Expression of receptor beta-chain variable region by T cells in human periodontal disease

T cells play a major part in the immune response in periodontal diseases. In order to determine any selective T-cell receptor (TCR) beta-chain variable region (V beta) usage in the infiltrates of healthy/ gingivitis (H/G) and adult periodontitis (AP), cells were extracted from gingival biopsies, the CD4 and CD8 cells stained with antibodies to eight V beta regions, and two-colour flow cytometry used to analyse the data. The frequencies of CD4 and CD8 cells expressing each of the TCR-V beta families varied from 0 to 46% between individuals. A high percentage of CD4 and CD8 cells expressed the V beta 13 family in several AP biopsies, but, in a number of H/G tissues, a high percentage of T cells expressed up to three families including the V beta 13 region, these varying from individual to individual. The mean results showed a significantly greater percentage of V beta 5.2-3-positive CD4 cells (p = 0.003) and V beta 5.1- and 5.2-3-positive CD8 cells (p = 0.003 and 0.025, respectively) isolated from H/G than AP tissues. The percentage of V beta 3.1-positive CD4 cells extracted from H/G tissues was also higher but not quite significant at the 0.05 level (p = 0.051). Sections of gingival tissue in biopsies from H/G and AP were stained in situ; there were no significant differences in the mean expression of V beta 3.1-, 5.1- or 5.2-3-positive cells. A second aim was to determine the effect of Porphyromonas gingivalis on the TCR repertoire. There were no differences in the mean percentage of CD4 or CD8 cells expressing the eight TCR-V beta regions between the two groups after stimulation in vitro with P. gingivalis outer-membrane antigens. There was, however, a trend towards a decrease in the percentage of positive CD4 and CD8 T cells after culture with the antigen. This was significant for CD4 cells from H/G expressing the V beta 5.1 and 5.3 TCRs (p = 0.032 and p = 0.038, respectively). This trend was not evident for V beta 5.2-3-positive CD4 cells or V beta 5.1-positive CD8 cells isolated from both H/G and AP nor for V beta 3.1-positive CD8 cells from AP. The results show that there may be restricted V beta usage in gingival tissues, particularly in H/G tissues. The V beta 5 and 3.1 families may be selected for in the gingival tissues and may also be involved in P. gingivalis activation.

[A study on low grade malignant tumors arisen in the trachea and the bronchus]

Twelve patients who suffered from low grade malignant tumors arisen in the trachea and the bronchus (6 of carcinoid, 4 of mucoepidermoid carcinoma, and 2 of adenoid cystic carcinoma) underwent surgical treatment from 1977 to 1996 in our department. Operations included 1 sleeve resection of the trachea, 1 patch plasty of the trachea, 3 sleeve lobectomies, and 7 lobectomies. Lymph node dissection was performed in 9 of 12 cases. Metastases in lymph nodes were not found in all 12 cases. Five year survival rate of low grade malignant tumors arisen in the trachea and the bronchus was 78.8% and better than that of stage I lung cancers.

Ganglioneuroma of left adrenal gland in a patient with Turner syndrome during growth hormone therapy

We report on a Japanese girl with Turner syndrome (45,XO) who developed ganglioneuroma of the left adrenal gland during growth hormone (GH) therapy. She had received GH replacement therapy from the age of 6.8 years. At the age of 10.3 years, abdominal ultrasonography revealed a mass which occupied the upper area of her left kidney. Computed tomography and magnetic resonance imaging of the abdomen showed a low density mass with a smooth surface located between the upper portion of the left renal vein and the pancreas. Microscopic examination resulted in a diagnosis of ganglioneuroma of the left adrenal gland. At present we cannot conclude that patients who have received GH replacement therapy are at higher risk for developing tumors compared to those without GH replacement therapy.

