The use of unfixed cryostat sections for electron microscopic study of D-amino acid oxidase activity in rat liver

Unfixed cryostat sections of rat liver were incubated to demonstrate D-amino acid oxidase activity at the ultrastructural level. Incubation was performed by mounting the sections on a semipermeable membrane which was stretched over a gelled incubation medium containing D-proline as substrate and cerium ions as capture reagent for hydrogen peroxide. After an incubation period of 30 min, ultrastructural morphology was retained to such an extent that the final reaction product could be localized in peroxisomes, whereas the crystalline core remained unstained. Control incubations were performed in the absence of substrate; the lack of final reaction product in peroxisomes indicated the specificity of the reaction. We conclude that the semipermeable membrane technique opens new perspectives for localization of enzyme activities at the ultrastructural level without prior tissue fixation, thus enabling localization of the activity of soluble and/or labile enzymes.

Blast exposure causes dynamic microglial/macrophage responses and microdomains of brain microvessel dysfunction

Exposure to blast overpressure (BOP) is associated with behavioral, cognitive, and neuroimaging abnormalities. We investigated the dynamic responses of cortical vasculature and its relation to microglia/macrophage activation in mice using intravital two-photon microscopy following mild blast exposure. We found that blast caused vascular dysfunction evidenced by microdomains of aberrant vascular permeability. Microglial/macrophage activation was specifically associated with these restricted microdomains, as evidenced by rapid microglial process retraction, increased ameboid morphology, and escape of blood-borne Q-dot tracers that were internalized in microglial/macrophage cell bodies and phagosome-like compartments. Microdomains of cortical vascular disruption and microglial/macrophage activation were also associated with aberrant tight junction morphology that was more prominent after repetitive (3×) blast exposure. Repetitive, but not single, BOPs also caused TNFα elevation two weeks post-blast. In addition, following a single BOP we found that aberrantly phosphorylated tau rapidly accumulated in perivascular domains, but cleared within four hours, suggesting it was removed from the perivascular area, degraded, and/or dephosphorylated. Taken together these findings argue that mild blast exposure causes an evolving CNS insult that is initiated by discrete disturbances of vascular function, thereby setting the stage for more protracted and more widespread neuroinflammatory responses.

DNA barcoding highlights a cryptic species of grenadier Macrourus in the Southern Ocean

Although three species of the genus Macrourus are recognized in the Southern Ocean, DNA sequencing of the mitochondrial COI gene revealed four well-supported clades. These barcode data suggest the presence of an undescribed species, a conclusion supported by meristic and morphometric examination of specimens.

Plasmodium falciparum possesses organelle-specific α-keto acid dehydrogenase complexes and lipoylation pathways

The human malaria parasite Plasmodium falciparum possesses a single mitochondrion and a plastid-like organelle called the apicoplast. Both organelles contain members of the KADH (alpha-keto acid dehydrogenase) complexes--multienzyme complexes that are involved in intermediate metabolism. In the asexual blood stage forms of the parasites, the alpha-ketoglutarate dehydrogenase and branched chain KADH complexes are both located in the mitochondrion, whereas the pyruvate dehydrogenase is exclusively found in the apicoplast. In agreement with this distribution, Plasmodium parasites have two separate and organelle-specific pathways that guarantee lipoylation of the KADH complexes in both organelles. A biosynthetic pathway comprised of lipoic acid synthase and lipoyl (octanoyl)-ACP:protein Nepsilon-lipoyltransferase B is present in the apicoplast, whereas the mitochondrion is supplied with exogenous lipoic acid, and ligation of the metabolite to the KADH complexes is accomplished by a lipoate protein ligase A similar to that of bacteria and plants. Both pathways are excellent potential targets for the design of new antimalarial drugs.

Exhibits facilitate histology laboratory instruction: student evaluation of learning resources

Some professional schools have replaced microscopes for histology laboratory instruction with printed and electronic media. It is recognized that these media cannot replace experience with the microscope and that there is a cognitive dissonance of completely replacing microscope study. In addition, students believe that their time is not optimally used in the traditional histology laboratory. Therefore, at Loma Linda University, nine weekly microscope exhibits consisting of 10-15 slides each were prepared. For each exhibited slide, a one page "atlas" is provided, consisting of labeled low- and high-power color micrographs taken from that slide and an informative legend. By referring to the atlas, the student can easily identify the exact field and the labeled features with little help from an instructor. A live or taped video demonstration of the microscope exhibit is available on the first day of the exhibit. During the eighth week of the quarter, students were asked to evaluate the various learning resources available to them. No resource was valued significantly more than the microscope exhibits, but the video demonstrations were valued significantly more than the printed black and white atlas or the color atlas on CD. These exhibits have been used for 2 years to instruct a class of 90 dental students. Advantages are (1) students' time is used efficiently, (2) only one slide set and a fourth as many microscopes need be maintained compared with a traditional laboratory, and (3) one-of-a-kind slides derived from research activities provide for high impact learning.

Angiogenesis after stroke is correlated with increased numbers of macrophages: the clean-up hypothesis

Brain cells manufacture and secrete angiogenic peptides after focal cerebral ischemia, but the purpose of this angiogenic response is unknown. Because the maximum possible regional cerebral blood flow is determined by the quantity of microvessels in each unit volume, it is possible that angiogenic peptides are secreted to generate new collateral channels; other possibilities include neuroprotection, recovery/regeneration, and removal of necrotic debris. If the brain attempts to create new collaterals, microvessel density should increase significantly after ischemia. Conversely, if angiogenic-signaling molecules serve some other purpose, microvessel densities may increase slightly or not at all. To clarify, the authors measured microvessel densities with quantitative morphometry. Left middle cerebral arteries of adult male Sprague-Dawley rats were occluded with intraluminal nylon suture for 4 hours followed by 7, 14, 19, or 30 days of reperfusion. Controls received no surgery or suture occlusion. Changes in microvessel density and macrophage numbers were measured by light microscopic morphometry using semiautomated stereologic methods. Microvessel density increased only in the ischemic margin adjacent to areas of pannecrosis and was always associated with increased numbers of macrophages. Ischemic brain areas without macrophages displayed no vascularity changes compared with normal animals. These data suggest that ischemia-induced microvessels are formed to facilitate macrophage infiltration and removal of necrotic brain.

