IN VITRO (EX VIVO) EXPANSION OF MURINE HEMATOPOIETIC STEM CELLS Running Title: In Vitro Expansion of Stem Cells

Currently there is significant interest in in vitro (ex vivo) expansion of human hematopoietic stem and progenitor cells in hematology and oncology. Transplantation of umbilical cord blood stem cells promises to be a new and exciting mode of bone marrow/stem cell transplantation since it is inexpensive and appears to be associated with milder graft vs. host disease (GVHD) than transplantation of adult cells. A potential problem of cord blood transplantation is the limited number of stem cells that may be harvested. The majority of cases of cord blood transplantation, therefore, have been attempted in children. If it were possible to expand the population of stem cells in umbilical cord blood and transplant them to adult recipients, it would significantly enlarge the scope of this form of transplantation. Already many preclinical studies have shown that it is possible to expand the population of total cells and progenitors in culture in the presence of combinations of cytokines. Whether or not it is possible to expand the population of hematopoietic stem cells which have long-term reconstitution capabilities remains to be clarified (1–3). The cytokines used in the majority of attempts of in vitro expansion were selected from a group of early-acting cytokines such as steel factor (SF, kit ligand), flt3 ligand (FL), interleukin (IL)-3, IL-6, IL-11, granulocyte/ macrophage-colony stimulating factor (GM-CSF), and granulocyte-CSF (G-CSF). The rationale for combining these cytokines has been explained in a recent review (4). Almost all protocols for in vitro expansion include IL-3 and many contain IL-1 because of their known myelopoietic effects.     

The gene for a recessively inherited human childhood progressive epilepsy with mental retardation maps to the distal short arm of chromosome 8.

A recently delineated childhood epilepsy has hitherto been observed only in a small geographic region in northern Finland, where, with the exception of one, both parents of all of the 11 sibships with affected individuals descend from one or two founding couples. The disease is characterized by generalized tonic-clonic seizures with onset at 5-10 years and progressive, severe mental retardation with onset 2-5 years after the first seizures. In this study the gene locus is assigned to the telomeric region of chromosome 8p by linkage. Analyses of recombinations place the locus in the 7-centimorgan interval between AFM185xb2 and D8S262 in which three markers, D8S504, D8S264, and AFM077yg5, show no recombinations with the phenotype. Haplotypes comprising alleles at the above five loci support the hypothesis of a single founding mutation for all affected chromosomes except the one belonging to the unrelated parent, who has a very different haplotype, suggesting another mutation or a very old ancestry of a single mutation. This study raises to three the number of heritable epilepsies whose gene loci have been mapped and provides a starting point for the cloning of the gene. It also suggests the possibility that the disease might not be limited to the northern Finnish population.     

Left and Right Coronary Artery Aneurysm Associated with Right Coronary Artery Occluding Thrombus: Demonstration by Transesophageal Echocardiography

This case provides a demonstration of the improved utility of transesophageal echocardiography, as compared to angiography and conventional echocardiography, in the setting of Kawasaki disease. Transesophageal echocardiography was able to demonstrate aneurysm and thrombolytic occlusion of the right coronary artery (RCA), whereas transthoracic echocardiography could not detect the occlusion and angiography missed the RCA findings altogether.     

The Effects of Dietary Boron on Bone Strength in Rats

Previous studies from our laboratory found that when boric acid(BA) was administered in the diet to rats, boron levels in bonewere approximately fourfold greater than serum levels. The currentstudies were undertaken to determine if these elevations producedadverse effects on several bone-related measures, includingserum electrolyte levels, bone structure, and bone strength.Data from two studies are presented: in the first study, youngadult male rats consumed a powdered diet containing 0, 3000,4500, 6000, or 9000 ppm BA for 9 weeks. Endpoints were serumcalcium, phosphorous, potassium, and chloride, as well as bloodand bone boron concentrations ([B]) measured weekly during the9-week exposure period, and at 8, 16, 24, and 32 weeks afterthe end of exposure. In the second study, the male and femaleyoung adult rats diet contained 0, 200, 1000, 3000, or 9000ppm BA for 12 weeks; endpoints measured weekly were serum levelsof calcium, phosphorous, and magnesium, bone [B], and bone structure(humerus) and strength (tibia, femur, and lumbar vertebrae).In treated rats, calcium was reduced in the first study butnot the second. Serum phosphorous was reduced in both studies;potassium was unchanged, chloride was increased by 1%, and magnesiumwas reduced in all BA-exposed groups in the second study, toa maximal 19% reduction. Bone [B] was consistently increasedin all treated groups, to concentrations approximately fourfoldthose of serum. After cessation of exposure, serum and urinaryboron concentrations dropped to within control values withina week. However, even 32 weeks after the end of exposure, bone[B] remained threefold greater than controls. Male tibia andfemur resistance to bending was unchanged. However, vertebralstrength in compression was significantly increased by 5–10%in all dose groups (200 to 9000 ppm). The pattern was substantiallysimilar in females. Only the humerus was examined by light microscopyand was found to be unchanged at any level of BA consumption.These data show that, despite a reduction in some serum electrolytelevels, BA consumption increased vertebral resistance to crushforce, without detectably altering the microscopic structureof the humerus or the resistance of femur and tibia to a bendingload. This increase in compression resistance occurred at exposurelevels substantially below those that were previously reportedto be reproductively toxic.     

