Percent Glutaraldehyde Research Articles

The effect of transient proanthocyanidins preconditioning on the cross-linking and mechanical properties of demineralized dentin

Proanthocyanidin-based preconditioners were prepared by adding powdered proanthocyanidins-rich grape seed extract to various solvents at different concentrations. Demineralized dentin specimens were preconditioned for 20, 30, 60 or 120s, followed by the evaluation of their cross-linking degree, mechanical properties and micromorphology. The cross-linking degree of the demineralized dentin collagen exhibited concentration- and time- dependent increase after preconditioning treatment, irrespective of the preconditioner and the solvent. When treated for the same exposure time, specimens after 15% proanthocyanidins preconditioning resulted in the highest mean ultimate tensile strength compared with all the other groups tested. Five percent glutaraldehyde control group produced the highest cross-linking degree, but the ultimate tensile strength was lower than that of 15% proanthocyanidins group. The field emission scanning electron microscopy confirmed that the demineralized dentin collagen was in a homogeneous and regular arrangement after preconditioning and maintained expanding, regardless of the surface moisture conditions.

Using Extracted Teeth for Research: The Effect of Storage Medium and Sterilization on Dentin Bond Strengths

The Centers for Disease Control and Prevention has adopted guidelines for infection control of extracted teeth used for research and teaching, requiring that teeth be sterilized before use. The authors conducted a study to test the null hypothesis that the storage medium and sterilization method have no effect on composite-to-dentin bond strengths. The authors collected 170 bovine incisors, cleaned them and placed them randomly into one of six storage media at 37 degrees C for 60 days: distilled water (dH(2)O), 0.9 percent sodium chloride, 0.5 percent chloramine-T, 5.25 percent sodium hypochlorite (NaClO), 2 percent glutaraldehyde and 10 percent formalin. For sterilization, they autoclaved a subset of 10 specimens from every sample, while they stored another subset of 10 specimens from every sample (except for the 10 percent formalin sample) in 10 percent formalin for 14 days. The authors then embedded the specimens in epoxy and ground flat the facial surface to expose middle-depth dentin, which they polished to 600 grit. They used a dental adhesive to apply composite to the exposed dentin. The authors tested the composite-to-dentin shear bond strength 24 hours after bonding. They analyzed the data using global analysis of variance and, when appropriate, multiple post hoc tests (P = .05). Storage in NaClO resulted in significantly lower bond strength than that of the other treatment specimens. Sterilization with the autoclave negatively affected the bond strength of specimens stored initially in dH(2)O or 10 percent formalin, while sterilization with formalin alone had no significant effect on bond strengths. Storing bovine teeth in 5.25 percent NaClO may negatively affect composite-to-dentin bond strengths. Immersion in 10 percent formalin might be the best option for storage and sterilization of bovine teeth that are to be used in dental bonding studies in vitro.

Electron micrographic study of the removal of Trypanosoma cruzi from blood products by leukodepletion filters

