Does storage affect epifluorescence microscopic counts of total bacteria in freshwater samples?

Preservation with formalin and storage at 4 degrees C of freshwater samples, associated with sonication before counting, proved to be efficient for a few days of storage (no differences with the initial cell count within 7 d of storage); after 8 months, 95% of the initial count was preserved. This procedure always gave higher counts than those obtained from the freezing technique of filter storage at -18 degrees C after sample filtration.

The role of Ca ions in restoration of the structure of interphase and mitotic chromosomes in PK living cells after hypotonic stress

The dynamics of mitotic chromosome and interphase chromatin recondensation in living PK cells during their adaptation to hypotonic medium was studied. The recondensation process was found to be slowed down by the modification of plasma membrane with low concentrations of glutaraldehyde, while osmotic reactions of glutaraldehyde-treated cells remain unchanged. The effect of glutaraldehyde can be rapidly reversed by the addition of Ca(2+)-ionophore A23187. Intracellular Ca(2+)measurements show that the adaptation to hypotonic shock is accompanied by restoration of free Ca concentration, whereas the delay of chromatin condensation in glutaraldehyde-treated cells is paralleled by the decrease of Ca level. The mechanisms implying the role of low concentration of Ca(2+)in chromatin compactization in vivo are discussed.

Glutathione levels in primary glial cultures: monochlorobimane provides evidence of cell type-specific distribution

Because glutathione (GSH) levels in glia play an important role in cellular defense against oxidative and nitrosative stress, the present study was designed to study GSH levels in the primary glial cell cultures. Here we used fluorescence microscopy and spectroscopy with monochlorobimane for measurement of intracellular glutathione content. Monochlorobimane showed high specificity for GSH with very little binding to protein sulphydryls as ascertained from the low fluorescence intensity of the protein fraction of the cells as well as from the low fluorescence of the GSH-depleted cells. The formation of the monochlorobimane-glutathione conjugate was observed to be enzymatically catalyzed as seen from its higher rate of formation in the presence of cell homogenate. A monochlorobimane concentration of 60 microM was used for conjugation of cellular GSH; at higher mBCl concentrations there was no appreciable increase in fluorescence. Therefore, cultures were treated with 60 microM mBCl for an incubation time of 20 min (beyond this time, export of the bimane-glutathione adduct was significantly large) and examined by fluorescence microscopy. This adduct could be fixed with a mixture of paraformaldehyde and glutaraldehyde, and excellent fixation was observed with 4% paraformaldehyde and 0.2% glutaraldehyde. Analysis of the fluorescence images revealed differences in fluorescence intensity between astro- and microglial cells, which were identified by glial fibrilliary acidic protein and OX42 staining, respectively. Microglial cells isolated from primary glial cultures were found to have higher GSH content than astrocytes. Biochemical determination of GSH levels in microglia isolated from primary glial cultures corroborated this fact. From our findings it seems that owing to the greater intracellular concentration of reactive oxygen and nitrogen species to which microglia are subjected, especially under conditions of inflammation, this cell type is fortified with higher GSH levels as a means to combat oxidative and nitrosative stress.

Immunocytochemical localization of histamine in enterochromaffin-like (ECL) cells in rat oxyntic mucosa: a transmission electron microscopy study using monoclonal antibodies and conventional glutaraldehyde-based fixation

Histamine (HA), contained in the enterochromaffin-like (ECL) cells of the gastric mucosa in animals, plays an important role in gastric acid secretion, although methods for its exact morphological localization are still lacking. We used a pre-embedding indirect immunoperoxidase approach to define the fine structural localization of HA in rat oxyntic mucosa that was fixed with a glutaraldehyde-based fixative and HA monoclonal antibodies (MAbs AHA-1 and 2). Transmission electron microscopy showed that the peroxidase endproduct not only was concentrated in the cores of cytoplasmic granules but also was distributed to a high degree in the cytoplasm peripheral to the granules of the ECL cells. These results suggest that in ECL cells HA is enzymatically synthesized in the cytoplasm, then is transported and stored in the cores of the granules before its release from the basal lamina. The present HA immunoelectron microscopic method with MAbs would be applicable more generally to the ultrastructural identification of HA-containing cells.