A simple stereologic method for analysis of cerebral cortical microvessels using image analysis

Previous methods for determining morphological features of vascular networks in cerebral cortex were subject to arbitrary variation and bias. Unbiased estimates of vessel number, volume, surface area and length can be obtained using stereology but these techniques tend to be tedious and time-consuming. Stereologic protocols generally require micrographs that have to be analyzed manually for intersections of vessels on grid points or lines. In this report, we provide a simpler and more precise method for measuring morphological features of cerebral cortical microvessels. Images of microvessels in 1 microm toluidine blue stained sections were captured using a popular image analysis software package. Luminal surfaces of endothelial cells were automatically traced using commonly available features; the two-dimensional data of vessels (diameter, area, perimeter and number of vessels) were automatically computed and transferred to a spreadsheet. Three-dimensional features were then determined using basic stereologic equations. The method eliminates the need for manual measurements and is particularly time- and cost-effective for quantitative studies where numerous images have to be evaluated.

Dose response of rat retinal microvessels to proton dose schedules used clinically: a pilot study

PURPOSE

This preclinical rat pilot study quantifies retinal microvessel, endothelial, and pericyte population changes produced by proton irradiation

METHODS AND MATERIALS

The left eyes of rats were irradiated with single doses of 8, 14, 20, and 28 Gy protons; right eyes, with two fractions. Animals were euthanized, and eyes were removed; elastase digests were prepared, and cell populations were counted in sample fields. Results were compared with unirradiated controls.

RESULTS

Progressive time- and dose-dependent endothelial cell loss occurred following all schedules. Cell loss was significantly different from control values (p < 0.001) following 28 Gy and following 20 Gy (p < 0.05) in a single dose. Endothelial cell loss was the same for single- and split-dose schedules. Progressive endothelial cell loss produced vessel collapse and acellular vessel strands. Endothelial cells were in the G(0) phase of the mitotic cycle. 28 Gy produced photoreceptor cell loss.

CONCLUSION

The retinal digest is an elegant bioassay to quantify the microvessel population response. Single- and split-dose schedules appear to yield similar outcomes, in terms of endothelial cell density.

Variables that influence the relationship between osseointegration and bone adjacent to an implant

It is often assumed that there is a direct relationship between the bone density adjacent to an implant, as revealed by radiographs, and the percent histologic osseointegration. Moreover, the lack of standardized methods for evaluation of histologic preparations makes it difficult to compare published studies, especially as little is known about the variables that influence these measurements. In this animal study, computer-assisted lineal analysis was used to evaluate the effects of subject, tooth position, and implant surface site on measured bone density and osseointegration in a bone augmentation experiment. Three sites--coronal lingual, apical lingual, and apical facial--were analyzed around each of 6 (3.75 x 8 mm) threaded machined titanium implants, as well as the apical facial site of 21 other implants placed in the mandibular premolar area of 5 dogs. In all sites, a progressive decrease in bone density was observed from bone adjacent to the implant to that at the titanium implant surface. There was an animal effect on osseointegration, but there were no differences between the mandibular premolar locations (second, third, and fourth). Most importantly, there were significant measurable effects attributable to the surface site examined. The need for carefully standardized histologic evaluations is established.

Luminal localization of blood-brain barrier sodium, potassium adenosine triphosphatase is dependent on fixation

Cytochemical data in the literature reporting localization of sodium, potassium adenosine triphosphatase (Na(+), K(+)-ATPase) in the blood-brain barrier (BBB) have been contradictory. Whereas some studies showed the enzyme to be located exclusively on the abluminal endothelial plasma membrane, others demonstrated it on both the luminal and abluminal membranes. The influence of fixation on localization of the enzyme was not considered a critical factor, but our preliminary studies showed data to the contrary. We therefore quantitatively investigated the effect of commonly used fixatives on the localization pattern of the enzyme in adult rat cerebral microvessels. Fixation with 1%, 2%, and 4% formaldehyde allowed deposition of reaction product on both the luminal and abluminal plasma membranes. The luminal reaction was reduced with increasing concentration of formaldehyde. Glutaraldehyde at 0.1%, 0.25%, 0.5%, in combination with 2% formaldehyde, drastically inhibited the luminal reaction. The abluminal reaction was not significantly altered in all groups. These results show that luminal localization of BBB Na(+), K(+)-ATPase is strongly dependent on fixation. The lack of luminal localization, as reported in the literature, may have been the result of fixation. The currently accepted abluminal polarity of the enzyme should be viewed with caution.

Specific downregulation of presenilin 2 gene expression is prominent during early stages of sporadic late-onset Alzheimer's disease

Mutations in the presenilin genes PS1 and PS2 cause familial Alzheimer's disease (AD). In a previous study, we reported that PS2 mRNA levels are decreased in the hippocampus, frontal cortex and basal forebrain of subjects with late-onset sporadic AD. In this study, we examined whether this downregulation occurs as the disease progresses from mild to severe stages or whether downregulation of PS2 expression is an early event in AD. We used in situ hybridization histochemistry to quantify the level of expression of PS2 message in the hippocampus of normal subjects and subjects with mild, moderate or severe AD. Several regions of the hippocampus which are sequentially susceptible to AD neuropathology as the disease progresses in severity were analyzed. We demonstrate that specific downregulation of PS2 expression is as severe in subjects with mild AD as it is in subjects in late stages of the disease. In addition, we show that hippocampal regions that are relatively free of AD neuropathology during early stages of the disease exhibit severely compromised PS2 mRNA levels even in mild AD cases. In contrast, PS2 is expressed at normal levels in the cerebellum, a region which succumbs to significantly fewer AD-related insults even at very advanced stages of the disease. These results suggest that the specific downregulation of PS2 gene expression is an early event in sporadic late-onset AD.