Leukodepletion filters have been used to reduce the number of Trypanosoma cruzi in blood products in spite of the fact that while circulating in blood, these organisms are not contained within WBCs. We recently demonstrated by electron microscopy that leukodepletion filters remove the free extracellular form of the Leishmania promastigote, which has a similar structure and surface charge to that of the T. cruzi trypomastigote. The mechanism of removal in the case of the Leishmania promastigote is via direct adherence of the promastigotes to filter fibers. In the case of Leishmania, the amasitgote form of the organism is contained within monocytes and is removed as WBCs are trapped within filters; however, we demonstrated that free amastigotes and promastigotes adhere to filter fibers and are also removed. To investigate the mechanism of removal of T. cruzi, trypomastigotes were added to plasma separated from a unit of fresh whole blood collected into CPD and then passed through whole-blood leukodepletion filters (WBF2, Pall, East Hills, NY). Immediately after filtration, fixation was accomplished by adding 4 percent formaldehyde-1 percent glutaraldehyde to the filters. Filters were opened, and intact sheets of fibers were removed for examination by transmission and scanning electron microscopy. Figure A shows multiple trypomastigotes adhering to filter fibers. (Scanning electron micrograph of flagellated T. cruzi trypomastigotes adherent to leukodepletion filter fibers after filtration. Organisms can be seen to adhere via both body and flagella [magnification 3000x].) Figures B and C demonstrate adherence of individual organisms to fibers. (Fig. B-Transmission electron micrograph showing a T. cruzi trypomastigote adhering to a leukodepletion filter fiber [magnification 4000x]; Fig. C-Scanning electron micrograph showing a T. cruzi trypomastigote adhering to a leukodepletion filter fiber. The undulating membrane of the trypomastigote can be seen clearly in this EM. The undulating membrane is an organelle present in trypanosome and trichomonad parasites. It is a fin-like extension of the cell membrane with the flagellar sheath and contains microtubules. The membrane undulates producing movement of the organism [magnification 25,000x].) This work demonstrates that the T. cruzi trypomastigote adheres to leukodepletion filter fibers in a similar way to that of the Leishmania promastigote. In contrast to a prior report of removal by predominantly mechanical means, we found that the predominant mechanism appears to be via adherence of trypomastigotes to filter fibers.

Comparison of the disinfectant efficacy of Perasafe® and 2% glutaraldehyde in in vitro tests

Two percent glutaraldehyde has been the reference disinfectant for high-level disinfection, but its frequent association with adverse effects has stimulated a search for newer disinfectants. We compared the efficacy of 2% glutaraldehyde with that of a new disinfectant formulation, Perasafe® (0.2% peracetic acid) in six in vitro tests: germicidal effect in a suspension of micro-organisms; using a microbe-contaminated metallic endodoncy file; an endoscope model; a modified capacity test; a sporicidal test, and corrosiveness on metallic instruments. Both products were effective germicides in 10–20min, completely destroying microbial inocula except for Mycobacterium and spores. Internal irrigation of endoscopes with 100mL of either was totally effective. Both substances resisted inactivation after repeated inoculation and did not corrode clean instruments; however, when organic matter was added the 0.2% peracetic acid formulation cleaned without corrosion, while 2% glutaraldehyde fixed the matter to the scalpel, causing corrosion within 2h. In summary, Perasafe® is a good substitute for 2% glutaraldehyde for high-level disinfection.

Synthesis and physicochemical analysis of gelatin-based hydrogels for drug carrier matrices

This study examined the interrelated effect of environmental pH, gelatin backbone modification and crosslinking modality on hydrogel morphology, surface hydrophilicity, in vitro swelling/degradation kinetics, in vitro drug release kinetics and in vivo degradation, inflammatory response and drug release activity. The percent glutaraldehyde fixation had a greater impact on the morphology of the dehydrated hydrogels than gelatin modification. Any decrease in percent glutaraldehyde fixation and/or modification of gelatin with polyethylene glycol dialdehyde (PEG-dial) and/or ethylenediaminetetraacetic dianhydride (EDTAD) increased hydrogel surface hydrophilicity. Swelling/degradation studies showed that modification of gelatin with PEG-dial generally increased the time to reach the maximum swelling weight ratio ( T max) and the time to failure by hydrolysis ( T fail), but had little effect on the maximum swelling weight ratio ( R max) and the weight ratio at failure ( R fail). Modification of gelatin with EDTAD generally had no effect on T max and T fail, but increased R max and R fail. Modification of gelatin with PEG-dial and EDTAD increased R max, but had no effect on T max, R fail, or T fail. Decreasing percent glutaraldehyde fixation generally increased R max and R fail but decreased T max and T fail. Decreasing environmental pH from 7.4 to 4.5 had no effect on any swelling/degradation properties. In vitro drug release studies showed that modification of gelatin with PEG-dial and/or EDTAD generally decreased the maximum mass ratio of drug released ( D max) and the time to reach D max ( T dmax). Percent glutaraldehyde fixation did not significantly affect D max or T dmax (except for EDTAD-modified gelatin hydrogels). In vivo studies showed that gelatin-based hydrogels elicited comparable levels of acute and chronic inflammatory response as that of the empty cage control by 21 d.

