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At least 991 records · Page 55Linked to original sources
PubMed1988

Influence of SLA haplotype on preimplantation embryonic cell number in miniature pigs.

Embryonic cell number in miniature pigs inbred for specific SLA haplotypes (a, c, and d) was determined on Day 6 by nuclear staining and, on Days 9 and 11, by DNA analyses (first day of oestrus = Day 0). Pigs exhibiting first behavioural oestrus at 08:00 h were hand-mated to an SLA homozygous boar 12 and 24 h later. Numbers of embryos flushed from uteri at 08:00-10:00 h on Days 6, 9 and 11 were greater (P less than 0.05) for SLAd females than for SLAa or SLAc females, which did not differ (8.2 vs 6.8 and 6.2, respectively). Recovery rates (embryos recovered/CL number) were similar, averaging 75.8% for all three SLA haplotypes. Embryos from SLAd dams contained fewer blastomeres (23 cells) on Day 6 than did embryos from SLAa (89 cells) or SLAc (79 cells) females. The reduced cell numbers of SLAd vs SLAa or SLAc embryos continued to Day 9 (28 vs 107 and 67 ng DNA/embryo) and Day 11 (167 vs 674 and 586 ng DNA/embryo). These results suggest an effect of the SLA complex on preimplantation embryonic development.

Animals↗
PubMed1994

Characterization of glycoconjugates in the endometrium of the miniature pig during different reproductive periods.

Lectin-binding glycoconjugates in the endometrium of miniature pigs were determined for sexually immature, dioestrus, oestrus and early pregnancy periods, using five horseradish peroxidase-labelled lectins. Apparent changes associated with sexual maturity were increases in binding intensity of wheat germ agglutinin (WGA), Glycine max agglutinin (SBA) and Ulex europaeus agglutinin (UEA) and the appearance of Ricinus communis agglutinin (RCA) binding. The binding intensity of WGA, SBA and UEA further increased at oestrus, particularly for UEA which showed a stage-specific binding on the surface of endometrial epithelium. Pregnancy-related changes included an increase in WGA binding and a decrease in UEA and RCA binding. The results indicate that stage-specific alterations in lectin binding glycoconjugates occur in the endometrium of pigs associated with sexual maturity and the reproductive cycle.

Animals↗
PubMed2006

Miniaturization applied to analysis of nucleic acids in heterogeneous tissues.

Despite huge efforts in sample analysis, the measurement of marker nucleic acids within tissues remains largely nonquantitative. Gene analyses have benefited from sensitivity gains through in vitro gene amplification, including PCR. However, whilst these processes are intrinsically suited to highly reproducible, accurate and precise gene measurement, the term semiquantitative analysis is still commonly used, suggesting that other fundamental limitations preclude a generic quantitative basis to gene analysis. The most poorly defined aspect of gene analysis relates to the sample itself. The amount of cells and, particularly, cell subtype composition are rarely annotated before analysis; indeed, they are often extrapolated after analysis. To advance our understanding of pathogenesis, assay formats will benefit from resembling the dimensions of the cell, to assist in the analysis of cellular components of tissue complexes. This review is partly a perspective on how current miniaturization technologies, in association with molecular biology, microfluidics and surface chemistries, may evolve from the parts of a paradigm to enable the unambiguous quantitative analysis of complex biologic matter.

Animals↗
PubMed2000

Acceptance reaction: intragraft events associated with tolerance to renal allografts in miniature swine.

Inbred miniature swine that are treated for 12 d with a high dose of cyclosporin A develop tolerance to MHC class II matched, class I-mismatched renal allografts. The aim of this study was to clarify the intrarenal allograft events associated with the development of tolerance in this protocol. Morphologic and immunologic studies were performed in serial biopsies from accepting grafts after 12 d of cyclosporin A treatment (n = 4) and were compared with those from untreated control rejecting grafts (n = 4). In accepting grafts with stable function, a transient interstitial infiltrate developed. The cellular infiltrate had many similarities to that in rejecting grafts; both had T cells and macrophages, similar proportions of T-cell subsets, and a similar frequency of in situ nick end labeling (TUNEL)+ apoptotic infiltrating cells. However, the cellular infiltrate in the acceptance reaction was distinguished by less T-cell activation (interleukin-2 receptor+), less proliferation (proliferating cell nuclear antigen+) of infiltrating cells, and less graft cell apoptosis in arteries, tubules, glomeruli, and peritubular capillaries. Thereafter, the infiltrate in the accepting grafts progressively resolved with decreased cell proliferation, activation, and apoptotic graft parenchymal cell injury, but the high frequency of apoptosis persisted in graft-infiltrating cells. In parallel to the intragraft events, donor-specific unresponsiveness developed as assessed by cell-mediated cytotoxicity by blood mononuclear cells in vitro. In conclusion, the acceptance reaction in transplanted grafts is characterized by progressive resolution of T-cell proliferation and activation and of cell-mediated graft injury, as well as prolonged T-cell apoptosis. These intragraft events suggest that both T-cell anergy and T-cell deletion occur in the graft during the development of tolerance. Some of the described immunopathologic findings (activation, proliferation, apoptosis) may be useful in distinguishing acceptance from rejection, as well as in predicting later graft acceptance in tolerance induction protocols.

