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PubMed2003

Miniature vibrating flow blood pump using a cross-slider mechanism for external shunt catheter.

The prototype of the miniature vibrating flow pump (VFP) is developed for the external shunt catheter. The cross-slider mechanism is applied to vibrate the tube, which causes the pumping effect. This mechanism results in successful development of the miniature and lightweight VFP. By the use of the prototype VFP, the experiment of the basic pump performance is made in detail based on the authorized procedure in the research field of fluids engineering. The typical H-Q curve of VFP, which is the relationship between the pump head and the flow rate, can be obtained. This result suggests that the miniature VFP developed here can be expected to be used as the booster pump for the external shunt catheter in clinical applications.

Arteriovenous Shunt, Surgical↗
PubMed1998

Comparison of the merits of measuring equine chorionic gonadotrophin (eCG) and blood and faecal concentrations of oestrone sulphate for determining the pregnancy status of miniature horses.

The relative merits of measuring blood concentrations of equine chorionic gonadotrophin (eCG, previously known as pregnant mare serum gonadotrophin (PMSG)), or oestrone sulphate (OS), or faecal OS concentrations for determining pregnancy status in miniature horses were investigated. Pregnant mares between 40 and 140 days after mating had serum eCG concentrations > 1 I.U. mL-1, with the highest concentrations occurring between days 50 and 120. However, eCG measurements were susceptible to returning a 'false positive' diagnosis of pregnancy. Plasma OS concentrations ranged from 0.1 to 3.6 ng mL-1 in non-pregnant mares, whereas pregnant mares beyond 100 days post-mating all had plasma OS concentrations > 30 ng mL-1. Faecal OS concentrations ranged from 4 to 89 ng g-1 in non-pregnant mares. For faecal samples collected from pregnant mares 150 days or more after mating, 97% of samples had OS concentrations > 85 ng g-1, the value 3 standard deviations above the mean non-pregnant value. None had values below 67 ng g-1, the value 2 standard deviations above the mean non-pregnant value. These results show that measurement of eCG is suitable for determining pregnancy status in miniature mares between 40 and 100 days post-mating. However, mares returning a 'pregnant' diagnosis should undergo a blood OS test 100 or more days after mating to eliminate the possibility of a 'false positive' diagnosis. Measuring blood OS is recommended as the method of choice for determining pregnancy status in miniature mares 100 or more days after mating. Faecal OS measurements provide a non-invasive alternative to blood OS testing from 150 days post-mating. However, the discrimination between 'pregnant' and 'non-pregnant' levels of OS is not as great in faeces as it is in blood.

Animals↗
PubMed1993

Comparative evaluation of the Rapid ID 32A kit system, miniaturized standard procedure and a rapid fermentation procedure for the identification of anaerobic bacteria.

The RAPID ID 32A and a rapid fermentation procedure were compared with a miniaturized standard procedure for the identification of 102 isolates of anaerobic bacteria belonging to 11 genera. The miniaturized standard procedure identified all 102 isolates at the genus level and 90 at the species level. The rapid fermentation procedure failed to identify 12 and 24 isolates at the genus and species levels respectively and is unsatisfactory. The RAPID ID 32A system misidentified 4 isolates (4%) at the genus level, 3 of which could have been avoided if the results of the Gram stain, the fundamental procedure in medical microbiology, had been taken into account. The system correctly identified 89 isolates at the species level. Since it does not produce species identifications within the genera Mobiluncus and Veillonella of which 7 and 2 isolates respectively were included in the study, the percentage of correct identifications at the species level is 96.7% (90/93). The RAPID ID 32A system is about 25 times more expensive than the miniaturized standard procedure if the investment for a gas chromatograph is not taken into account.

Bacteria, Anaerobic↗
PubMed2005

Social capital, the miniaturization of community and high alcohol consumption: a population-based study.