Calcium-dependent ATPase unlike ecto-ATPase is located primarily on the luminal surface of brain endothelial cells

Numerous cytochemical studies have reported that calcium-activated adenosine triphosphatase (Ca2+-ATPase) is localized on the abluminal plasma membrane of mature brain endothelial cells. Since the effects of fixation and co-localization of ecto-ATPase have never been properly addressed, we investigated the influence of these parameters on Ca2+-ATPase localization in rat cerebral microvessel endothelium. Formaldehyde at 2% resulted in only abluminal staining while both luminal and abluminal surfaces were equally stained following 4% formaldehyde. Fixation with 2% formaldehyde plus 0.25% glutaraldehyde revealed more abluminal staining than luminal while 2% formaldehyde plus 0.5% glutaraldehyde produced vessels with staining similar to 4% and 2% formaldehyde plus 0.25% glutaraldehyde. The abluminal reaction appeared unaltered when ATP was replaced by GTP, CTP, UTP, ADP or when Ca2+ was replaced by Mg2+ or Mn2+ or p-chloromercuribenzoate included as inhibitor. But the luminal reaction was diminished. Contrary to previous reports, our results showed that Ca2+-specific ATPase is located more on the luminal surface while the abluminal reaction is primarily due to ecto-ATPase. The strong Ca2+-specific-ATPase luminal localization explains the stable Ca2+ gradient between blood and brain, and is not necessarily indicative of immature or pathological vessels as interpreted in the past.

Distribution and activation of uterine mononuclear phagocytes in peripartum endometrium and myometrium of the mouse

The present study tested the hypothesis that macrophage distribution and activation are enhanced in the uterus before term. Mid-uterine horn tissue strips from mice on Days 15 and 18 of pregnancy, the day of birth (= Day 19), and one day postpartum were paraffin-embedded and then sectioned, stained with a monoclonal pan-macrophage marker (BM8), and processed for visualization and quantification of resident macrophages per nuclear area. Macrophages were dispersed throughout the endometrium and subluminal epithelium; cell numbers declined on the day before term, then increased postpartum. Within myometrium, macrophages congregated in stroma surrounding muscle bundles, and staining was enhanced near term. Macrophage numbers were similar in pregnant and postpartum uteri, enhanced more than 2-fold over those in nonpregnant controls. Uterine sections were also analyzed by laser-scanning cytometry to enumerate activated macrophages (i.e., those that express the intercellular adhesion molecule marker CD54+) and to determine cell cycle (propidium iodide fluorescence). Activated macrophages were directly proportional to cell numbers and, by cell cycle analysis, were not terminally differentiated. Highest cell numbers occurred on Day 15: 4-fold greater than those in nonpregnant controls and 2-fold higher than those at Day 18 or in postpartum groups. These findings indicate a decline in endometrial macrophage numbers at least one day before the onset of parturition and raise the possibility that trafficking of this immune cell may contribute to onset of labor.

From sequence to chromosome: the tip of the X chromosome of D. melanogaster

One of the rewards of having a Drosophila melanogaster whole-genome sequence will be the potential to understand the molecular bases for structural features of chromosomes that have been a long-standing puzzle. Analysis of 2.6 megabases of sequence from the tip of the X chromosome of Drosophila identifies 273 genes. Cloned DNAs from the characteristic bulbous structure at the tip of the X chromosome in the region of the broad complex display an unusual pattern of in situ hybridization. Sequence analysis revealed that this region comprises 154 kilobases of DNA flanked by 1.2-kilobases of inverted repeats, each composed of a 350-base pair satellite related element. Thus, some aspects of chromosome structure appear to be revealed directly within the DNA sequence itself.

Quantitative electron microscopic study of the hypoxic fetal sheep heart

In order to determine the effects of chronic, high-altitude hypoxia on the ovine fetal heart, we exposed pregnant ewes to 3,820 m beginning at 30 days gestation. We previously showed that following approximately 110 days of hypoxia the fetal heart showed significant reduction in cardiac output (76% of control) and contractility, and elevated levels of citrate synthase and lactate dehydrogenase. To investigate ultrastructural influences on these observed physiologic changes at altitude, we hypothesized that the volume densities of myofibrils and mitochondria, and glycogen content would be reduced in the ovine fetal heart and that this may contribute to contraction and cardiac output deficits in hypoxia. Mitochondria and myofibril volume density were determined by standard point-counting techniques and glycogen content was determined by biochemical analysis. The glycogen content from the hypoxic right ventricle (4.8 +/- 0.3%) was significantly lower than in control right ventricle (6.8 +/- 0.5%) and both left ventricles (hypoxia, 7.2 +/- 0.5; control, 7.8 +/- 0. 4%). Total mitochondrial volume density was also significantly reduced following hypoxia (15.5 +/- 0.7%) compared to controls (16.9 +/- 0.4%). As is common in the ovine fetal heart, the myofibril volume density of the right ventricle from both groups was significantly higher than the left ventricle (RV, 58.6 +/- 1.6; LV 54.3 +/- 0.9%). However, it was not different between control and high altitude. In support of our hypothesis, we may speculate that deficits in the quantity of myocyte glycogen and mitochondria contribute to the observed reduction in cardiac output and contractility, despite the upregulation of citrate synthase and lactate dehydrogenase. In contrast, myofibril volume density was unchanged.

Evaluation of bone-implant integration: efficiency and precision of 3 methods

Computer-assisted planimetry, computer-assisted lineal analysis, and point-counting stereology have been compared with respect to their reproducibility and the time required to analyze bone-implant integration. Sections of 6 threaded dental implants selected from a bone augmentation experiment for their wide range of new bone formation were analyzed by each method 3 times. The bone density and percentage of osseous integration were evaluated at 4 sites around each implant section. It was found that computer-assisted planimetry demonstrated a modest but significantly greater variance (P < .05) in bone density estimates when compared to the computer-assisted lineal analysis and point-counting methods. Computer-assisted planimetry requires a different method of measuring each parameter and separate fields of view to evaluate fields distant from the implant. However, this can all be accomplished with line probes, as in computer-assisted lineal analysis, which extend from the implant surface into the surrounding alveolar bone. Whereas computer-assisted planimetry requires a separate identification of the perimeter of each field to be analyzed (next to and distant from the implant), computer-assisted lineal analysis allows expansion of the field to be evaluated without creating a new field of view. Also, following a limited learning curve, both point-counting and computer-assisted lineal analysis required less time to complete than did computer-assisted planimetry.