Animals↗
PubMed1983

Chronic mucogingival defects in miniature swine.

Controversy surrounds the importance of keratinized gingiva in maintaining periodontal health. A well-defined animal model system is necessary to evaluate longitudinally the role of keratinized gingiva when plaque control is inadequate or where dental procedures (restorative, prosthetic or orthodontic) alter the periodontal environment. Facial gingiva was excised from eight primary incisors in miniature swine. Contralateral teeth were used as controls. The experimental teeth exhibited mucogingival defects at 3 and 6 month observation periods. The secondary teeth erupting into the experimental regions also exhibited recession and chronic mucogingival defects. The marginal tissue in regions devoid of keratinized gingiva demonstrated clinical signs of inflammation. No progressive gingival recession was present. Excision of keratinized gingiva to produce mucogingival defects in swine provides a convenient model system for evaluating the effect of dental procedures on periodontal health where little or no keratinized gingiva is present.

Animals↗
PubMed1983

Effect of inflammation on periodontal attachment levels in miniature swine with mucogingival defects.

Previous authors have postulated that a dense band of keratinized, attached gingiva prevents the spread of inflammation from the gingival margin to the subjacent attachment apparatus. Chronically inflamed mucogingival defects were created over the vestibular surface of 12 central incisors in miniature swine. The untreated contralateral incisors were identified as paired controls. Placement of horizontal reference notches on the tooth surfaces was followed by measurement of Probing Depth (PD) and Probing Attachment Level (PAL) on the vestibular aspect of each experimental and control tooth. No plaque removal was accomplished at any time during the study. One year following the attainment of baseline data, all measurements were repeated. Results show an increase in PD and a loss of PAL in both experimental and control regions. No difference in increase of PD or loss of PAL between the groups could be discerned.

Animals↗
PubMedDate not supplied

Meeting the problems of first-generation insulin infusion pumps: clinical trial of a new miniature infuser.

We designed and constructed a new miniature, open-loop insulin infusion pump specifically to overcome the problems of many first generation insulin infusers. Special features are small size, adjustable volumetric basal infusion rate, rapid electronically mediated prandial insulin boosts, facility for doubling and halving the basal infusion rate and/or prandial delivery, and alarms for low battery state, motor over-run, stoppage, and control circuit malfunction. The infuser takes a specially designed syringe prefilled with short-acting insulin, sufficient in most diabetic patients for at least 7 days treatment with 100 U/ml insulin. To test clinical efficacy nine insulin-dependent diabetic patients received continuous subcutaneous insulin infusion (CSII) with the new infuser for periods up to 6 mo. Four patients previously CSII-treated with a first-generation pump and five who were new to CSII achieved and maintained the expected degree of near-normoglycemia. There were no pump breakdowns and a questionnaire completed by patients during the study confirmed ease and simplicity of operation and an appreciation of the advantages of the new pump compared with one widely used first-generation infuser.

Adult↗
PubMed1995

Growth patterns in selected organs of the miniature swine as determined by gross macromolecular composition.