El cloruro de benzalconio: inaceptable para esterilizar o desinfectar instrumental médico o dental

To compare the sporicidal activity of benzalkonium chloride (BKC) with that of glutaraldehyde. A comparative study was conducted at the microbiology laboratory of Facultad de Odontología, Universidad Nacional Autónoma de México. Bacillus subtilis ATCC 9372 spores were exposed to these germicides (1 spore x mL) on a 0.22 mm filter. After completing the contact time the spores were washed and the filters were incubated on nutrient agar for 72 h at 37 degrees C. BKC did not eliminate B. subtilis spores at the concentration used, not even after increasing contact time to 15 h (900-fold the recommended time). Two percent glutaraldehyde destroyed spores only after 10 h of contact. Urea and sodium chloride showed no sporicidal activity. The results confirm that BKC lacks sporicidal activity and confirm that this quaternary ammonium compound is not able to "sterilize" or "disinfect" medical and dental instruments.

Ultrastructure of early axonal regeneration in an end-to-side neurorrhaphy model.

The ultrastructure of the early regenerative response in an end-to-side neurorrhaphy rat model was studied using transmission electron microscopy. The ipsilateral saphenous nerve was grafted to the sciatic nerve under the following conditions: Group 1, the epineurium and perineurium of the sciatic nerve remained intact; Group 2, an epineurial and perineurial window was created at the site of the lateral neurorrhaphy; Group 3, the same as in Group 2 and, in addition, the sciatic nerve sustained a partial neurectomy. Rats were perfused through the heart with fixative containing 2 percent paraformaldehyde and 2.5 percent glutaraldehyde in 0.1 M cacodylate buffer (pH 7.4) at 4, 8, 12, 24 and 48 hr after surgery. In Group 1, no regenerating axons were observed and the myelin sheath in the donor nerve did not demonstrate any degenerative changes through 48 hr. In Group 2, an increased diameter of the unmyelinated axons and growth cones was observed in the donor nerve proximal to the coaptation site after 12 hr. Degenerative changes in the myelin sheath were observed after 12 hr within the several layers under the coaptation site. In Group 3, many growth cone-like structures were observed in the area proximal to the coaptation site after 12 hr. After 24 hr, proximal regenerating axons elongated to the coaptation site and, at 48 hr, many regenerating nerves grew inside the Schwann cell basement membrane of the graft nerve. These results indicate that the perineurial window and nerve graft are the critical conditions for inciting nerve regeneration in the donor nerve.

Structural changes in rat aortic intima due to transmural pressure.

Huang et al. (1997) propose a new hypothesis and develop a mathematical model to explain rationally the in vitro and in situ measured changes (Tedgui and Lever, 1984; Baldwin and Wilson, 1993) in the hydraulic conductivity of the artery wall of rabbit aorta with transmural pressure. The model leads to the intriguing prediction that this hydraulic conductivity would decrease by one half if the thin intimal layer between the endothelium and the internal elastic lamina volume-compresses approximately fivefold. This paper presents the first measurements of the effect of transmural pressure on intimal layer thickness and shows that the intimal matrix is, indeed, surprisingly compressible. We perfusion-fixed rat thoracic aortas in situ with 2 percent glutaraldehyde solution at 0, 50, 100, or 150 mm Hg lumen pressure and sectioned for light and electron microscopic observations. Electron micrographs show a dramatic, nonlinear decrease in average intimal thickness, i.e., 0.62 +/- 0.26, 0.27 +/- 0.14, 0.15 +/- 0.10, and 0.12 +/- 0.07 (SD) micron for 0, 50, 100, and 150 mm Hg lumen pressure, respectively. The volume strain of the intima is more than 20 times greater than the radial strain of the artery wall due to hoop tension and two orders of magnitude greater than the consolidation of the artery wall as a whole assuming constant medial density (Chuong and Fung, 1984). Moreover, in both light and electron microscopic observations, it is easy to find numerous sites where the endothelium puckers into the fenestral pores at high lumen pressure, as predicted by the theory in Huang et al. (1997). In contrast, the average diameter of a fenestral pore increases only 10 percent as the lumen pressure is increased from 0 to 150 mm Hg. These results indicate that the thin intimal layer comprising less than 1 percent of the wall thickness can have a profound effect on the filtration properties of the wall due to the large change in Darcy permeability of the layer and the large reduction in the entrance area of the flow entering the fenestral pores, though the pores themselves experience only a minor enlargement due to hoop tension.