AIMS: To study the impact of social participation, trust, and the miniaturization of community, i.e. high social participation/low trust, on the risk of high alcohol consumption. METHODS: The Scania 2000 public health survey is a cross-sectional, postal questionnaire study. A total of 13 604 persons aged 18-80 years were included. A logistic regression model was used to investigate the association between the social capital variables and high alcohol consumption (168.0 g/week or more for men and 108.0 g/week or more for women). The multivariate analyses analysed the importance of confounders (age, country of origin, education, and economic stress) on the risk of high alcohol consumption according to the social capital variables. RESULTS: A 14.0% proportion of all men and 7.8% of all women had an alcohol consumption above recommended levels. High alcohol consumption above recommended levels was not associated with social participation but negatively associated with trust among men. The miniaturization of community category, i.e. high social participation/low trust, had significantly higher risks of high alcohol consumption compared to the high social capital (high social participation/high trust) category among men. CONCLUSION: High social participation combined with low trust, i.e. the miniaturization of community, is positively associated high alcohol consumption among men. A structural/social factor which may affect the amount of alcohol consumed has thus been identified in this study.

Adolescent↗
PubMed2004

Social capital, the miniaturization of community and cannabis smoking among young adults.

OBJECTIVES: The impact of social participation, trust and the miniaturization of community, i.e. the combination of high social participation and low trust, on cannabis smoking was investigated. METHODS: The 2000 public health survey in Scania is a cross-sectional study. A total of 13,715 persons aged 18-80 years, of which 3,978 persons aged 18-34 years were included in this study, answered a postal questionnaire, which represents 59% of the random sample. A logistic regression model was used to investigate the association between the social capital variables and ever having experienced cannabis smoking. The multivariate analysis was performed to investigate the importance of possible confounders (age, country of origin and education) on the differences in having experienced cannabis smoking according to social participation, trust and their four combination categories. RESULTS: Cannabis smoking is not associated with social participation, but positively associated with low trust among both men and women, and the miniaturization of community, i.e. the combination of high social participation and low trust, among men. CONCLUSIONS: This study suggests that the miniaturization of community, i.e. the combination of high social participation and low levels of generalized trust of other people, may enhance the experience of cannabis smoking.

Adolescent↗
PubMed2005

Miniature RT-PCR system for diagnosis of RNA-based viruses.

This paper presents an innovative portable chip-based RT-PCR system for amplification of specific nucleic acid and detection of RNA-based viruses. The miniature RT-PCR chip is fabricated using MEMS (Micro-electro-mechanical-system) techniques, and comprises a micro temperature control module and a PDMS (polydimethylsiloxane)-based microfluidic control module. The heating and sensing elements of temperature control module are both made of platinum and are located within the reaction chambers in order to generate a rapid and uniform thermal cycling. The microfluidic control module is capable of automating testing process with minimum human intervention. In this paper, the proposed miniature RT-PCR system is used to amplify and detect two RNA-based viruses, namely dengue virus type-2 and enterovirus 71 (EV 71). The experimental data confirm the ability of the system to perform a two-step RT-PCR process. The developed miniature system provides a crucial tool for the diagnosis of RNA-based viruses.

Dengue Virus↗
PubMed2001

Repigmentation after autologous miniature punch grafting in segmental vitiligo in North Indian patients.

Segmental vitiligo is rather refractory to medical treatment. The paucity of literature on the results of autologous miniature punch grafting in segmental vitiligo in dark-skinned patients led us to conduct such a study in 15 dark-skinned patients of North Indian origin to observe the repigmentation response to this technique at different sites. The age range was 16-42 years (mean 23.08 years). There were four males and eleven females (M:F ratio being 1:2.75) who had the disease for 3-15 years. After autologous miniature punch grafting, a remarkable repigmentation was obtained in 12 (80%) cases with 90% to 100% improvement. About 40-60% repigmentation was observed within 3-6 months in the majority (66.6%) of cases and near total to total repigmentation was observed within 2 years. The maximum pigment spread was observed over the face (cheeks) and neck, and the minimum pigment spread was observed over the left arm and right upper eyelid. Complications were minimal. The present study demonstrates that autologous miniature punch grafting is a safe and easy technique, that produces good cosmetic results in the unsightly depigmenting lesions of segmental vitiligo, especially on the face and exposed areas, even in dark-skinned races if patients are selected carefully. This can be of great benefit to patients who are psychologically disturbed by their disease.