As part of a larger study designed to characterize the early developmental stages of the Hormel-Hanford strain miniature pig, the brain, kidney, liver, pancreas, and spleen from male animals were examined for changes in RNA, DNA, and protein contents from 1 to 196 d after birth. Distinct patterns were found for changes with age in macromolecular levels. Protein levels increased from d 1 to 56 in all organs except spleen, in which little change was noted. Gel electrophoresis showed little qualitative change in the liver protein profile during this period. A fat-free, non-nucleic acid, protein-containing fraction, insoluble in hot alkali, appeared in the brain after approximately 1 wk following birth. DNA concentrations decreased markedly from d 1 to d 196 for brain, kidney, and spleen but decreased more gradually for liver and pancreas. RNA levels declined slightly or remained the same in all organs except pancreas, where a large increase occurred from d 1 to weaning (56 d). Growth proceeded in all organs by increases in cell number (hyperplasia), as evidenced by increases in total (level or concentration x organ weight) DNA, or by hypertrophy, as evidenced by increases in the ratio of protein to DNA or by a combination of both processes. Hypertrophic growth was attained by d 56 and continued to sexual maturity in all organs except spleen. Hyperplastic growth continued to sexual maturity in all organs except brain.

Aging↗
PubMed2002

Technical note: adipose tissue blood flow in miniature swine (Sus scrofa) using the 133xenon washout technique.

The purpose of this study was to examine the 133xenon washout technique as a viable method for measuring adipose tissue blood flow (ATBF) in swine. Using a total of 32 female Yucatan miniature swine (Sus scrofa), the partition coefficient for 133xenon in swine subcutaneous adipose tissue was determined and ATBF was measured at rest and under various physiological conditions. These conditions included feeding, anesthesia, epinephrine infusion, and acute exercise. The effects of epinephrine and acute exercise were examined in both sedentary and exercise-trained swine. The partition coefficient value for 133xenon in swine subcutaneous adipose tissue was 9.23+/-0.26 mL/g (mean +/- SD, n = 10). The average value for resting ATBF in swine was 3.98+/-2.72 mL/(100 g tissue-min) (n = 19). Feeding increased ATBF by approximately fivefold over fasting values, and isoflurane anesthesia significantly decreased ATBF compared to rest (1.64+/-1.12 vs 3.92+/-4.22 mL/[100 g x min], n = 10). A 30-min epinephrine infusion (1 microg/[kg BW x min]) significantly increased ATBF from a resting value of 3.13+/-2.61 to 10.35+/-5.31 mL/(100 g x min) (n = 12). Epinephrine infusion into exercise-trained swine increased ATBF to the same extent as when infused into sedentary swine. An acute, 20-min bout of exercise significantly increased ATBF in swine, and the sedentary swine showed a larger increase in ATBF than their exercise-trained littermates relative to rest: 7.83 vs 2.98 mL/(100 g x min). In conclusion, the 133xenon washout technique appears to be a viable method for measuring ATBF in swine; our findings are comparable to swine ATBF values reported using the microsphere method and are consistent with values reported in animal and human studies.

Adipose Tissue↗
PubMed1996

Developmental-anatomical observations on cleavage line patterns of the skin in Chinese miniature pigs.

In twelve Chinese miniature pigs (CMP), of both sexes and ranging from newborn to 5 months of age, the postnatal developmental features of the cleavage lines of the skin of the whole body were examined by the stab-wound method, using a metal probe with a sharp conical point. 1). The CL patterns of the skin in the 5-month-old CMP were largely similar to those of adult Landrace-strain pigs (Wakuri et al., 1993). 2). At each monthly stage, the CL of the skin of the inter-ocular area, medial ocular angle, umbilicus, preputial orifice and anus presented a convergent arrangement. An annular pattern was found in the skin around the eye, the base of the ear, and the vulva. 3). Some alterations in CL patterns were seen during the general and regional growth of CMP, as shown in the skin of the lateral side of the trunk, the prepuce and the scrotum.

Abdomen↗
PubMedDate not supplied

HYOMEX: a miniature universal testing machine for in vivo biomechanical studies.

A miniaturized universal testing machine, HYOMEX, designed for biomechanically testing spinal structures of an anaesthetized research animal, such as a pig, is presented. A variety of mechanical applications such as static and dynamic tests, creep and relaxation tests, and fatigue tests with frequencies up to 20 Hz are possible. The system permits force control as well as displacement control. Continuous surveillance is made possible through interfacing the system to a computer. An application is presented where the viscoelastic behaviour in a porcine lumbar spine was measured.

Animals↗
PubMed1986

The role of the sympathetic nervous system in 2-kidney DOCA-hypertensive Yucatan miniature swine.

