarthropathy, allowing them to remain more active for longer periods of time.

Effect of calcitriol and pamidronate in multiple myeloma.

Addition of bisphosphonates to standard treatment of multiple myeloma (MM) decreases bone pain and skeletal events without influencing bone healing. Calcitriol, besides its established effects on bone remodeling and calcium metabolism, has both immunoregulatory and cell differentiating effects in vitro and in vivo. Moreover, low serum calcitriol has been reported in MM. We tested the effects of supportive treatment with calcitriol and pamidronate on bone disease in two stage-III-B MM patients with diffuse bone involvement, normal serum calcium, and low serum calcitriol. Complete blood counts, serum calcium, creatinine, quantitative serum and urine immunoglobulins, and biochemical indices of bone turnover, serum calcidiol, calcitriol, parathyroid hormone, skeletal radiographs, and bone mineral density by dual x-ray absorbtiometry were measured every 1-6 months for 16 months in the first patient and 7 months in the second patient. Both patients showed a dramatic improvement of MM activity and in bone disease documented by serial radiographs in the first patient and by increased bone mineral density (approximately 15%) in the second. The reduced serum calcitriol in both patients and the elevated parathyroid hormone observed in the first patient before treatment returned to normal. Supportive treatment with pamidronate does not induce bone healing in MM. Therefore, the results observed with the addition of calcitriol suggest that this hormone may have contributed to the apparent arrest of the progression of MM and caused stimulation of bone healing.

Spear tackler's spine. An entity precluding participation in tackle football and collision activities that expose the cervical spine to axial energy inputs.

We describe spear tackler's spine, a clinical entity that constitutes an absolute contraindication to participation in tackle football and other collision activities that expose the cervical spine to axial energy inputs. A subset of football players were identified who demonstrated: 1) developmental narrowing (stenosis) of the cervical canal; 2) persistent straightening or reversal of the normal cervical lordotic curve on erect lateral roentgenograms obtained in the neutral position; 3) concomitant preexisting posttraumatic roentgenographic abnormalities of the cervical spine; and 4) documentation of having employed spear tackling techniques. From data obtained by the National Football Head and Neck Injury Registry and the senior author's practice, 15 cases of spear tackler's spine were identified during 1987 to 1990. All 15 cases were evaluated because of complaints referable to the cervical spine or brachial plexus resulting from football injuries. Of these, 11 had complete neurologic recovery without permanent sequelae. Four cases resulted in permanent neurologic deficits: quadriplegia, 2; incomplete hemiplegia, 1; and residual long track signs, 1. Permanent neurologic injury occurred as the result of axial loading of a persistently straightened cervical spine from use of head-impact playing techniques. We suggest that individuals who possess the aforementioned characteristics of spear tackler's spine be precluded from participation in collision activities that expose the cervical spine to axial energy inputs.

Vertebral artery injury during anterior decompression of the cervical spine. A retrospective review of ten patients.

Ten patients who suffered iatrogenic injury to a vertebral artery during anterior cervical decompression were reviewed to assess the mechanisms of injury, their operative management, and the subsequent outcome. All had been undergoing a partial vertebral body resection for spondylitic radiculopathy or myelopathy (4), tumour (2), ossification of the posterior longitudinal ligament (1), nonunion of a fracture (2), or osteomyelitis (1). The use of an air drill had been responsible for most injuries. The final control of haemorrhage had been by tamponade (3), direct exposure and electrocoagulation (1), transosseous suture (2), open suture (1), or open placement of a haemostatic clip (3). Five patients had postoperative neurological deficits, but most of them resolved. We found direct arterial exposure and control to be safe, quick and reliable. Careful use of the air drill, particularly in pathologically weakened bone, as in infection or tumour, is essential. Arterial injury is best avoided by a thorough knowledge of the anatomical relationships of the artery, the spinal canal, and the vertebral body.