Glutaraldehyde colitis: radiologic findings.

Two percent glutaraldehyde on colonic mucosa may result in a toxic colitis, and the clinical features may mimic those of colonic ischemia. The study was performed to determine the radiologic appearance of glutaraldehyde-induced toxic colitis. A retrospective review was performed with the clinical and imaging findings in four patients with glutaraldehyde-induced colitis seen during a 6-year period. Patients developed a self-limited syndrome of cramps and abdominal pain, tenesmus, and rectal bleeding within 48 hours of uncomplicated sigmoidoscopy or colonoscopy. Sample cultures excluded enteric pathogens. Computed tomography (CT) demonstrated circumferential thickening of the colonic wall in a left-sided distribution in all patients. Heterogeneous mural enhancement (target-sign appearance) was noted in two patients. Follow-up CT studies confirmed resolution of mural wall thickening with conservative management. The clinical and radiologic features of glutaraldehyde-induced toxic colitis may mimic those of colonic ischemia. This complication should be suspected in patients who develop hemorrhagic colitis immediately after undergoing colonoscopy.

Disinfection of dental stone casts: Antimicrobial effects and physical property alterations

Objectives. The purpose of this study was to evaluate the effectiveness of disinfecting solutions incorporated into dental stone casts against a standard and representative group of microorganisms and to note changes in the physical properties of the casts.Methods. Irreversible hydrocolloid impressions were con-taminated individually with Escherichia coli, Staphylococcus aureus, Enterobacter cloacae, Pseudomonas aeruginosa, Klebsiella pneumoniae, Actinobacter calcoaceticus, Bacillus subtilis, Mycobacterium phlei and Candida albicans. Four readily available disinfecting solutions (glutaraldehyde, povidone-iodine, chlorhexidine and sodium hypochlorite) were added to the die stone mix used to pour up the impressions. The set cast surfaces were swabbed at 1 h and 24 h, the samples plated on agar and incubated at 37°C for 24 h and 3 d for M. phlei. Subsequently, colony forming units were counted. The physical properties assessed were setting time, setting expansion, compressive strength, detail reproduction and delayed expansion of the stone.Results. Only glutaraldehyde and povidone-iodine killed all contaminating microorganisms within 1 h, while the 1:5 dilution of sodium hypochlorite solution was equally effective after 24 h. Two percent glutaraldehyde was the most effective disinfectant with the least adverse effects on the physical properties of the set cast. Although povidone-iodine caused a decrease in the compressive strength of the set cast, it can be considered to be a sound alternative.Significance. This study supports the concept of incorporating disinfectants into model stone as a standard operating procedure for impressions of unknown history and, most sensibly, all dental impressions.