Quantitative immunocytochemical study of blood-brain barrier glucose transporter (GLUT-1) in four regions of mouse brain

Application of immunogold cytochemistry revealed polar (asymmetric) distribution of GLUT-1 in mouse brain microvascular endothelia, representing the anatomic site of the blood-brain barrier (BBB). This polarity was manifested by an approximately threefold higher immunolabeling density of the abluminal than the luminal plasma membrane of the endothelial cells. The immunoreaction for GLUT-1 in nonbarrier continuous (skeletal muscle) or fenestrated (brain circumventricular organs) microvascular endothelial cells was absent. In the choroid plexus, the basolateral plasmalemma of the epithelial cells was labeled more intensely than the vascular fenestrated endothelium. Addition of morphometry to the applied immunogold technique makes it possible for even subtle differences to be revealed in the density of immunolabeling for GLUT-1 in blood microvessels located in four brain regions. We found that the density of immunosignals in the microvessels supplying the cerebral cortex, hippocampus, and cerebellum was essentially similar, whereas in the olfactory bulb it was significantly lower. Asymmetric distribution of GLUT-1 in the endothelial plasma membranes presumably leads to a reduced concentration of glucose molecules in the endothelial cells compared to blood plasma and also secures their more rapid transport across the abluminal plasmalemma to the brain parenchyma.

Use of fixed cells in cell contact-dependent cytotoxicity assays for TNF: a cautionary report

The use of fixed effector cells or cell membrane preparations in assays to study cell surface TNF-mediated immunological effects has been widespread for more than a decade. The assumption has always been made that observed effects of fixed cells are due to the cell surface TNF molecule. Here we report that paraformaldehyde-fixed, LPS-stimulated RAW264.7 cells release a factor that causes cytotoxicity against TNF sensitive WEHI-164 cells. The factor was neutralized by soluble TNF receptors as well as antibody and could not be removed by ultracentrifugation at 100,000 x g, and is therefore likely to be a form of soluble TNF. This has important implications for the interpretation of these assays, given that cell surface TNF is thought to exert biological effects through a different signaling mechanism than soluble TNF.

TUNEL staining of inner ear structures may reflect autolysis, not apoptosis

A recent study (Usami et al., 1997) using the TUNEL method has suggested that age-related cell death in the senescence-accelerated mouse inner ear is due to apoptosis. TUNEL staining detects not only apoptosis but also late necrosis or autolysis because it detects DNA breaks. Autolysis may occur in inner ear structures during fixation. To determine whether or not age-related cell death is due to apoptosis, TUNEL staining of the inner ear of normal mice should be understood. However, studies of TUNEL staining of the normal inner ear have not yet been reported. We investigated whether the fixation method or the interval between the death of normal mice and the initiation of fixation influences the results of TUNEL staining of the inner ear. Marginal cells of the stria vascularis and hair cells of the saccule were TUNEL-positive, irrespective of the fixation method or the interval between death and fixation. Interdental cells, Reissner membrane cells, fibrocytes in the suprastrial region, and inner and outer hair cells were also occasionally stained. Transmission electron microscopy showed no morphological characteristics of apoptosis in the hair cells of the saccule. Moreover, patterns of TUNEL staining in the normal and senescence-accelerated mouse inner ear were similar. These stained tissues may require a high level of oxygen, making them more susceptible to autolysis. We concluded that the results of TUNEL staining in the inner ear require confirmation by morphological studies.

Activity of O6-methylguanine DNA methyltransferase in mononuclear blood cells of formaldehyde-exposed medical students

A recent study reported that exposure of student embalmers in Cincinnati to high concentrations of formaldehyde (2 mg/m3) reduced the activity of the DNA repair protein O6-methylguanine DNA methyltransferase (MGMT). Reduction in a DNA repair enzyme may strongly increase the cancer risk not only with respect to the repair-enzyme causing agent but with respect to all carcinogens causing lesions subject to repair by the enzyme in question. Thus, we examined whether formaldehyde exposure of 57 medical students during their anatomy course at two different Universities in Germany influenced MGMT activity in mononuclear blood cells. Mean formaldehyde exposure of 41 students was 0.2 +/- 0.05 mg/m3 for 6 h per week. MGMT activity was 133.2 +/- 14.9 fmol MGMT/10(6) cells before the beginning of the formaldehyde exposure, 131.1 +/- 15.8 fmol MGMT/10(6) cells after 50 days (P = 0.56) and 128.2 +/- 19.0 fmol MGMT/10(6) cells after 111 days of exposure (P = 0.92). Similarly, no significant influence of formaldehyde exposure was observed, when smoking habits, alcohol consumption, allergic disease and sex of students were considered. In addition no significant difference was obtained in MGMT activity between 16 students with mean formaldehyde exposure of 0.8 +/- 0.6 mg/m3 and students without formaldehyde exposure (n = 51; P = 0.37). In conclusion, exposure of the medical students in western Europe to formaldehyde did not decrease MGMT activity in mononuclear blood cells.