Cytokine messenger RNA expression in chronic inflammatory periodontal disease

It has previously been reported that, in periodontitis lesions, T cells with a memory/activated phenotype and with a type 2 cytokine profile accumulate in an oligoclonal fashion. Delineation of the role of cytokines in periodontal inflammation has, however, been complicated because of cross-regulation and because of their overlapping and often redundant effects. The aim of this study was to examine messenger RNA levels for interferon gamma, interleukin 4 (IL-4), IL-10, IL-12 and IL-13 in gingival tissues and peripheral blood mononuclear cells of patients with adult periodontitis. Reverse transcription polymerase chain reaction and subsequent image analysis was used to determine the level of mRNA for each cytokine. The mean expression of interferon gamma mRNA was significantly higher in peripheral blood mononuclear cells than in gingival tissues. In contrast, the mean expression of IL-10 mRNA was higher in gingival tissues than in peripheral blood mononuclear cells. This high expression of IL-10 mRNA was, in fact, seen in only 7 gingival tissue samples with the majority of samples showing levels similar to peripheral blood mononuclear cells. There was no difference in the mean expression of IL-12 p35 mRNA between gingival tissues and peripheral blood mononuclear cells. However, IL-12 p40 mRNA was expressed higher in gingival tissues than in peripheral blood mononuclear cells in 6 out of 16 samples with significant difference of mean expression. Like IL-10, gingival tissue samples and peripheral blood mononuclear cells expressed similar levels of IL-12 p40 mRNA. There was no difference in the mean expression of IL-13 in gingival tissues and peripheral blood mononuclear cells. Nevertheless, more peripheral blood mononuclear cell samples demonstrated high IL-13 mRNA expression than gingival tissue samples. IL-4 mRNA was weak but detectable in 3 gingival tissue samples. These results support the concept that cytokines form complex networks in periodontitis lesions and that their overlapping and redundant effects should be taken into account when considering the pathology of inflammatory periodontal disease. Dichotomous expression of IL-10 and IL-12 p40 mRNA in the periodontal lesion may be associated with disease entity.

Interfollicular fibroblasts in the human thyroid gland: recognition of a CD34 positive stromal cell network communicated by gap junctions and terminated by autonomic nerve endings

While epithelial structure and functions have been substantially investigated in many organs, the mesenchymal elements have received less attention. Compared with follicular epithelial cells, there are a few morphological studies on the stroma of human thyroid gland. In order to characterize more fully and assess its possible functions, 15 samples of surgical and autopsy human thyroid tissue were studied by classical histology, immunohistochemistry, transmission electron microscopy, electron microscopic immunohistochemistry, and scanning electron microscopy. In human thyroid gland, the interfollicular connective tissue surrounding the follicles contained collagenous matrix, fibroblasts, unmyelinated nerve fibers with Schwann cells, small blood vessels, lymphatics, lymphocytes, plasma cells, macrophages, and mast cells. At the ultrastructural level, gap junctions between the cytoplasmic processes of interfollicular fibroblasts constituted a novel observation. Immunohistochemistry using a monoclonal antibody against Cx43 confirmed the distribution of gap junctions between stromal fibroblastic cells, which was compatible with the ultrastructural findings. The frequent and intimate association of fibroblastic processes with nerve terminals was also shown. Interfollicular stromal fibroblasts also stained with CD34. The main constituent of the human thyroid stromal tissue was a CD34 positive reticular network involving fibroblasts, mononuclear cells and nerve terminals. It represents a highly ordered stroma, with potential structural and functional similarities to the stroma of bone marrow (Yamazaki and Allen, 1990).