Effects of long-term, high-altitude hypoxia on the capillarity of the ovine fetal heart

To determine the effect of chronic hypoxia on myocardial capillarity, we exposed pregnant ewes to an altitude of 3,820 m from day 30 to day 139 of gestation and compared the fetus to low-altitude (approximately 300 m) controls. We hypothesized that capillarity would increase in the hypoxic myocardium to optimize oxygen and metabolite flux to hypoxic tissues. Fetal hearts were fixed by retrograde aortic perfusion and processed for microscopy and stereological evaluation. Fiber cross-sectional area and capillary density were measured and standardized to sarcomere length. Capillary volume density and capillary diameter were measured, capillary-to-fiber ratio and capillary length density were calculated, and the capillary anisotropy coefficient was obtained from a table of known values. Capillary-to-fiber ratio, capillary volume density, and the capillary anisotropy coefficient were not different between hypoxia and control groups. Capillary diameter was significantly larger in the right compared with the left ventricle of hypoxic but not control hearts; fiber cross-sectional area tended to be larger in the right ventricle of both groups, but this was not significant. As a result of larger fiber size, capillary density and capillary length density were significantly smaller in the right ventricle of hypoxic but not control fetal hearts. Contrary to our hypothesis, the ovine fetus does not show morphological adaptation in the myocardium after approximately 109 days of high-altitude hypoxic stress.

Development of periradicular lesions in immunosuppressed rats

PROBLEM

The role of bacteria has been well established in pulpal and periapical diseases, but the contribution of the host defenses is less clear.

OBJECTIVES

The purpose of this study was to compare periradicular lesion development in immunosuppressed rats with that in normal rats.

STUDY DESIGN

Fifteen rats were given weekly injections of Cytoxan (Bristol Laboratories) to suppress their immune systems. The pulps of mandibular first molars of these animals and another 15 rats that had received no medications were exposed and left open to their oral flora. The rats were killed at 2, 4, and 6 weeks. Radiographic analysis was performed by means of a computer linked to a digitizing board and stylus. In addition, specimens were decalcified, sectioned, stained, and examined under a microscope with a grid to quantify relative percentages of surface areas of bone, root, periodontal ligament, marrow spaces, soft tissue, and inflammatory infiltrate.

RESULTS

Statistical analysis showed a significantly greater radiographic bone loss in the immunosuppressed group only at 4 weeks. No significant histologic differences were found between the two groups.

CONCLUSION

Our results suggest that reduction of circulating leukocytes may not significantly affect the development of periradicular pathosis in rats.

Effects of estrogen replacement on choline acetyltransferase and trkA mRNA expression in the basal forebrain of aged rats

The effects of one week of estrogen replacement on choline acetyltransferase (ChAT) and trkA mRNA expression are examined in young and aged rodents to determine whether estrogen continues to affect cholinergic neurons in aging brain. Significant increases in ChAT and trkA are observed in the nucleus basalis of Meynert (nBM) of both age groups. ChAT expression is also increased in the HDB without changes in trkA expression. Results indicate modulation of ChAT expression by estrogen is retained in the aged rodent brain and suggests the possibility that changes in ChAT expression may be dissociated from concurrent alterations in trkA.

Neuronal expression of STM2 mRNA in human brain is reduced in Alzheimer's disease

Mutations in the STM2 gene cause familial Alzheimer's disease (AD) in Volga Germans. To understand the function of this protein and how mutations lead to AD, it is important to determine which cell types in the brain express this gene. In situ hybridization histochemistry indicates that STM2 expression in the human brain is widespread and is primarily neuronal. In addition, STM2 mRNA is expressed in a cell line with neuronal origins. Quantification of the level of expression of the STM2 message in the basal forebrain, frontal cortex, and hippocampus reveals a significant decrease in AD-affected subjects compared to normal age-matched controls. These data suggest that downregulation of neuronal STM2 gene expression may be involved in the progression of AD.

The effects of ovariectomy and estrogen replacement on trkA and choline acetyltransferase mRNA expression in the basal forebrain of the adult female Sprague-Dawley rat

Cognitive deficits associated with aging and with neurodegenerative diseases such as Alzheimer's disease have been attributed to degeneration of cholinergic neurons in the basal forebrain. Estrogen is known to provide trophic support to cholinergic neurons, although the mechanisms underlying the actions of estrogen have yet to be determined. Because cholinergic neurons require neurotrophic growth factors for their survival, it is possible that the trophic effects of estrogen on basal forebrain systems are caused by enhanced expression of neurotrophins or their receptors. To begin to examine this hypothesis, we used in situ hybridization analysis to determine the effects of ovariectomy (ovx) and estrogen replacement on trkA mRNA levels in the rat basal forebrain. Ten days of estrogen deprivation after ovx resulted in significant decreases in trkA mRNA levels in the horizontal limb of the diagonal band of Broca and the nucleus basalis of Meynert. Short-term estrogen replacement therapy restored trkA mRNA expression to a level comparable with ovary-intact animals. No changes in trkA mRNA levels were observed in the vertical limb of the diagonal band of Broca after ovx or estrogen replacement. To assess the functional status of cholinergic neurons in the absence and presence of estrogen, the effects of ovx and estrogen replacement on ChAT mRNA levels were also examined and found to reflect the changes observed in trkA mRNA expression. These studies suggest that the trophic effects of estrogen on basal forebrain cholinergic systems may be mediated, in part, through the signaling of neurotrophic growth factors through their receptors.