Characterization of Rehydrated Gelatin Gels

Five percent glutaraldehyde cross-linked gels have shown excellent blood compatibility as coatings for cardiac prostheses. A method was developed for producing thin dehydrated coatings using a proprietary dehydration procedure and ethylene oxide (EO) sterilization. The swollen surfaces of rehydrates versus wet (original) gels were compared. Within 30 min of saline rehydration, dry 30-50-microns films on textured surfaces became smooth, uniform, and comparable to original gelatin gels. Mechanical test results after rehydration showed values for strain remain unchanged (39.3 + 10.0 to 40.0 + 7.8%), but stress increased (2.79 + 1.21 to 4.22 + 1.60 dyne/cm2; p less than 0.01). The contact angle data reported gamma C values of 26.1 and 30.4 dyne/cm for original and rehydrated gels. Using a coulometric titrimeter, the measured water content of original gels was reduced from 85 to 3.4% after drying. Dried and saline rehydrated gels had a 73.2% moisture content. Gels shrank 8.8% of their original length after rehydration; however, the thickness of all pump coatings remained stable. Two-hour incubations with bovine platelet rich plasma showed no differences in platelet reactivity or morphology when compared to original gels. Light microscopy and scanning electron microscopy (SEM) showed no evidence of gel cracking or surface defects after pump endurance testing for 3 and 5 weeks. The process of dehydration eliminates the wet storage and sterility problems of such hydrogels and provides a stable film coating for a variety of blood-contacting substrates.

Intracellular Secretory Pathway and Ultrastructural Localization of Interstitial Procollagenase in Human Gingival Fibroblasts

Fibroblast-type collagenase, a neutral secretory metalloproteinase capable of cleaving interstitial collagen types 1-III, is expressed by a number of different cell types including fibroblasts, macrophages, osteoblasts, and keratinoyctes. To elucidate the secretory pathway of this enzyme, we examined the ultrastructural localization of this metalloproteinase in cultured human gingival fibroblasts, particularly the routing of the enzyme from the Golgi cisternae to the cell surface utilizing rabbit polyclonal antibodies raised against human fibroblast (pro)collagenase. For this purpose, one percent glutaraldehyde followed by gentle permeabilization with saponin gave superior preservation of both cellular morphology and intracellular antigenicity. At the light microscopic level, the reacting antibodies visualized by immunofluorescence and immunoperoxidase staining were localized intracellularly in the perinuclear region reflecting the Golgi apparatus. Immunoelectronmicroscopy using the pre-embedding technique and peroxidase or immunogold staining revealed electron dense label in large vacuoles indicating extended cisternae of the Golgi field. Vesicles were noted leaving the plasma membrane in long extensions. Moreover, intact vesicles containing the antibody reaction product appeared outside the membrane. In addition, most extracellular vesicular structures appeared empty of label suggesting that the collagenase had been liberated into the extracellular space. The latter observation was supported by the fact that the label was found also on the extracellular surface of the cells indicating a (re) association of collagenase with the outer cell membrane. These data demonstrate that the pathway of interstitial collagenase in human gingival fibroblasts is similiar to that of other secretory proteins.

Antitrophic properties of antihypertensive drugs may depend solely on their blood pressure-lowering capability: A comparative study of isradipine, hydralazine, and metoprolol

The objective of this study was to examine the effect of antihypertensive treatment on the structure of intramyocardial resistance vessels in spontaneously hypertensive rats. The rats were divided into four groups: one was used as control and the other three were treated from the age of four to 24 weeks with isradipine, hydralazine, and metoprolol, respectively. Half of the animals in each group were examined at the end of active treatment and the rest were examined three weeks later. The rats were anesthetized and killed during constant flow perfusion with 1 percent glutaraldehyde. The media index was determined by point counting. The media indices of rats treated with isradipine and hydralazine were significantly smaller than those of age-matched spontaneously hypertensive rat controls, whereas the media indices of rats in the metoprolol group did not differ significantly. Three weeks after treatment withdrawal, the media index tended to increase in all three groups, but the values for the isradipine and hydralazine groups were still significantly reduced. Non-invasive blood pressure measurements taken at the same time demonstrated a significant blood pressure reduction in all groups, although differences within each treatment group were evident. All pressures had stabilized on the level of spontaneously hypertensive rats three weeks after withdrawal. Thus, it is evident that both isradipine and hydralazine were able to prevent hypertrophy of intramyocardial vascular structure and continue to do so even after treatment withdrawal. This finding is consistent with previous findings, suggesting a close relationship between the extent of blood pressure reduction and the degree of prevention of vascular hypertrophy.