Nonoxidative ethanol and methanol changes in the heart and brain tissue of alcohol abusers

Fatty acid ethylesters (FAEE) are synthesized from ethanol and fatty acids in the heart and brain. Similarly fatty acid methylesters (FAME) are synthesized from methanol and fatty acids. Whereas methanol reportedly indicates recent or chronic consumption of alcoholic beverages, an elevated serum methanol concentration (SMC) indicates mainly chronic alcohol intake. We compared levels of FAEE and FAME in cardiac and brain tissues with the blood ethanol concentration(BEC) and SMC in 18 alcohol abusers and 29 control subjects without history of alcohol abuse(control) to clarify the relationships between BEC and FAEE levels and that between SMC and FAME levels. We also assessed the possibilities of discriminating the alcohol abusers from the control group and of detecting FAEE and FAME accumulations in cardiac and brain tissues. Levels of FAEE and FAME were determined by gas chromatography (GC) in autopsied cardiac and brain tissues. Heart FAEE (HFAEE) levels correlated with BEC (r = 0.61) and it was possible to distinguish between alcohol abusers and controls using discriminant analysis. HFAEE levels in the alcohol abusing group were elevated even with low BEC. Therefore, HFAEE levels indicate ethanol accumulation in cardiac tissues of alcohol abusers. Brain FAEE (BFAEE) and heart and brain FAME (HFAME and BFAME) levels did not correlated closely with BEC and SMC, respectively. However, there are some possible means of discriminating between the two groups in terms of BEC and BFAEE, and SMC and FAME respectively, using discriminant analysis. Employing this analysis, the rate of misclassification was 17-25.5%. The mean levels of HFAEE, BFAEE, HFAME and BFAME were higher in the alcohol abusing group than in the control group, even when their BEC and SMC were quite low.

Immunohistochemical and ultrastructural investigation of the human vestibular dark cell area: roles of subepithelial capillaries and T lymphocyte-melanophage interaction in an immune surveillance system

BACKGROUND

The aim of the present study was to morphologically characterize the structure of the subepithelial blood vessels in the dark cell area of the human vestibular organs, and to determine whether immunocompetent cells such as macrophages and lymphocytes could be found around these small blood vessels.

MATERIALS AND METHODS

All 31 surgical specimens (semicircular canals and utricles) were obtained from patients with vestibular schwannoma. Formalin fixed specimens were stained with hematoxylin and eosin (H&E), and with antibodies to von Willebrand Factor (vWF), leukocyte common antigen (LCA), and UCHL-1, and were examined with light microscope. Specimens fixed with glutaraldehyde were examined with a transmission electron microscope (TEM).

OBJECTIVES

Subepithelial blood vessels stained positive for vWF. By TEM observation, these blood vessels were observed to be capillaries that consisted of non-fenestrated endothelium, occasional pericytes, and a basement membrane. They were usually accompanied by melanophages with a number of secondary lysosomes containing phagocytosed degraded melanosomes and lipid droplets. Moreover, melanocytes and their cell processes directly surrounded these subepithelial capillaries. The fact that cells which were positively stained with LCA and UCHL-1 were present both in the intra- and subepithelial layer of the specimens, and that by TEM the intra- and subepithelial mononuclear cells with a lymphoid appearance had clustered dense bodies in their cytoplasm, suggested that they were a population of T lymphocytes.

CONCLUSIONS

Results suggested the possibility of a T lymphocyte-melanophage (macrophage) interaction, both originating from and harbored around subepithelial capillaries, which suggests the presence of an immune surveillance system in the human vestibular organs.

Concentration of catecholamines and indoleamines in the cerebrospinal fluid of patients with vascular parkinsonism compared to Parkinson's disease patients

The concentration of catecholamines and indoleamines in the cerebrospinal fluid of patients with vascular parkinsonism (VP) was compared to that in patients with Parkinson's disease (PD) and controls. Compared to the controls, the concentration of tyrosine was significantly higher, and the concentration of L-dopa and 3-O-methyldopa (3-OMD) was significantly lower in both VP and PD patients. The balance between the 3-OMD/L-dopa and dopamine (DA)/L-dopa ratios was changed in favor of 3-OMD/L-dopa in both VP patients and PD patients suggesting the preservation of a compensatory mechanism. All these changes were less marked in VP patients than in PD patients. A remarkable finding was that in contrast to PD patients the concentration of DA and norepinephrine (NE) was significantly higher in VP patients than in the controls. The decrease in the concentration of 5-hydroxytryptamine (5-HT) was significantly greater in VP patients than in PD patients. In PD patients, the concentration of DA, NE, and 5-HT showed significant correlation with the severity of motor symptoms. In VP patients, the concentration of 5-HT alone showed significant correlation with the severity of motor symptoms and cognitive dysfunction. These findings suggest that VP patients may have similar disturbances in the DA synthesis pathway as PD patients, but differ from PD patients in that the concentrations of DA and NE are elevated and the decrease in the 5-HT concentration is greater in VP patients.