Evidence for the requirement of protein synthesis and protein kinase activity in the temperature regulated stability of a Tetrahymena surface protein mRNA

In Tetrahymena thermophila, the expression of the temperature-specific surface protein SerH3 is controlled primarily by a temperature-dependent change in the stability of its mRNA. The change in SerH3 mRNA stability occurs very rapidly after a shift in incubation temperature. This change in temperature could affect SerH3 mRNA stability directly by producing structural changes in the mRNA or regulatory factors acting on SerH3 mRNA. Alternatively, the temperature change could act indirectly through a signal transduction pathway leading to de novo synthesis of new regulatory factors or modifications of existing regulatory factors. To address these issues, we monitored the effect of temperature on an in vitro SerH3 mRNA decay assay and the in vivo effects of a variety of inhibitors against protein synthesis and protein kinases on SerH3 mRNA stability. The results of Northern analysis of SerH3 mRNAs in an in vitro mRNA decay assay indicate that temperature alone can not change the half-life of this mRNA. Furthermore, slot blot analysis of cytoplasmic RNAs show that protein synthesis and the action of protein kinases are not required for SerH3 mRNA turnover in cells grown at 30 degrees C. In contrast, our results indicate that the rapid decay of the SerH3 mRNA in cells grown at 30 degrees C and shifted to 40 degrees C requires a one time serine/threonine phosphorylation event which occurs at the temperature shift. In addition, the data show that a regulatory protein involved in rapid SerH3 mRNA decay must be newly and continuously synthesized following the temperature shift from 30 to 40 degrees C. These data show the complexity of temperature regulated mRNA decay and indicate that phosphorylation and protein synthesis are major factors in this process.

Pilot study of monoclonal antibody localization in subcutaneous and intracranial lung tumor xenografts after proton irradiation

The purpose of this study was to determine if proton irradiation can increase the localization of radiolabeled monoclonal antibodies (MAb) in subcutaneous (s.c.) or intracranial (i.c.) human lung tumors xenotransplanted in athymic rats. Rats with carcinoembryonic antigen (CEA)-expressing (NCI-H441) tumors were irradiated using 3 different proton time-dose regimens, followed by 111In-ZCE025, an anti-CEA MAb, which was injected 2 hr after the last dose of irradiation, and the animals were euthanized 3 days later for biodistribution and other assays. Proton irradiation at 10 gray (Gy) as a single dose or in 2 Gy fractions given on 5 consecutive days increased the uptake of 111In-ZCE025 into s.c. tumors by 292% and 182%, respectively, compared to nonirradiated controls. No enhancement in radiolabeled MAb delivery was seen after hemibrain irradiation in animals with i.c. tumors. Histopathological examination of both implantation sites showed a viable poorly differentiated adenocarcinoma with a decrease in blood vessel density, a decrease in mitotic activity, and an increase in areas of necrosis following irradiation as compared with adjacent nonirradiated tissue. CEA expression was generally maintained in vivo in that the marker was detectable in the tumor, plasma, and cerebrospinal fluid. Oxygen radical production by peripheral blood cells from s.c. and i.c. tumor-bearing rats exhibited strikingly different patterns of responsiveness. I.c. injected animals were 24% lighter than their s.c. injected counterparts, but no neurological signs of tumor progression were noted. The results indicate that proton irradiation can be used effectively to increase the delivery of radiolabeled MAb to s.c. implanted human lung tumor xenografts. However, in order to accomplish this in the brain, other radiation time-dose schedules and treatments may be needed.

The effect of storage time on the degree of dye leakage of root-end filling materials

The quality of the apical seal obtained by root-end filling materials generally has been assessed by the extent of dye penetration. Most investigators have allowed the root-end filling materials to set before they are tested. The purpose of this study was to evaluate if storage time had any influence on the amount of dye leakage. Seventy extracted single rooted human anterior teeth were used. After removal of their anatomical crowns, the roots were instrumented, filled with gutta-percha and Roth's sealer, and subjected to test conditions. The roots were coated with two coats of nail polish. Root ends were resected and class I cavities prepared. Sixty class I root-end cavities were filled with with either amalgam, super EBA, or IRM (20 each). Ten roots in each group were placed immediately into India ink for 48 h, the other 10 were stored for 24 h before placement into the ink. Ten roots (five per group) were used as positive (gutta-percha, no sealer) and negative (bone wax) controls. The roots were then demineralized, linear dye leakage was measured, and the data were evaluated statistically using ANOVA. Super EBA, and IRM showed significantly less dye leakage than amalgam (P < 0.0001). No significant difference existed between Super EBA and IRM. Storage time had no significant influence on the amount of dye leakage observed in this study.

Osteoclast recruitment and modulation by calcium deficiency, fasting, and calcium supplementation in the rat

In the rat, 1 week of a calcium-deficient diet will recruit large numbers of osteoclasts to long bone endosteal surfaces. Subsequent calcium supplementation causes the osteoclasts to disappear in 1-3 days but as little as 3 hours of calcium supplementation reduces the extent of their ruffled borders. To test the hypothesis that at some point there is an irreversible inhibition of osteoclasts, male, weanling, calcium-deficient, SD rats were given various amounts of calcium-containing diet followed by a 12-hour fast. No changes in seven morphological indices of osteoclast activity were found. The hypothesis that the fast had reversed the effects of the calcium diet was supported by a second experiment indicating that no inhibition threshold had been reached. Another experiment showed differences in the degree of osteoclast inhibition with different amounts of calcium supplementation, again without evidence of a threshold. These experiments raised two questions: (1) Will fasting recruit osteoclasts in calcium-replete rats? and (2) Is osteoclast recruitment facilitated by the presence of postosteoclasts? The results of experiments testing these hypotheses support the conclusion that fasting and calcium deficiency maintain plasma calcium levels by different mechanisms, and post-osteoclasts are not available for reactivation. It is concluded that inhibition of osteoclasts by dietary calcium is a graded phenomenon, and when osteoclasts have lost contact with the bone surface they are unavailable for reactivation; a threshold has been reached.