Effectiveness of different anticalcification treatments for stentless aortic bioprostheses

BACKGROUND

New anticalcification treatments for stentless bioprostheses have not yet been compared independently.

MATERIAL AND METHODS

The No-reacts (Biocor), AOA (Medtronic Freestyle), and BiLinx (SJM Toronto SPV II) methods were studied and compared with a control group. Aortic valve leaflet and aortic root tissue was subcutaneously implanted in 60 male, 21-days-old Sprague-Dawley rats. Calcium content was quantified using inductively coupled plasma spectrophotometry.

RESULTS

No infections occurred. Low levels of calcium were measured in aortic valve leaflet tissue for all methods (0.4 to 1.5 mg/g dry weight) in comparison to the control group (225 mg/g), p < 0.01. Calcification of aortic root tissue was low in the Bilinx group (2.4 mg/g, p < 0.01), whereas calcium levels were high in all other groups (104 to 127 mg/g).

CONCLUSIONS

Calcification of aortic valve leaflets was significantly reduced by all new anticalcification treatments, whereas aortic root calcification was only reduced by inhibition of cellular calcification (BiLinx). Maximum anticalcification properties of both leaflet and aortic root are important, as these are considered a functional unit in stentless bioprostheses.

Synaptophysin immunocytochemistry with thermal intensification: a marker of terminal axonal maturation in the human fetal nervous system

Synaptophysin is a protein of synaptic vesicles and may be demonstrated in tissue sections of human brain and spinal cord by immunocytochemistry using a monoclonal antibody. Synaptophysin immunoreactivity was studied in paraffin-embedded sections of the central nervous system (CNS) in 14 normal human fetuses and neonates ranging in age from 8 to 41 weeks gestation, and in three brains with heterotopic neurons or malformations. A progressive expression of synaptophysin is seen in axonal terminals within grey matter in various parts of the CNS, beginning in the ventral horns of the spinal cord and brainstem tegmentum at 12-14 weeks. In the cerebellum, the molecular layer shows a band of reactivity from 18 weeks; by term two parallel bands of synaptophysin are seen in the molecular layer and reactivity also is demonstrated in the Purkinje and internal granular layers. In the cerebral neocortex, the molecular zone has weak synaptophysin reactivity as early as 10 weeks, though reactivity is not detected in the deep layers of the cortical plate until 19 weeks and in layers 2-4 until 25 weeks gestation. Synaptophysin reactivity is strong at the surface of neurons but not detected in their somatic cytoplasm; coarsely beaded reactivity within the neuropil probably corresponds to synaptic vesicles in terminal axons. Similar granular synaptophysin reactivity is seen around heterotopic neurons in the subcortical white matter, in dysgenesis of the cerebellar cortex and in the residual anencephalic forebrain. Thermal intensification by heating the incubating solution in a microwave oven often enhances immunoreactivity because of more complete antigen retrieval and is recommended for tissue stored in formalin or in paraffin for long periods. Synaptophysin provides a useful tissue marker of synaptogenesis during normal development and in cerebral dysgeneses, and may provide useful correlations with functional imaging of the brain in living patients. Used in conjunction with other neuronal markers, the expression of synaptophysin in terminal axons of distant neurons, in temporal relation to the maturation of the neurons they innervate, may provide clues to the pathogenesis of epilepsy in early infancy.