To assess the mechanism responsible for maintaining the elevated arterial pressure in 2-kidney DOCA treated Yucatan miniature swine, cardiovascular parameters and the responses to hexamethonium bromide (HMB) were evaluated in normal and DOCA treated animals. Using chronically instrumented conscious animals, measurements of mean arterial pressure (MAP), cardiac output (CO), and calculated total peripheral resistance (TPR) revealed that with DOCA hypertension MAP was increased 50-60 mmHg above controls. This increased pressure was due to an increase in TPR with CO remaining normal. HMB normalized the MAP of the DOCA animals via a selective lowering of TPR to a value similar to that of the controls. In DOCA hypertensive animals these functional changes, due to increased peripheral sympathetic nerve activity, were reflected by significantly elevated plasma norepinephrine. In this animal DOCA administration produces a neurogenic form of hypertension which appears to be analogous to essential hypertension in man.

Animals↗
PubMed2006

Image-guided system with miniature robot for precise positioning and targeting in keyhole neurosurgery.

This paper describes a novel image-guided system for precise automatic targeting in minimally invasive keyhole neurosurgery. The system consists of the MARS miniature robot fitted with a mechanical guide for needle, probe or catheter insertion. Intraoperatively, the robot is directly affixed to a head clamp or to the patient's skull. It automatically positions itself with respect to predefined targets in a preoperative CT/MRI image following an anatomical registration with an intraoperative 3D surface scan of the patient's facial features and registration jig. We present the system architecture, surgical protocol, custom hardware (targeting and registration jig), and software modules (preoperative planning, intraoperative execution, 3D surface scan processing, and three-way registration). We also describe a prototype implementation of the system and in vitro registration experiments. Our results indicate a system-wide target registration error of 1.7 mm (standard deviation = 0.7 mm), which is close to the required 1.0-1.5 mm clinical accuracy in many keyhole neurosurgical procedures.

Magnetic Resonance Imaging↗
PubMed1993

The effect of fracture on femoral head blood flow. Osteonecrosis and revascularization studied in miniature swine.

Miniature swine were used to study the effect of cervical fracture on femoral head blood flow. Laser Doppler flowmetry was used to evaluate femoral head blood flow before and after the fracture, after internal fixation with or without compression, and 8 weeks post-fracture. Fluorescent bone-labeling was performed at 2, 4 and 6 weeks post-fracture. Femoral head blood flow decreased to 40 percent of baseline following fracture, partly from the disruption of venous drainage. Histologically, all femoral heads showed some degree of trabecular thinning, microfracture, and neovascularization when compared with controls. Analyses of the laser Doppler flowmetry data, fluorescent label histology, microradiography and bone densitometry indicated that late (4-6 weeks) revascularization produces severe trabecular mechanical weakening and resultant femoral head collapse. Femoral head ischemia following fracture probably falls along a continuum, with only the more severe cases proceeding to mechanical collapse. Femoral neck fractures in the minipig produce femoral head necrosis of a severity and incidence which closely parallels that of the human population; thus, the minipig is a useful model for further study of complications following femoral neck fracture in humans.

Animals↗
PubMed1985

Adrenocortical function in deoxycorticosterone acetate (DOCA)-hypertensive Yucatan miniature swine.

Adrenocortical function was assessed in six normal and six chronic (greater than 12 weeks), DOCA-hypertensive Yucatan miniature swine; mean arterial pressures were 115.3 +/- 11.7 and 163.6 +/- 27.2 mm Hg, respectively (mean +/- SEM). Adrenocortical function was evaluated in vivo by measuring changes in plasma cortisol and aldosterone in response to exogenous ACTH (0.25 mg, iv), and in vitro by measuring the responses of collagenase-isolated adrenocortical cells to ACTH and angiotensin II. Corticoids were measured by specific radioimmunoassay. Basal plasma cortisol values of conscious DOCA-hypertensive swine were approximately 53% of the values of normotensive swine (P less than 0.05). However, ACTH induced a 419% increase in plasma cortisol values in DOCA-hypertensive swine compared to a 261% increase in the normotensive swine (P less than 0.05). These differences between the two groups were not altered by anesthesia. There were no significant differences in ACTH-induced changes in plasma aldosterone between the normotensive and DOCA-hypertensive swine. Experiments in vitro showed that the corticoid secretory responses of adrenocortical cells from DOCA-hypertensive animals were 6 times more sensitive to ACTH and 3.2 times more sensitive to angiotensin II than those of cells from normotensive swine. Thus, despite the possibility of adrenocortical insufficiency due to suppressed plasma renin activity and the negative feedback of DOCA on the hypothalamic-hypophyseal-adrenal axis, adrenocortical function of DOCA-hypertensive swine was hyperresponsive to trophic hormones. Results from this study suggest that the DOCA-hypertensive swine may be a valuable model in elucidating the relationship between hypertension and adrenocortical function and in investigating nonclassical control of the adrenal cortex, that is, control exerted during the hypertensive state that exists apart from or in addition to that exerted by ACTH and angiotensin II.