rseB, a chromosomal locus that affects the stability of a temperature-specific surface protein mRNA in Tetrahymena thermophila

In Tetrahymena thermophila, the expression of a temperature-specific surface protein known as SerH3 is primarily controlled by a temperature-dependent change in the stability of the mRNA that encodes this protein. At 30 degrees C the SerH3 mRNA displays a half-life of 60 minutes while at 40 degrees C the half-life decreases to only 3 minutes. We used a Tetrahymena mutant cell line (rseB) defective in expression of SerH3 at 30 degrees C to explore the mechanisms involved in temperature-dependent mRNA stability. The results of in vitro nuclear run-off assays and Northern and slot blot analysis of cytoplasmic and nuclear RNAs show that the rseB locus encodes a temperature-sensitive product that has no effect on SerH3 gene transcription or the steady-state levels of SerH3 nuclear RNA. However, the product of this locus does have a dramatic effect on cytoplasmic levels of the SerH3 mRNA at 30 degrees C, indicating that SerH3 gene expression is affected post-transcriptionally within the cytoplasm. To explore the possibility that the rseB locus controls SerH3 mRNA stability we developed an in vitro mRNA decay assay. This assay successfully duplicates the differential decay of the SerH3 mRNA observed in wild-type cells grown at different temperatures. The apparent half-life of the SerH3 mRNA in cytoplasmic extracts derived from cells grown at 30 degrees C is approximately 45 minutes while in cytoplasmic extracts derived from cells grown at 40 degrees C it is only 6 minutes. When similar experiments are performed using extracts prepared from the Tetrahymena rseB cell line, we find that the SerH3 mRNA is only stable in extract prepared from cells grown under conditions in which the mRNA accumulates to detectable levels in the cytoplasm. These results indicate that the product of the rseB locus is a trans-acting cytoplasmic factor that exerts its effect on SerH3 gene expression by regulating SerH3 mRNA stability.

Periodontal repair in dogs: expanded polytetrafluoroethylene barrier membranes support wound stabilization and enhance bone regeneration

A wound stabilizing effect of expanded polytetrafluoroethylene (ePTFE) membranes was evaluated in supra-alveolar periodontal defects in 5 beagle dogs. The defects, 5 to 6 mm in height, were surgically created around the 2nd, 3rd, and 4th mandibular premolar teeth in contralateral jaw quadrants. The root surfaces were conditioned with heparin, which, in this model, has been demonstrated to compromise periodontal healing and result in formation of a long junctional epithelium. Wound closure included application of ePTFE membranes around each premolar tooth in one jaw quadrant in each dog and flap positioning coronal to the cemento-enamel junction in both jaw quadrants. Healing progressed uneventfully except for 3 teeth in 2 dogs, which experienced membrane exposure. The dogs were sacrificed after a 4-week healing period and tissue blocks were prepared for histometric analysis. Connective tissue repair in heparin+membrane-treated teeth averaged 98% of the defect height compared to 84% in control heparin-treated teeth (P < or = 0.05). Junctional epithelium formation was smaller in membrane-treated teeth than in control teeth (P < or = 0.05) and was usually terminated coronal to the membrane. Bone regeneration was enhanced in membrane-treated teeth compared to controls (P < or = 0.01) and was strongly correlated to the area under the membrane in teeth without membrane exposure (r2 = 0.993; P = 0.002). This correlation was reduced when teeth with membrane exposure were included in the analysis (P < or = 0.05). Cementum regeneration was minimal under both treatment conditions. Root resorption was increased in membrane-treated compared to control teeth (P < or = 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

The value of repeated chest radiographs in the follow-up of patients with germ cell testicular tumours

Patients with germ cell testicular tumours customarily have repeated follow-up chest radiographs after treatment. This study assesses the contribution of chest radiography to the detection of recurrent disease in 162 patients. Six patients developed an intrathoracic recurrence, but in only one case was the chest radiography the only indication of recurrence. Five had other evidence to suggest recurrence, such as raised serum markers or palpable masses. The yield from follow-up chest radiographs in patients with germ cell testicular tumours is very low and their use must be balanced against both the harmful effects of radiation and the financial cost.

The measurement of the regression of carcinoma of the bladder using ultrasonography and CT scanning during and after radical radiotherapy

In 50 patients receiving radical radiotherapy for carcinoma of the bladder a well-defined tumour was observed in the bladder either by trans-abdominal ultrasonography or by CT scanning prior to treatment. The histological type was transitional cell carcinoma 46, adenocarcinoma 1 and squamous cell carcinoma 3. The cross-sectional area of the tumour in the transverse plane was measured before the start of radiotherapy. In 37 patients serial measurements were made by ultrasonography during and after radical radiotherapy. In three patients no regression was seen during the first 14-27 days of treatment. In 34 patients with transitional cell carcinoma the median area-halving time was 37 days. Serial measurements of the volume of the tumour before, during and after radiotherapy were made by CT scanning in 29 patients. In two patients the tumour progressed with a volume-doubling time of 93 and 108 days, respectively. In 25 patients with transitional cell carcinoma the median volume-halving time was 29 days with a median area-halving time of 44 days. Linear-regression analysis of the initial tumour areas (31 patients) as measured by ultrasonography and CT scanning was performed. The correlation coefficient was r = 0.69. The correlation coefficient for the area halving-times measured both by ultrasonography and CT scanning was r = 0.53 (nine patients). Biphasic regression with a second slower phase with area-halving and volume-halving times of several hundred days was observed in six patients. Calcification of the tumour during and after radiotherapy was observed in several patients. No significant change in the CT number of the tumour was observed after radiotherapy. The median initial tumour volume as measured by CT scanning was 38 (7-211) cm3. The median initial tumour area as measured by ultrasonography was 16 (6-40) cm2. A tumour of median size with a median halving-time would take 120 days (4 months) to regress completely. Cystoscopy within 6 months of the start of radiotherapy is unlikely to be of value because many bladder tumours are continuing to regress during this period of time. Progression of the tumour during or after radiotherapy can be detected either by CT scanning or ultrasonography.