Tannic acid and thiocarbohydrazide as structural reinforcement agents in the preparation of rabbit knee articular cartilage for the scanning electron microscope

Samples from seven sectors of the rabbit knee articular cartilage were shaved and prepared for the scanning electron microscope using either tannic acid, thiocarbohydrazide or nothing (control). Surface morphology was found to be more typical to a given sector and less so to a specific preparation procedure. Rough areas were recorded from load-bearing sectors, while smooth areas appeared on load-free ones. However, fibrillations were discerned on control load-bearing sectors only, and pits and humps were never detected. Tannic acid and thiocarbohydrazide may have exerted their structural reinforcing effect on the tissue preservation by enhancing the binding of osmium tetroxide to it, possibly along with that of other soluble tissue constituents.

Association of matrix acid and alkaline phosphatases with mineralization of cartilage and endochondral bone

The activities of acid and alkaline phosphatases were localized by enzyme histochemistry in the chondroepiphyses of 5 week old rabbits. Using paraformaldehyde-lysine-periodate as fixative, the activity of acid phosphatase was particularly well preserved and could be demonstrated not only in osteoclasts, but also in chondrocytes as well as in the cartilage and early endochondral matrices. The acid phosphatase in the chondrocytes and the matrix was tartrate-resistant, but inhibited by 2 mM sodium fluoride, whereas for osteoclasts 50-100 mM sodium fluoride were required for inhibition. Simultaneous localisation of both acid and alkaline phosphatase activities was possible in tissue that had been fixed in 85% ethanol and processed immediately. In the growth plates of the secondary ossification centre and the physis, there was a sequential localisation of the two phosphatases associated with chondrocyte maturation. The matrix surrounding immature epiphyseal chondrocytes or resting/proliferating growth plate chondrocytes contained weak acid phosphatase activity. Maturing chondrocytes were positive for alkaline phosphatase which spread to the matrix in the pre-mineralizing zone, in a pattern that was consistent with the known location of matrix vesicles. The region of strong alkaline phosphatase activity was the precise region where acid phosphatase activity was reduced. With the onset of cartilage calcification, alkaline phosphatase activity disappeared, but strong acid phosphatase activity was found in close association with the early mineral deposition. Acid phosphatase activity was also present in the matrix of the endochondral bone, but was only found in early spicules which had recently mineralised. The results suggest that alkaline phosphatase activity is required in preparation of mineralization, whereas acid phosphatase activity might have a contributory role during the early progression of mineral formation.

Comparison of different anticalcification treatments for stentless bioprostheses

BACKGROUND

New anticalcificant treatments have been developed because tissue calcification is a major contributing factor for bioprosthetic valve failure.

METHODS

Aortic valve leaflet and aortic root tissue samples from stentless bioprostheses treated with No-React (Biocor, Belo Horizonte, Brazil), AOA (Medtronic freestyle, Minneapolis, MN), and BiLinx (St. Jude Medical, St. Paul, MN) were compared to a control group by subcutaneous implantation in 60 male weanling Sprague-Dawley rats.

RESULTS

Calcium levels were in the range of 0.3 to 2.2 mg/g dry tissue at 3 and 12 weeks in all three treated aortic valve leaflet implants. The BiLinx treatment proved anticalcificant effectiveness on aortic root samples as well. There were statistically significant differences for valve leaflet tissue samples: No-React = AOA < BiLinx < < Control and for aortic root tissue samples: BiLinx < < AOA < Control = No-React.

CONCLUSION

Calcification of aortic valve leaflets was significantly reduced by all new anticalcificant treatments. Inhibition of cellular calcification (BiLinx) resulted in additional reduction of aortic root calcification. Maximum anticalcificant properties upon both leaflet and aortic root is important as these are considered a functional unit in stentless bioprostheses.

Carnoy's fixative reduces the number of chymase-positive cells in immunocytochemical staining of cord-blood-derived human cultured mast cells

KleinJan et al. (Allergy 1996;51:614-20) reported that Carnoy's fixative reduced the number of chymase-positive mast cells in the nasal mucosa. Therefore, in the present study, we investigated whether Carnoy's fixative reduces the number of chymase-positive cells from cord-blood-derived human cultured mast cells when compared with other types of fixatives. Human mast cells were obtained by culturing cord-blood-derived CD34-positive cells in the presence of stem cell factor and interleukin-6. Staining procedures of the cells in fixation with Carnoy's fixative and with other fixatives gave no differences among the number of tryptase-positive cells, whereas fixation with Carnoy's fixative for 15 min gave a significant decrease in the number of chymase-positive cells compared with acetone for 10 min. The number of chymase-positive cells decreased in a time-dependent manner under fixation with Carnoy's fixative, indicating that Carnoy's fixative had a negative effect on the number of chymase-positive cells from cord-blood-derived human cultured mast cells.