Intracerebral arteriovenous malformations: evaluation with selective MR angiography and venography

Magnetic resonance (MR) angiography and spin-echo methods were used to evaluate intracerebral arteriovenous malformations (AVMs) in 10 patients. Spin-echo images obtained with flow presaturation demonstrated the nidus of the AVM in all cases, but it was difficult to determine feeding vessels. These vessels were directly visualized with three-dimensional MR angiography; their presence could be indirectly determined by means of selective presaturation of individual vessels, which resulted in a marked decrease in signal within the portion of the AVM supplied by that vessel. Vascular supplies from the internal carotid artery and anterior, middle, or posterior cerebral arteries were detected in all cases, but in three large malformations it was not possible to demonstrate small feeding vessels. MR angiograms were also helpful for further defining the nidus. The combination of MR angiographic and spin-echo methods provides information useful for therapeutic planning not provided by either technique alone.     

Increased wall tension in response to vasoconstrictors in isolated mesenteric arterial rings from patients with high blood pressure

Essential hypertension is associated with several alterations in arterial function. A wealth of information from animal models is available concerning hypertensive changes in the mesenteric circulation, while only few studies have examined human mesenteric arterial function. The tone of isolated mesenteric arterial segments (outer diameter 0.7-0.9 mm) was examined from individuals with high (n=17) or normal (n=22) blood pressure, grouped using the current definition of elevated blood pressure (140/90 mmHg). Since the majority of them were operated because of malignancies, we evaluated whether functional vascular properties provided information about patient prognosis. Wall tension development (mN/mm) in response to vasoconstrictors (noradrenaline, 5-hydroxy tryptamine, potassium chloride) was higher in mesenteric arterial rings from patients with high than normal blood pressure. There was no difference in vasoconstrictor sensitivity, or endothelium-dependent and endothelium-independent vasorelaxation. Arterial segment weight was higher in hypertensive subjects, suggesting vascular wall hypertrophy. The 10-year follow-up showed no differences in the control of arterial tone between the surviving (n=14) or deceased (n=25) patients. In conclusion, isolated mesenteric arterial segments from hypertensive patients showed increased wall tension in response to vasoconstrictors. Since the mesenteric circulation is an important regulator of peripheral arterial resistance, possible functional alterations in this vascular bed should be further investigated in hypertensive patients.     

Influence of microgravity on astronauts' sympathetic and vagal responses to Valsalva's manoeuvre

When astronauts return to Earth and stand, their heart rates may speed inordinately, their blood pressures may fall, and some may experience frank syncope. We studied brief autonomic and haemodynamic transients provoked by graded Valsalva manoeuvres in astronauts on Earth and in space, and tested the hypothesis that exposure to microgravity impairs sympathetic as well as vagal baroreflex responses. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in four healthy male astronauts (aged 38–44 years) before, during and after the 16 day Neurolab space shuttle mission. Astronauts performed two 15 s Valsalva manoeuvres at each pressure, 15 and 30 mmHg, in random order. Although no astronaut experienced presyncope after the mission, microgravity provoked major changes. For example, the average systolic pressure reduction during 30 mmHg straining was 27 mmHg pre-flight and 49 mmHg in flight. Increases in muscle sympathetic nerve activity during straining were also much greater in space than on Earth. For example, mean normalized sympathetic activity increased 445 % during 30 mmHg straining on earth and 792 % in space. However, sympathetic baroreflex gain, taken as the integrated sympathetic response divided by the maximum diastolic pressure reduction during straining, was the same in space and on Earth. In contrast, vagal baroreflex gain, particularly during arterial pressure reductions, was diminished in space. This and earlier research suggest that exposure of healthy humans to microgravity augments arterial pressure and sympathetic responses to Valsalva straining and differentially reduces vagal, but not sympathetic baroreflex gain.     

A 3‐year prospective radiographic evaluation of marginal bone level around different implant systems

Summary The aim of this study was to evaluate the change of marginal bone level radiographically around three different implant systems after 3 years in function. Fifty‐four patients were included and randomly assigned to three treatment groups of rough‐surface implants (TiUnite, n = 37), hybrid of smooth and rough‐surface implants (Restore, n = 38) and rough surface with microthread implants (Hexplant, n = 45). Clinical and radiographic examinations were conducted at the time of implant loading (baseline), 1 and 3 years after loading. A three‐level mixed‐effect analysis of covariance (ancova ) was used to test the significance of the mean marginal bone change of the three implant groups. A total 120 of 135 implants completed the study. None of the implants failed to integrate. Significant differences were noted in the marginal bone loss recorded for the three groups (P < 0·0001). At 3 years, the rough surface with microthread implants had a mean crestal bone loss of 0·59 ± 0·30 mm; the rough‐surface implants, 0·95 ± 0·27 mm; and the hybrid surface implants, 1·05 ± 0·34 mm. Within the limitations of this study, rough‐surface implants with microthread at the coronal part might have a long‐term positive effect in maintaining the marginal bone level against functional loading in comparison with implants without these two features.