Is percutaneous transluminal angioplasty better than exercise for claudication? Preliminary results from a prospective randomised trial

Percutaneous transluminal angioplasty (PTA) is a commonly performed procedure for the treatment of intermittent claudication despite the lack of controlled studies. The aim of this study was to compare PTA with supervised exercise therapy for patients with arterial occlusive disease judged suitable for PTA at angiography. Patients were assessed before treatment commenced and at three monthly intervals afterwards. Assessment included measurement of resting ankle brachial pressure indices (ABPI), and claudicating and maximum walking distances on a treadmill up a 10 degrees incline. Twenty patients were randomised to receive PTA and 16 exercise. The groups were similar in age, sex, smoking habits and arteriographic pattern of disease. In the PTA group two patients had angioplasties that were technically unsuccessful and two other patients subsequently required surgery. One patient in the exercise group subsequently had a PTA. After PTA, mean ABPI were significantly improved at 3, 6 and 9 months (P less than 0.01) without a corresponding significant increase in mean maximum walking distances. However in the exercise group despite no increase in mean ABPI, mean maximum walking distances increased progressively, with significant increases at 6, 9 and 12 months (P less than 0.01).

DataVoice: a microcomputer-based general purpose voice-controlled data-collection system

An integrated system of hardware and software has been developed to combine the input of coordinate data from a digitizing pad with voice input for object identification or classification. The menu and voice-controlled software generates a sequential ASCII file which contains an object identification section and a data section. Rules for data entry and analysis programs have been developed for several applications. These are being tested and include general stereological analyses, bone, kidney and skin histomorphometry, boundary analyses, neuron classification and malignancy grading.

Rapid changes of light microscopic indices of osteoclast-bone relationships correlated with electron microscopy

The relationships of tibial endosteal osteoclasts to bone surfaces were quantitatively evaluated during initiation of calcium repletion in calcium-deficient rats. To do this, indices of osteoclast-bone relationships obtained by light microscopy were devised and evaluated by comparing with those obtained by electron microscopy (EM). These indices are the percent of the osteoclast width that (1) exhibits markers indicative of a ruffled border, (2) is in close contact with bone, (3) is isolated from bone by other cell types, and (4) is separated from bone by intercellular material. The indices obtained by light microscopy were strongly correlated with similar indices obtained by EM and were equally sensitive but considerably easier to obtain. The ruffled border and contact index were significantly decreased by 3 hours after beginning the meal whereas cells of other types became interposed between the osteoclasts and the bone.

A review of experimental methods measuring peripheral nerve regeneration in animals

We have reviewed the morphologic, electrophysiologic, biochemical, and functional methods of evaluating PN regeneration in animal models. There are a large number of anatomic techniques that can provide clear insights into the processes of peripheral nerve regeneration. Since many of these are costly in terms of labor, careful selection of the technique appropriate for the question asked is important. Two of the more important questions are: 1) What are the neurotrophic factors produced by the distal segment that attract the growing axon tip? and 2) What are the components of the basal lamina that facilitate the directed growth of the axons? To answer these questions, whole mount preparations provide the means to economically evaluate the result of experimental manipulation of the environment. Automated nerve fiber counts will be increasingly used to help interpret electrophysiologic studies. Quantitative as well as descriptive ultrastructural analyses will continue to provide valuable data that will be needed in the interpretation of biochemical and histochemical studies. Immunohistochemical probes are sure to become more important as the range of their specificities broadens. With the diversity of anatomic methods available and their capacity to help us visualize the processes occurring during nerve regeneration they will remain a key tool in these studies. Electrophysiologic methods that integrate the CAP and correlate it with the number of functioning NF are most useful. Functional methods are beginning to become more objective and quantitative. The most precise measurements are muscle weight and the isometric response of muscle to tetanic contraction. Sensory function has now been measured objectively by Horch. Single methods of measuring PN regeneration give only limited data, but by combining methods a better understanding of PN regeneration is possible. While understanding the limitations of each method and technique, multi-parameter animal models may provide data most helpful clinically. However, because of great species variability in the reparative response, caution must be given not to extrapolate too much from animal studies. We urge investigators to use the most objective methods available to measure nerve regeneration. Recognizing these limitations, however, animal studies will continue to provide significant insights into PN regeneration and should point the way to improved clinical practice.

Intraoperative transluminal balloon dilatation permits simpler safer reconstructive surgery

The clinical and radiological features of seven patients in whom intraoperative transluminal balloon dilatation was used, are described. Indications and advantages of the technique are discussed.

Minima equalization: a useful strategy in automatic processing of microscopic images

Specifically stained features in microscopic images rarely have a unique range of grey levels which would permit selection of the features by simple thresholding. The spaces between features and immediately surrounding them are often as dark or darker than the more lightly stained features. An algorithm for minima equalization which facilitates the extraction and segmentation of such features was designed and is explained in intuitive terms. It is applied to the analysis of cross-sections of peripheral myelinated nerve fibers. It is shown that the binary image obtained can be combined with a gradient image to give a binary image which accurately reflects the thickness of the myelin in the original image. Using silver-impregnated nerve endings and bile canaliculi stained for thiamine pyrophosphatase, binary images like those prepared manually from thick specimens using a camera lucida can be obtained using the minima equalization procedure. The image processor is used to develop a composite image by combining images at various focal planes through the thick specimen. This image is then processed to obtain the binary image.

Bilateral unipapillary kidneys and haematuria

Images

Demonstration of differential immunohistochemical localization of the neuron-specific enolase antigen in rat pinealocytes

A refined method for the immunohistological demonstration of neuron-specific enolase (NSE) on 1- to 2-micron Epon-812 section gave characteristic staining of cerebral and cerebellar neurons. This method has made it possible to obtain a more detailed characterization of the heterogeneity of rat pinealocytes in the superficial portion of the rat pineal complex. Thirty adult male rats have been studied, five of which were used in a photometric analysis of the distribution of NSE. Pinealocytes stained either intensely or weakly for the NSE antigen and exhibited an uneven distribution within a given region. Further analysis of the gland revealed a distal to proximal decrease in stain intensity. It is suggested that the more strongly stained cells, being concentrated distally, are under sympathetic control.