8-Bromo Cyclic Adenosine Monophosphate↗
PubMed1991

Acute renal function in chronically sympathectomized deoxycorticosterone acetate-treated miniature swine.

We recently validated a swine model in which chronic treatment with 6-hydroxydopamine (6-OHDA) produced an effective sympathectomy. These sympathectomized swine demonstrated a significantly attenuated hypertensive response when treated with deoxycorticosterone acetate (DOCA). Because renal nerve activity is elevated and important in controlling renal function and blood pressure in the DOCA swine model, we wanted to study the effect of chronic sympathectomy on acute renal hemodynamics and tubular function. Kidney function was assessed in 14 DOCA-treated miniature swine, 8 of which were sympathectomized by chronic treatment with 6-OHDA, while 6 served as controls. Effective renal sympathectomy in this model has been previously confirmed by a significant reduction (97%) of norepinephrine in renal cortical tissue. When anesthetized, mean arterial pressure and renal blood flow were similar between the two groups. Glomerular filtration rate was lower by 43%, urine flow rate by 71%, sodium excretion by 66%, and potassium excretion by 48% in the 6-OHDA DOCA animals. All of these parameters were significantly different from the intact DOCA controls. These results indicate that anesthetized, chronically sympathectomized swine exhibit decreased renal excretory function. The changes in renal function may have been due to the development of a tubular or glomerular supersensitivity to circulating antinatriuretic factors, since the 6-OHDA group had a 28% greater pressor response to the alpha-agonist phenylephrine and a significantly greater fall in mean arterial pressure in response to alpha-blockade with prazosin when compared with the controls. These changes in renal function may also explain why the 6-OHDA animals demonstrated a slight increase in mean arterial pressure in response to DOCA. Because acute renal denervation in DOCA-treated swine produces a diuresis and natriuresis, this study affirms that there may be important functional differences in acutely versus chronically denervated kidneys for which the implications under normal physiologic conditions are unknown.

Animals↗
PubMed2004

Miniature ultrasonic probes for diagnosis and treatment of digestive tract diseases.

AIM: To investigate the clinical value of miniature ultrasonic probes (MUPs) for the diagnosis and treatment of digestive tract diseases. METHODS: Endoscopic ultrasonography (EUS) was performed for patients with its indications with 7.5-20 MHz MUPs and double-cavity electronic endoscope. According to the diagnosis of MUPs, patients who had indications of treatment received endoscopic resection or surgical excision. Postoperative histological results were compared with the preoperative diagnosis of MUPs. A few patients without endoscopic resection or surgical excision were periodically followed up with MUPs. RESULTS: A total of 537 patients were examined by MUPs, of them, 256 were diagnosed with gastrointestinal submucosal lesions, 146 with pseudo-submucosal lesions, 50 with digestive tract cancers, 17 with peptic ulcer, 11 with cholecystolithiasis, 8 with chronic pancreatitis, and 2 with achalasia and 47 were diagnosed as normal. After MUPs examinations, 220 patients received endoscopic resection or surgical excision, and the postoperative histological results of 211 patients were completely consistent with the preoperative diagnosis of MUPs. The diagnostic accuracy of MUPs was 95.9%. The result of follow-up with MUPs indicated that gastrointestinal leiomyoma, lipoma, phlebangioma and cyst were unchanged within 1-2 years. The patients who received endoscopic resection or centesis did not have any complications. CONCLUSION: MUPs are of value in diagnosing gastrointestinal submucosal lesions, staging of digestive tract cancers and biliary-pancreatic diseases. They play a very important role in making therapeutic plans.

Adenoma↗
PubMed1998

Miniaturization of medical products: the development challenge.

The growing generation of miniaturized medical devices requires developers to re-evaluate their design processes. New products must take account of a non-technical user base, large production volumes, shorter product lifetimes and pressure to reduce production and purchasing costs. This article looks at some of the strategies design and development teams can adopt to meet those challenges.

Electric Countershock↗