Medtronic Freestyle aortic root bioprosthesis: Implant techniques

BACKGROUND

The Medtronic Freestyle aortic root bioprosthesis is a complete porcine aortic root to allow implantation (1) as a subcoronary valve replacement by removing graft sinus aorta, (2) as a cylinder with the sinotubular junction intact within the aorta (root inclusion), or (3) as a complete aortic root replacement. The choice among the three implant techniques depends on surgeon preference or upon the pathology encountered. The advantages and differences among the three implant techniques are examined.

METHODS

The Medtronic Freestyle bioprosthesis was implanted in 1163 patients in a Food and Drug administration (FDA) clinical trial between August 1992 and October 1997. There were 21 centers in the international trial using a single data repository. Clinical data was collected prior to and at operation, at 3 to 6 months and annually. The data were compiled and statistical analysis performed at the data center.

RESULTS

Patients having subcoronary valve implants were older (80% > 65 years) and aortic occlusion time was about 20 minutes less than the other methods. Patients having aortic root replacement presented with more aortic valve insufficiency (20%). Pathology of the aortic root and ascending aorta requiring repair was 26%, and larger (27 mm) valves were used in 40% of patients. Risk of operation was lowest (5.0%) with subcoronary valve implants and highest (11.7%) with root replacement technique. Thromboembolism was higher, early and late, with root inclusion (3.0, 3.9%/patient per year) and root replacement (3.2, 3.0%/patient per year) than for subcoronary implants (1.8, 1.6%/patient per year). There were more patients taking warfarin at the 4-year point with root inclusion (20%) or root replacement techniques (24%) than among patients having subcoronary implants (14%). Explants of the valve occurred in 2% of patients, none of whom had aortic root replacement.

CONCLUSIONS

The Medtronic Freestyle bioprosthesis is an effective and versatile device for replacement of the aortic valve. It offers implant techniques that can treat the aortic root pathology encountered at surgery and allows the operation to proceed according to surgeon preference.

The stentless porcine valve

Recognition of the long-term results of homografts has brought about a renewed interest in stentless valves. This has been matched by the introduction of several glutaraldehyde preserved porcine stentless prostheses. The early experience indicates that these valves are technically somewhat simpler to insert than homografts and are associated with satisfactory early and immediate-term results. In particular, they appear to offer an earlier and more complete resolution of left ventricular hypertrophy. Correct insertion of a stentless porcine valve needs meticulous attention to detail and awareness of the precise anatomical features of the aortic root, which is a complex structure. Although the myocardial ischemic and cardiopulmonary bypass times are longer for the more complex insertion of this prosthesis, our studies indicate that this has no serious disadvantage to the patient and is more than matched by an improved hemodynamic performance associated with more stable left ventricular function. The theoretical advantages of a stentless valve substitute in the aortic position seem clear. Further detailed prospective studies are needed to report on the long-term performance of this valve.

Flow cytometric DNA analysis with cytokeratin gating of formalin-fixed deparaffinized breast cancer nuclei

The "gold standard" inflow cytometric DNA analysis of breast cancer uses fresh tumor cells simultaneously labeled for cytokeratin (CK) and DNA. We developed a 2-parameter CK-DNA flow assay suitable for archival, paraffin-embedded tissue (PT). Six anti-CK monoclonal antibodies were tested by immunocytochemistry and our assay for staining of nuclei extracted from PT breast cancers by combination pepsin-trypsin digestion. Clone CAM 5.2 was inadequate for PT nuclear suspensions, but a cocktail of 2 anti-CK clones (AE1/AE3 and KL-1) distinguished epithelial from nonepithelial nuclei in 2-parameter flow dot plots. We studied 82 routine PT breast tumors by our assay and used a univariate flow DNA histogram based on fresh biopsy tissue for comparison. Three histogram data quality indicators were improved. A trend toward higher S-phase fractions was found for DNA diploid PT tumors, although when inflammation was evident histologically, the increment in S-phase fraction with gating was often marked. CK gating identified PT tumors containing concurrent CK-positive DNA diploid and nondiploid populations (27 of 56 DNA nondiploid histograms). By excluding nonepithelial nuclei, 2-color CK-DNA flow methods may increase the accuracy of ploidy and S-phase fraction measurements. Our method appears superior to previous techniques using clone CAM 5.2 for labeling of archival breast cancers.