Adolescent↗
PubMed1994

Initial clinical experience with a miniature biplane transesophageal echocardiographic probe in adults.

Transesophageal echocardiography (TEE) is now routinely used in cardiovascular medicine. With improved technology the size of TEE probes has increased. Recently there has been interest in using smaller probes for adult TEE. We used a miniature 32-element, phased array biplane probe in 20 consecutive adults who underwent clinically indicated TEE evaluation. The miniature biplane probe was easily inserted without complication in all patients including one with thrombocytopenia and one with an esophageal stricture. Subjectively the probe was easier to insert and better tolerated by patients than standard adult TEE probes. High quality images of near-, mid-, and far-field structures were obtained in a majority of patients. Color Doppler identified mitral regurgitation in 12 (60%) patients, tricuspid regurgitation in ten (50%) patients, and aortic insufficiency in five (25%) patients. The miniature biplane TEE probe used in this study enhanced patient comfort without significant loss of image quality.

Adult↗
PubMed2000

Congenital portosystemic shunts in toy and miniature poodles.

Three male Poodles (two Toy, one Miniature) were presented to their veterinarians for evaluation of urolithiasis and varying degrees of hepatic encephalopathy. All three dogs were diagnosed as having intrahepatic shunts and referred for surgical correction. In each case, shunts arose from the right branch of the portal vein and were amenable to perivascular dissection caudal to where the vessel entered the hepatic parenchyma and to placement of perivascular cellophane bands to achieve shunt attenuation. During the same period, a female Miniature Poodle also presented for treatment of a congenital portosystemic shunt discovered during evaluation for generalised motor seizures. This animal had an extrahepatic portoazygous shunt that was completely ligated. Congenital portosystemic shunts have not previously been identified in Toy and Miniature Poodles at the University Veterinary Centre, Sydney and the anatomical types of shunt seen in this breed have not previously been reported in a consecutive series of cases. The three male dogs are noteworthy for a number of reasons: all had intrahepatic shunts, despite being small breed dogs; all three presented in a similar fashion, and all had shunts of an anatomical type amenable to placement of cellophane bands. One male dog died within 12 hours of surgery, the remaining three dogs survived and their liver function was normal at follow-up between 2 and 3 months after surgery. Use of cellophane bands for successful attenuation of intrahepatic shunts has not been previously reported.

Animals↗
PubMedDate not supplied

Ultracentrifugal and electrophoretic characteristics of the plasma lipoproteins of miniature schnauzer dogs with idiopathic hyperlipoproteinemia.

To better characterize the idiopathic hyperlipoproteinemia of Miniature Schnauzer dogs, the plasma lipoproteins of 20 Miniature Schnauzers (MS) and 11 dogs of other breeds (DOB) were evaluated by ultracentrifugation, electrophoresis, and biochemical tests. Seventeen MS were healthy; 3 had diabetes mellitus. Plasma from 6 of 17 healthy and all 3 diabetic MS was visibly lipemic. Lipemia was slight to marked in healthy lipemic MS, and marked in diabetic ones. All DOB had clear plasma; 8 were healthy and 3 had diabetes. All healthy lipemic MS and diabetic lipemic MS had hypertriglyceridemia associated with excess very low density lipoproteins. Chylomicronemia was present in 4 of 6 healthy lipemic MS and all 3 diabetic lipemic MS. Lipoproteins with ultracentrifugal and electrophoretic characteristics of normal low density lipoprotein were lacking in 4 of 6 healthy lipemic MS. The lipoprotein patterns of 4 of 11 healthy nonlipemic MS were characterized by mild hypertriglyceridemia associated with increased very low density lipoproteins and a lack of lipoproteins with characteristics of normal low density lipoproteins. Lipoprotein patterns of diabetic DOB closely resembled those of healthy DOB; those of diabetic lipemic MS resembled those of markedly lipemic healthy lipemic MS. In conclusion, the hyperlipoproteinemia of Miniature Schnauzers is characterized by increased very low density lipoproteins with or without accompanying chylomicronemia; some affected dogs may have decreased low density lipoproteins.