Ultrastructure of myoepithelial cell in parotid gland

Myoepithelial cells have been observed in the prostate, harderian, apocrine, exocrine sweat and mammary glands. Such cells and their numerous branching processes form basket-like structures around the glandular acini. Their shapes are quite different from structures seen either in spindleshaped smooth muscle cells or skeletal muscle cells. These myoepithelial cells lie on the epithelial side of the basement membrane in the glands. This presentation describes the ultrastructure of such myoepithelial cells which have been found also in the parotid gland carcinoma from a 45-year old patient.Specimens were cut into small pieces about 1 mm3 and immediately fixed in 4 percent glutaraldehyde in phosphate buffer for two hours, then post-fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812. Thin sections were stained with uranyl acetate and lead citrate. Ultrastructurally, the pattern of each individual cell showed wide variations.

The effects of glutaraldehyde cross-linking on the function of the adenylate cyclase complex of turkey erythrocytes

Glutaraldehyde appears to preferentially effect the activation processes of the adenylate cyclase complex of turkey erythrocyte membranes. The primary effect of low concentration (0.01 percent, 0.05 percent, and 0.1 percent) glutaryldehyde membrane treatment is to decrease catecholamine-stimulated cAMP formation. The effect can be blocked by prior activation of the system with isoproterenol + p[NH]ppG. 0.6 percent glutaraldehyde treatment of membranes has substantial effects on both F −- and catecholamine-stimulated cAMP production. The effects are blocked by prior activation of the adenylate cyclase complex with NaF, but not by isoproterenol + p[NH]ppG. Glutaraldehyde at these concentrations has no effect on Mn ++-stimulated cAMP formation. The data is discussed with respect to the organization of the major macromolecular components of the adenylate cyclase complex as it exists within the native membrane prior to and following activation of the system.

Efficacy of a simplified lower gastrointestinal flexible endoscope cleaning method.

Published guidelines from the Center for Disease Control (CDC) "strongly recommended" gas sterilization or 30 minutes of high-level disinfection with either 2 percent glutaraldehyde or 6 percent hydrogen peroxide following each flexible endoscope cleansing for proper care. The guidelines were proposed on the basis of previous CDC studies performed on glutaraldehyde disinfection of respiratory equipment. A prospective study was performed culturing flexible endoscopes following cannulation of the lower gastrointestinal tract and cleansing. A uniform endoscope cleansing method without gas sterilization or high-level disinfection was used between patients. Thirty aerobic and 30 anaerobic RODAC bacterial culturings revealed no obligate anaerobic organism growth and only sparse, aerobic, environmental and cutaneous organism growth. There were no instances of documented or suspected postendoscopy infectious complications. Our results indicate that high-level disinfection and gas sterilization of flexible endoscopes are not necessary to prevent bacterial disease transmission from patient to patient.

Glutaraldehyde pretreatment blocks phospholipase A 2 modulation of adrenergic receptors

Treatment of rat cerebral cortical membranes with phospholipase A 2 affects, in a parallel fashion, β-, α 1- and α 2-adrenergic receptor binding, but not the affinity of these receptors for their respective ligands. Pretreatment of membranes with 0.1 percent glutaraldehyde blocks the effects of phospholipase A 2 on adrenergic receptor binding. The results support the hypothesis that desensitization or “masking” of adrenergic receptors may involve changes in membrane lipid composition. Furthermore, glutaraldehyde may prove a useful tool in the investigation of the dynamic roles of lipids in receptor function and more specifically, their regulation and coupling to physiological events.