The cool seal system: a practical solution to the shaft seal problem and heat related complications with implantable rotary blood pumps

A critical issue facing the development of an implantable, rotary blood pump is the maintenance of an effective seal at the rotating shaft. Mechanical seals are the most versatile type of seal in wide industrial applications. However, in a rotary blood pump, typical seal life is much shorter than required for chronic support. Seal failure is related to adhesion and aggregation of heat denatured blood proteins that diffuse into the lubricating film between seal faces. Among the blood proteins, fibrinogen plays an important role due to its strong propensity for adhesion and low transition temperature (approximately 50 degrees C). Once exposed to temperature exceeding 50 degrees C, fibrinogen molecules fuse together by multi-attachment between heat denatured D-domains. This quasi-polymerized fibrin increases the frictional heat, which proliferates the process into seal failure. If the temperature of the seal faces is maintained well below 50 degrees C, a mechanical seal would not fail in blood. Based on this "Cool-Seal" concept, we developed a miniature mechanical seal made of highly thermally conductive material (SiC), combined with a recirculating purge system. A large supply of purge fluid is recirculated behind the seal face to augment convective heat transfer to maintain the seal temperature below 40 degrees C. It also cools all heat generating pump parts (motor coil, bearing, seal). The purge consumption has been optimized to virtually nil (< 0.5 cc/day). An ultrafiltration unit integrated in the recirculating purge system continuously purifies and sterilizes the purge fluid for more than 5 months without filter change. The seal system has now been incorporated into our intraventricular axial flow blood pump (IVAP) and newly designed centrifugal pump. Ongoing in vivo evaluation of these systems has demonstrated good seal integrity for more than 160 days. The Cool-Seal system can be applied to any type of rotary blood pump (axial, diagonal, centrifugal, etc.) and offers a practical solution to the shaft seal problem and heat related complications, which currently limit the use of implantable rotary blood pumps.

Long-term animal experiments with an intraventricular axial flow blood pump

A miniature intraventricular axial flow blood pump (IVAP) is undergoing in vivo evaluation in calves. The IVAP system consists of a miniature (phi 13.9 mm) axial flow pump that resides within the left ventricular (LV) chamber and a brushless DC motor. The pump is fabricated from titanium alloy, and the pump weight is 170 g. It produces a flow rate of over 5 L/min against 100 mmHg pressure at 9,000 rpm with an 8 W total power consumption. The maximum total efficiency exceeds 17%. A purged lip seal system is used in prototype no. 8, and a newly developed "Cool-Seal" (a low temperature mechanical seal) is used in prototype no. 9. In the Cool-Seal system, a large amount of purge flow is introduced behind the seal faces to augment convective heat transfer, keeping the seal face temperature at a low level for prevention of heat denaturation of blood proteins. The Cool-Seal system consumes < 10 cc purge fluid per day and has greatly extended seal life. The pumps were implanted in three calves (26, 30, and 168 days of support). The pump was inserted through a left thoracotomy at the fifth intercostal space. Two pursestring sutures were placed on the LV apex, and the apex was cored with a myocardial punch. The pump was inserted into the LV with the outlet cannula smoothly passing through the aortic valve without any difficulty. Only 5 min elapsed between the time of chest opening and initiation of pumping. Pump function remained stable throughout in all experiments. No cardiac arrhythmias were detected, even at treadmill exercise tests. The plasma free hemoglobin level remained in the acceptable range. Post mortem examination did not reveal any interference between the pump and the mitral apparatus. No major thromboembolism was detected in the vital organs in Cases 1 or 2, but a few small renal infarcts were detected in Case 3.