Number and size of rat thyroid C cells: no effect of pinealectomy

A method for the estimation of the size and total number of calcitonin-containing cells (C cells) in the rat thyroid gland has been devised. The total area, the number of C cells per unit area, and the areal fraction of C cells were determined for the C cell region using step serial sections. From these data it was estimated that from 0.3 X 10(6) to 1.0 X 10(6) C cells were evenly divided between the two thyroid lobes. Approximately 150 micron3 of cytoplasm were associated with each of these cells. In comparison with sham-operated rats, pinealectomy had little effect on the number of C cells. In an experiment terminated in the summer, there was a statistically insignificant decrease 6 weeks postsurgery; no effect was seen at 12 weeks. On the other hand, a slight increase in the number of C cells was seen in January, 12 weeks postsurgery. The volume of cytoplasm per cell was not altered by pinealectomy.

"Synaptic" ribbons and spherules of the guinea pig pineal gland: inverse day/night differences in number

The present study deals with the functionally enigmatic "synaptic" ribbons and spherules of guinea pig pinealocytes. Whereas the ribbons have been shown to exhibit a 24-hr rhythmicity with low numbers during the day and high numbers at night, very little of a definitive nature is known about the spherules. Sixteen male guinea pigs of the Hartley strain were perfusion fixed, 8 between 0900-1100 hr, and 8 between 2100-2300 hr. The ribbons and spherules were counted in the pineal parenchyma of the proximal, intermediate, and distal regions. In confirmation of earlier studies, it was found that "synaptic" ribbons are equally abundant in the proximal, intermediate, and distal regions of the gland, during both the day and the night, and that they increase significantly in number at night when compared with daytime values. The spherules, by contrast, are more abundant proximally and are present in greater numbers during the day than at night. As ribbons and spherules are usually not found in one and the same pinealocytic profile, and based on previous electrophysiological studies, it is proposed that the ribbons are morphological markers of nocturnally active pinealocytes, whereas spherules characterize diurnally active pinealocytes.

Improvement of the butyl methacrylate-paraffin embedment

The excellent butyl methacrylate-paraffin method as an embedment for light microscopy has been technically improved. More uniform and reproducible polymerization has been obtained by using a vacuum oven to degas the polymerizing mixture and to replace the air with nitrogen at 650 Torr. The amount of benzoyl peroxide required must be determined for each batch of butyl methacrylate. A teflon lined, reusable metal mold and a method of one-step blocking of tissues in preparation for sectioning are also described.

Enhancement of immunohistochemical staining. Effects of serum volume and mixing

The present paper describes two simple procedures which enhance immunohistochemical staining. One is to cover the sections with a plastic film to keep the serum uniformly distributed and minimize its evaporation. Secondly, rocking of the slides has been introduced, causing the serum to flow back and forth under the plastic film. Using this system, it has been possible to test for the effect of mixing on an immunohistochemical reaction (the demonstration of calcitonin in thyroid C cells). It has been found that mixing definitely enhances the reaction during the first 8 h. No effect of serum volume was observed.

Anomalous occurrence of immunoreactive calcitonin cells in the thymus of the rat

In a study of the effect of pinealectomy on thyroid C-cell number, 8 animals out of 66 were found to have thymic tissue in close association with the thyroid. Cells containing immunoreactive calcitonin were found in all of the thyroids but in only one of the 8 pieces of thymus. These cells found in a piece of thymic tissue associated with the right thyroid lobe were located immediately under the capsule and did not form or associate with follicles. Unlike the other animals the rat with thymic calcitonin cells had an unequal distribution of C-cells between the left and right thyroid lobes, but the total number of thyroidal C-cells was the same as that of the other rats. Since the thymus proper was not examined in these 66 animals, ten additional rats were taken for such a study. Thyroid-associated thymic tissue was found in three of these, but none of these thymi showed any immunoreactive cells.

Responses of mouse spleen morphology to the growth of subcutaneously injected virally transformed cells

The changes in the fractional volume of six structural components in the spleens of Balb/C mice injected with Herpes simplex virus Type 2-transformed cells (H238 tumor cells) were quantitated during progressive tumor growth. Spleen stereology was performed at three time intervals during the early stages of tumor development. The results revealed that the volume of the compact myeloid tissue and reaction center of lymphoid nodules increased about four- to five-fold from 10 to 33 days after H238 tumor cell injection. A progressive increase was also seen in the red pulp volume. Although an increase in volume of the marginal zones around the lymphoid nodules was evident early during the test period, by day 33 the mean value was similar to the control value. These results indicate that the spleen undergoes significant morphological changes in three splenic components during progressive growth of a tumor produced by subcutaneous injection of a virally-transformed cell line.

Influence of development on the number of calcitonin-containing cells in the mouse thyroid

Calcitonin-containing cells in serial, 6-micrometer sections of the thyroid glands of Swiss Webster mice, at 1 day, 2 weeks, 4 weeks and 8 weeks of age, were demonstrated by an immunoperoxidase method, using antiserum to human calcitonin. C-cell nuclei were counted in every sixth section of both left and right lobes. The average number of C-cells counted in the thyroid glands of 8-week-old animals was 18-fold, 5.5-fold and 2.5-fold greater than the number observed in 1-day, 2-week and 4-week-old animals, respectively. C-cell concentration was found to be greatest in 4-week-old mice. Mitoses of C-cells were observed in animals which were 1 day, 2 weeks and four weeks old. No mitotic figures were seen in 8-week-old animals. A few C-cells were seen in close association with neurons. The volume of the thyroid glands of 8-week-old animals was about 14-, 4- and 3-fold greater than the volume in the 1-day-old, 2-week-old and 4-week-old mice, respectively. These changes in the C-cell population during development provide a model for the study of C-cell proliferation and storage of calcitonin.