An in situ cytochemical evaluation of blood-brain barrier sodium, potassium-activated adenosine triphosphatase polarity

It is presently believed that sodium, potassium-activated adenosine triphosphatase (Na+, K+-ATPase) is localized on the abluminal plasma membrane of brain endothelial cells. But there have been contrary reports from some cytochemical studies. We examined the localization of the enzyme in rat cerebral microvessel endothelium using the in situ model originally employed to establish the abluminal polarity concept. Alterations in fixation and incubation media from the original reports were conducted to determine the effect on localization pattern. With the Ernst indirect incubation method as originally used, three types of localization patterns were obtained: abluminal only, luminal only, and on both surfaces of endothelial cells. With the direct incubation method of Mayahara, reaction product was seen on both surfaces. Reduction in fixation time followed by the use of the indirect incubation method resulted in a complete loss of the reaction product. The same reduction in fixation time followed by the use of the direct method did not alter the localization pattern of the enzyme. Our results demonstrated that Na+, K+-ATPase is localized on both surfaces of brain endothelial cells. The localization pattern of Na+, K+-ATPase is significantly dependent upon fixation and the incubation medium used in the in situ model. Data discrepancies for the enzyme as reported in the literature appear to be caused by differences in cytochemical protocols, rather than the biological reasons advocated by other investigators. We conclude that past cytochemical reports of blood-brain barrier (BBB) Na+, K+-ATPase abluminal localization were incomplete. The currently held abluminal polarity theory of the enzyme needs to be reexamined. Past basic and clinical cytochemical studies of BBB Na+, K+-ATPase should be viewed and interpreted with caution.

Computer assisted morphometric analysis of ram sperm heads: evaluation of different fixative techniques

The recent development of automated systems for morphometric sperm head analysis has provided a series of objective parameters which have facilitated the standardization of morphological semen evaluation. This current work attempts to establish the optimum fixing conditions for the morphometric characterization of ram spermatozoa. Ejaculates were obtained from 5 Merino rams used for periodic collection of semen and were diluted at 1:50 with TEST medium. Air-dried smears were fixed either in ethanol-ether (1:1), 50% methanol, 2% glutaraldehyde or SUZA fixative, in which case the smear was pretreated with chloramine. The samples were then stained with commercial kit Hemacolor. Once the preparations had been mounted, they were analyzed with the Sperm Class Analyzer automatic sperm morphometry analysis system (ASMA). The minimum number of sperm cells analyzed per sample was 100. The parameters evaluated were the area, perimeter, length, width, shape factor and mass. The results showed significant differences in sperm head dimensions between the 4 fixation techniques, with the lowest values for all parameters corresponding to the SUZA fixative, followed by glutaraldehyde, methanol, and finally ethanol-ether. In addition, there were significant variations between animals. It can, therefore, be concluded that the working protocol must be defined when performing morphometric analysis of ram semen and that the results obtained under different conditions of fixation cannot be entirely extrapolated. Equally, the high variability among individuals suggests that, in a species like the ram with a low index of teratozoospermia, there is a need for a revision of the classic definition of normality, which should include morphometric data.

DNA damage caused by common cytological fixatives

Tissues from nine species of plants and fungi were treated separately with eight solutions, including seven cytological fixatives (3.7% formaldehyde at pH 3.0 and 7.0, FAA at pH 3.0 and 7. 0, 1% glutaraldehyde at pH 3.0 and 7.0, and Lavdowsky's fluid at pH 3.0) and one storage buffer (SED=NaCl-EDTA-DMSO, pH 7.0). DNA from untreated tissue and SED-treated tissue was of high molecular weight (>50 kb). DNA from glutaraldehyde-treated tissues averaged 20 kb in length, while DNA from all other treatments averaged less than 8 kb in length. Each DNA was subjected to amplification using the polymerase chain reaction, followed by sequencing of 250 bp near the 3' end of the nuclear rRNA small subunit gene. Glutaraldehyde treatments (at pH 3.0 and 7.0) produced damaged bases at rates of 0. 0% to less than 0.1%. Treatments with Lavdowsky's fluid (containing mercuric chloride), FAA at pH 7.0, and SED produced rates of 0.0% to 3.6%. FAA at pH 3.0 produced rates of 7.6% to 15.6%. Nearly 100 attempts to amplify from specimens treated with 3.7% formaldehyde (at pH 3.0 and 7.0) failed, indicating extreme damage to the DNA.