An implantable centrifugal blood pump for long term circulatory support

A compact centrifugal blood pump was developed as an implantable left ventricular assist system. The impeller diameter is 40 mm and the pump dimensions are 55 x 64 mm. This first prototype was fabricated from titanium alloy, resulting in a pump weight of 400 g including a brushless DC motor. Weight of the second prototype pump was reduced to 280 g. The entire blood contacting surface is coated with diamond like carbon to improve blood compatibility. Flow rates of over 7 L/min against 100 mmHg pressure at 2,500 rpm with 9 W total power consumption have been measured. A newly designed mechanical seal with a recirculating purge system ("Cool-Seal") is used as a shaft seal. In this seal system, seal temperature is kept under 40 degrees C to prevent heat denaturation of blood proteins. Purge fluid also cools the pump motor coil and journal bearing. The purge fluid is continuously purified and sterilized by an ultrafiltration filter incorporated into the paracorporeal drive console. In vitro experiments with bovine blood demonstrated an acceptably low hemolysis rate (normalized index of hemolysis = 0.005 +/- 0.002 g/100 L). In vivo experiments are currently ongoing using calves. Via left thoracotomy, left ventricular apex-descending aorta bypass was performed utilizing a PTFE (Polytetrafluoroethylene) vascular graft, with the pump placed in the left thoracic cavity. In two in vivo experiments, pump flow rate was maintained at 5-8 L/min, and pump power consumption remained stable at 9-10 W. All plasma free hemoglobin levels were measured at < 15 mg/dl. The seal system has demonstrated good seal capability with negligible purge fluid consumption (< 0.5 ml/ day). Both animals remain under observation after 162 and 91 days of continuous pump function.

Influence of sporulation medium and divalent ions on the heat resistance of Alicyclobacillus acidoterrestris spores

The influence of divalent cations on the heat resistance of spores of the thermoacidophilic spoilage bacterium Alicyclobacillus acidoterrestris was studied. The heat resistance of A. acidoterrestris spores was not affected by the presence of the different divalent cations (Ca2+, Mg2+, Ba2+, Mn2+ and Sr2+) in the sporulation medium, and by the demineralization or remineralization. And the Ca and Mn contents in A. acidoterrestris spores were scarcely changed by these treatments. However, the heat resistance of Bacillus subtilis spores was affected with the changes of Ca content in the spores. The Ca contents in A. acidoterrestris spores of the different forms were greater than the DPA content. In contrast, the DPA content in the B. subtilis spores was greater than the Ca content. These findings suggest that the presence of constant amount of Ca-DPA and a stronger binding characteristic of divalent ions, especially Ca and Mn, is reflected in the specific heat resistance of A. acidoterrestris spores.

Bone density and body composition in Japanese women

Total body bone mineral content (BMCTB in g) and density (BMDTB in g/cm2) and body composition were measured in 1006 healthy Japanese women aged 20-79 years using dual X-ray absorptiometry. Peak BMDTB was 1.11 +/- 0.05 g/cm2 in women 20-49 years, and mean BMDTB was 1. 019 g/cm2 in the 6th decade, 0.956 g/cm2 in the 7th decade, and 0. 900 g/cm2 in the 8th decade. BMDTB declined by 0.007 g/cm2/year in women after age 50. This age-related decline in BMD showed a similar pattern to that seen for the lumbar spine and femoral neck, but the actual rate of loss was lower for BMDTB than for these other measurement sites. There was no significant difference between a eumenorrheic premenopausal group and a group with irregular menses. BMCTB and BMDTB were associated with body build, lean tissue mass, and fat mass (r = 0.29 approximately 0.65 and 0.26 approximately 0.41, respectively). Bone mass and density decreased significantly in older women of all body builds. Premenopausal Japanese women had a 5% lower BMDTB than U.S. and European whites, but the difference was several times greater in postmenopausal than in premenopausal women.