Ultrastructural study of a granular cell tumor from forearm

Granular cell tumors are frequently reported in different body locations. Some authors believed it to be a neoplasm derived from skeletal muscle and others propose the origin of these lesions are from fibroblasts, histocytes, mesenchymal cell, neuron or Schwann cells. So far the tumor cells origin is still controversial. The purpose of this report is to present a case showing the cellular fine structures and to propose a possible origin of the tumor cells.A tumor mass (5 x 3 cm) from the left forearm of a 49 year old white male was removed, cut into small pieces (about 1 mm3), immediately fixed in 4 percent glutaraldehyde in phosphate buffer for 2 hours, and then post fixed in 1 percent buffered osmium tetroxide for 1 hour. After dehydration, tissues were embedded in Epon 812.

A study on the fine structure of Clonorchus sinensis, a liver Fluke V. The mature spermatozoa

An ultrastructural study on the mature spermatozoa of Clonorchis sinensis was carried out. For this study, the liver flukes were collected from the livers of rabbits and rats artificially infected with the metacercariae obtained from the fresh water fish, Pseudorasbora parva. Six-month old worms were used. The collected liver flukes were washed with 0.85 percent saline solution and then immediately moved to cold 2 percent glutaraldehyde buffered with 0.l M Millonig's phosphate buffer (pH 7.4). The materials were dissected into appropriate pieces in the fixative about 30 minutes after beginning of the fixation. Two hours later the materials containing the seminal receptacle were rinsed several times with the buffer and were secondarily fixed with cold, buffered 1 percent osmium tetroxide for 2 hours. The fully fixed tissue blocks were dehydrated in a series of graded concentrations of acetone and were embedded in Epon 812 mixture. Thin sections obtained from LKB-5 ultramicrotome were stained with uranyl acetate and Reynold's lead citrate. Observations of the sections were carried out with JEM-100CX II electron microscope. In general, the mature sperm was long thread-like form with a sickle-shaped head. According to the longitudinal sectioned view of the sperm tail, the nucleus seemed to be spirally coiled and run a little far along the tail. The acrosome was not observed. The cytoplasm of the tail was biflagellated as usual in trematodes. Unlike other platyhelminth spermatozoa, the sperm tail of Clonorchis sinensis showed the [9+2] pattern in the microtubular arrangement. The mitochondria with poorly developed cristae were observed throughout the middle piece. The middle piece of the tail showed dull ladder or triangular shapes with the two flagella at the bottom. But, the principal piece of the tail was slightly flattened cylindrical shape with two flagella within the cytoplasm. The end piece was uniflagellated. It was not clearly identified whether the end piece was subdivided into two by flagellum or the lengths of the two flagella were different. The glycogen granules were rich in the cytoplasm throughout the length of the spermatozoa. These granules might be the energy source for the movement of the spermatozoa.

Preparation and in vitro characteristics of polymerized pyridoxylated hemoglobin.

Stroma-free hemoglobin solutions have been the subject of extensive studies as potential acellular oxygen carriers. Oncotic pressure considerations limit the hemoglobin concentration of the solutions (6-8 g/dl) to one-half the normal whole blood values. Furthermore, the free hemoglobin has a short plasma half-life (2-4 hours). In principle, polymerization offers a means of normalizing the oxygen-carrying capacity as well as extending the plasma half-life. Pyridoxylation of hemoglobin prior to polymerization provides an acceptable P50. Pyridoxylated hemoglobin (14-16 g/dl) was polymerized with a 12.5 percent glutaraldehyde solution. Since the goal was to obtain a 15 g per dl solution iso-oncotic with plasma, the polymerization reaction was monitored by the drop in colloid osmotic pressure. The reaction was quenched with 1.3 M lysine when the colloid osmotic pressure reached normal values (20-25 torr). The polymerization yield was 80 percent, with molecular weights ranging from 120,000 to 600,000 Dalton. The polymerized hemoglobin had a binding coefficient of 1.32, a P50 of 16 torr, a Bohr coefficient of -0.12, and a Hill coefficient of 1.7. The viscosity of the solution was 4.5 centipoise. The methemoglobin levels were comparable to that of unpolymerized stroma-free hemoglobin. Polymerized hemoglobin solutions provide a normal oxygen-carrying capacity with a P50 comparable to that of unpolymerized stroma-free hemoglobin solutions.