Diameters of the main excretory ducts of the adult human submandibular and parotid gland: a histologic study

In assessing new minimally invasive diagnostic techniques (duct endoscopy) and therapy (lithotripsy), it is of importance to know the true dimensions of the excretory ducts. Twenty-five ducts of the parotid gland and 20 ducts of the submandibular gland were examined histologically at different points of their anatomic course, and their in vivo diameters were evaluated with the use of a previously determined formalin-induced shrinking-factor. The mean diameter of Stensen's duct at four different points along its length ranged between 1.4 mm and 0.5 mm, with a maximum of 2.3 mm and a minimum of 0.1 mm, depending on the site. A narrowing at the middle of the duct was striking. In all preparations examined, the minimum width of the excretory duct was located at the ostium. In Wharton's duct the narrowest duct diameter was also identified at the ostium. The mean values for the duct diameters ranged between 1.5 mm and 0.5 mm. The largest duct diameter reached 2.2 mm; the smallest one, 0.2 mm. For diagnostic and therapeutic purposes, endoscopes, balloon catheters, and stone-extraction-baskets probably should, despite the extensibility of the duct, conform as much as possible to the physiologic duct widths. A diameter of 1.2 mm should be aimed at as an upper limit for these instruments. Our findings also suggest that, in the case of salivary stone lithotripsy, the best results will be achieved when the maximum size of stone fragments does not exceed 1.2 mm.

Localization of ryanodine receptors in smooth muscle

The ryanodine receptor (RyR) in aortic and vas deferens smooth muscle was localized using immunofluorescence confocal microscopy and immunoelectron microscopy. Indirect immunofluorescent labeling of aortic smooth muscle with anti-RyR antibodies showed a patchy network-like staining pattern throughout the cell cytoplasm, excluding nuclei, in aortic smooth muscle and localized predominantly to the cell periphery in the vas deferens. This distribution is consistent with that of the sarcoplasmic reticulum (SR) network, as demonstrated by electron micrographs of osmium ferrocyanide-stained SR in the two smooth muscles. Immunoelectron microscopy of vas deferens smooth muscle showed anti-RyR antibodies localized to both the sparse central and predominant peripheral SR elements. We conclude that RyR-Ca2+-release channels are present in both the peripheral and central SR in aortic and vas deferens smooth muscle. This distribution is consistent with the possibility that both regions are release sites, as indicated by results of electron probe analysis, which show a decrease in the Ca2+ content of both peripheral and internal SR in stimulated smooth muscles. The complex distribution of inositol 1,4,5-trisphosphate and ryanodine receptors (present study) is compatible with their proposed roles as agonist-induced Ca2+-release channels and origins of Ca2+ sparks, Ca2+ oscillations, and Ca2+ waves.

Comparative analysis of human and macaque monkey CD4: differences in formaldehyde lability and conformation

Here we characterized macaque monkey CD4 by flow cytometry. The results showed that relatively lower fluorescence intensity was observed depending on the monoclonal antibodies (mAbs) used for staining; Leu-3a exhibited four-fold lower intensity than Nu-Th/i, and that formaldehyde fixation dramatically reduced fluorescence intensity of macaque CD4+ cells stained with Leu-3a but not of human cells. Nu-Th/i is therefore preferable for the analysis of macaque CD4. Pretreatment of either mAb inhibited the other mAb binding to human CD4. On the contrary, Nu-Th/i inhibited Leu-3a binding but Leu-3a poorly blocked Nu-Th/i binding to the macaque CD4. These results indicate that Leu-3a and Nu-Th/i epitopes are conserved in macaque CD4 but Leu-3a epitope is conformationally cryptic and/or fragile, resulting in the lower affinity. Amino acid sequence alignment of CD4 domain 1 shows that the substitutions outside the linear Leu-3a epitope may determine these characteristics of macaque CD4.