[Usefulness of particle size distribution analyzer for counting the number of sperm]

We tried to use particle size distribution analyzer to count the number of sperm. The epididymis was removed from male Syrian golden hamsters intratracheally instilled with indium arsenide, indium phosphide or phosphate buffer only, and the homogenate of the cauda epididymidis was used as the sperm sample. The number of sperm counted with particle size distribution analyzer correlated well with the number of sperm counted with hemocytometer (r = 0.96) and the coefficient of the regression line was almost 1. When the same sperm sample was counted repetitively (n = 4), there was no difference in the coefficient of variation between the sperm number counted with particle size distribution analyzer and the sperm number counted with hemocytometer (6.4 +/- 5.8% vs. 7.8 +/- 4.0%). From these results, particle size distribution analyzer was thought to be useful for counting the number of sperm.

Expression of basic fibroblast growth factor (FGF-2)-associated with tumour proliferation in human pancreatic carcinoma

Basic fibroblast growth factor (FGF-2) is one of the mitogens that facilitate epithelial proliferation and angiogenesis. We analysed the expression of FGF-2 and type I fibroblast growth factor receptor (FGFR1) in 20 selected cases of human pancreatic carcinoma (PC) in connection with proliferation of tumour cells and intratumour endothelial cells (ECs), using immunohistochemistry and in situ hybridization (ISH). By FGF-2 immunostaining, tumour cells were strongly positive in 10 cases (50%). By FGFR1 immunostaining, stromal fibroblasts and ECs occasionally showed positive staining. Tumour cells in 12 cases (60%) were strongly positive. Expression of FGF-2 mRNA, as examined by ISH, was detected in 12 cases (60%) of PC, and its distribution pattern was similar to that of FGF-2 immunostaining. We divided these cases into two groups according to the result of FGF-2 immunostaining, and examined the Ki67 labelling indices of tumour cells and ECs between these two groups. These two proliferative indices were significantly higher in FGF-2-positive than in FGF-2-negative cases (P<0.05, P<0.05, respectively). These findings suggest that the expression of FGF-2 in PC is strongly associated with the proliferation of tumour cells and ECs and its increased expression may give tumour a growth advantage.

Subcutaneous fat distribution of the abdomen and buttocks in Japanese women aged 20 to 58 years

Subcutaneous fat is an essential element in shaping the body of human beings. In this research, skinfold thickness was measured specifically in 33 regions of the human body, including the abdomen and buttocks. Based on our measurements, the subcutaneous fat distribution was assessed for several age groups. The subjects were healthy Japanese women aged 20 to 58 years. Skinfold thickness was measured using the B-mode ultrasound methods, together with anthropometric measurement. A comparison was made between the following five age groups: early 20's, late 20's, 30's, 40's and 50's. The measured values for the early 20's group were used as the standard and the relationship between increase ratio of subcutaneous fat and age was studied. Through our research, we obtained data on the subcutaneous fat distribution in each age group. The largest change was observed between the ages of the early 20's and late 20's. The skinfold thickness measurements of the abdomen and buttocks was consistently around 10 mm for the early 20's, and increased up to 23.8 mm on the rear side section for the late 20's. This result indicates that the increase ratio varied depending on the part of body. Furthermore, the changes in skinfold thickness were different in specific parts of the abdomen and buttocks among different age groups. The difference in skinfold thickness between upper and lower sections of the abdomen also becomes more pronounced with age. Skinfold thickness increased significantly between the early 20's and late 20's. Among the body regions, measurements at the rear side showed the largest change with age; averaging 11.3 mm for the early 20's compared to 33.6 mm for the 50's. The subcutaneous fat distribution on the buttock also showed the differences with age, indicating changes in body shape. Using careful measurements of the abdomen and buttocks, subcutaneous fat distribution among each age group was determined as well as the variation in changes with the aging process.

[Early repair of ventricular septal rupture in patients over 80 years of age: infarction exclusion technique]

Since 1994, three patients more than 80 years of age underwent early repair of ventricular septal rupture complicating acute myocardial infarction at our hospital. The infarction exclusion technique introduced by David and Komeda was employed. Average aortic clamp time, cardiopulmonary bypass time and operation time were 83 minutes, 129 minutes and 228 minutes, respectively. No hemostatic suture were required to the left ventricular suture line. All patients survived. One patient with posterior ventricular septal rupture had residual shunt and necessitated transient hemodialysis but recovered. Thus, the infarction exclusion technique seems to be useful in the elderly with unfavorable tissue fragility.

Eighteen cases exposed to sarin in Matsumoto, Japan

Forty-six patients who were exposed to sarin consulted our hospital because of darkness of vision, and ocular pain, vomiting, dyspnea and headaches on June 27 and 28, 1994. Eighteen patients were admitted and 4 of them were in the critical state. There were 6 features: 1) depression of plasma cholinesterase activity (17 of 18 patients, 94%), 2) hypokalemia (4/18, 22%), 3) depression of triglyceride (12/18, 67%), 4) hypocapnia (5/17, 29%), 5) partial pressure of oxygen (PaO2) <80 mmHg, or requirement of O2 inhalation (15/18, 83%), 6) white blood cells (WBC) >9,000 per mm3 (13/18, 72%). Seventeen patients were discharged from hospital, but one patient is still suffering from akinetic mutism after two years.

In vivo evaluation of an extracorporeal pediatric centrifugal blood pump

This paper summarizes the authors' in vivo experience in evaluating a miniature centrifugal blood pump designed for pediatric/neonatal ventricular support. Left ventricular bypass was accomplished in two adult sheep and five juvenile lambs (5.5-80.0 kg) via either central (left ventricle to carotid artery) or peripheral (jugular vein to carotid artery) cannulation. Animals were weaned from mechanical ventilation and continuously monitored. Hemodynamic parameters remained within a normal range over the duration of the bypass. Two of five lambs were electively killed at 8, and 76 hours; the remaining three lambs died from respiratory complications at 33, 44, and 156 hours. There were no mechanical complications, and blood seal integrity was confirmed beyond 6 days. The pump speed was maintained at 3,000-4,500 rpm with pump flow rates between 0.4-1.5 L/min. Average plasma free hemoglobin was below 20 mg/dl in the five lamb experiments. Renal, hepatic, and hematologic indices also remained within physiologic ranges. Histopathologic analyses of major organs revealed renal cortical infarctions in two of five lambs. Examination of the pump surfaces after explant indicated small areas of thrombus in the housing adjacent to the outflow ports in two experiments. These encouraging results support further testing and refinement of this miniature centrifugal pump.

Survival for up to six months in calves supported with an implantable axial flow ventricular assist device

This paper summarizes the authors' in vivo experience to date with an implantable axial flow blood pump designed for long-term ventricular support. This small, valveless pump with blood-lubricated bearings has been implanted in six calves (83 +/- 6 kg) as a left ventricular assist device (LVAS). The left ventricle and descending thoracic aorta were cannulated by left thoracotomy, and the pump was placed in a subcutaneous pocket below the costal margin. Animals remained hemodynamically stable throughout the course of support during partial left ventricular bypass. Five animals were killed after 15, 27, 52, 57, and 181 days. The longest survivor (181 days) demonstrated normal pump function at the time death. Pump speed was maintained at 10,100 +/- 100 rpm, with an average pump flow rate of 4.9 +/- 0.5 L/min under resting physiologic conditions. Average plasma free hemoglobin was 17.4 +/- 7.5 mg/dl. Renal, hepatic, and hematologic indices remained within physiologic range in all of these animals, except during the immediate postoperative period. Histopathologic analyses of major organs after death revealed small renal cortical infarcts in five of six animals; the remaining organs were normal. These animal studies support the feasibility of this small implanted axial flow pump for long-term ventricular assistance.