Animals↗
PubMed1972

Pancreatic acinar cells: measurement of membrane potential and miniature depolarization potentials.

1. Intracellular recordings of membrane potentials have been made in vitro from the exocrine acinar cells of the mouse pancreas using glass micro-electrodes.2. The mean membrane potential of the acinar cells was -41.2 mV. Spontaneous miniature depolarization potentials of 0.5-5.0 mV amplitude and occurring at random intervals were often observed superimposed upon the resting membrane potential. Atropine 2.8 x 10(-6)M decreased, and physostigmine 1.23 x 10(-5)M increased, the frequency and amplitude of the miniature potentials.3. Electrical stimulation of the pancreatic nerves depolarized the acinar cells. Acetyl beta-methylcholine 10(-6)M produced a sustained depolarization. Atropine 1.4 x 10(-6)M blocked the depolarization to both electrical stimulation and acetyl beta-methylcholine.4. Pancreozymin depolarized the exocrine acinar cells but secretin did not.5. These results suggest that the miniature depolarization potentials are of cholinergic origin and that depolarization of the pancreatic exocrine cells by nerve stimulation or pancreozymin may trigger secretion.

Animals↗
PubMed2006

Differences between the scaling of miniature IPSCs and EPSCs recorded in the dendrites of CA1 mouse pyramidal neurons.

Anatomical studies have described inhibitory synaptic contacts on apical dendrites, and an abundant number of GABAergic synapses on the somata and proximal dendrites of CA1 pyramidal cells of the hippocampus. The number of inhibitory contacts decreases dramatically with distance from the soma, but the local electrophysiological characterization of these synapses at their site of origin in the dendrites is missing. We directly recorded dendritic GABA receptor-mediated inhibitory synaptic events in adult mouse hippocampal CA1 pyramidal neurons and compared them to excitatory synaptic currents recorded at the same sites. Miniature GABAergic events were evoked using localized application of a hyperosmotic solution to the apical dendrites in the vicinity of the dendritic whole-cell recording pipette. Glutamatergic synaptic events were blocked by kynurenic acid, leaving picrotoxin-sensitive IPSCs. We measured the amplitude and kinetic properties of mIPSCs at the soma and at three different dendritic locations. The amplitude of mIPSCs recorded at the various sites was similar along the somato-dendritic axis. The rise- and decay-times of local mIPSCs were also independent of the location of the synapses. The frequency of mIPSCs was 5 Hz at the soma, in contrast to < 0.5 Hz at dendritic sites, which could be increased to 10-20 Hz and 6-10 Hz, respectively, by our hyperosmotic stimulation protocol. Miniature glutamatergic events were evoked with the same protocol after blocking inhibitory synapses by bicucculine. The measured amplitudes increased along the somato-dendritic axis proportionally with their distance from the soma. The measured kinetic properties were independent of location. Consistent with the idea that IPSCs may have a restricted local effect in the dendrites, our data show a lack of distance-dependent scaling of miniature inhibitory synaptic events, in contrast to the scaling of excitatory events recorded at the same sites.

Animals↗
PubMed2002

Evaluation of a miniature electromagnetic position tracker.

The advent of miniaturized electromagnetic digitizers opens a variety of potential clinical applications for computer aided interventions using flexible instruments; endoscopes or catheters can easily be tracked within the body. With respect to the new applications, the systematic distortions induced by various materials such as closed metallic loops, wire guides, catheters, and ultrasound scan heads were systematically evaluated in this paper for a new commercial tracking system. We employed the electromagnetic tracking system Aurora (Mednetix/CH, NDI/Can); data were acquired using the serial port of a PC running SuSE Linux 7.1 (SuSE, Gmbh, Nürnberg). Objects introduced into the digitizer volume included wire loops of different diameters, wire guides, optical tracking tools, an ultrasonic (US) scan head, an endoscope with radial ultrasound scan head and various other objects used in operating rooms and interventional suites. Beyond this, we determined the influence of a C-arm fluoroscopy unit. To quantify the reliability of the system, the miniaturized sensor was mounted on a nonmetallic measurement rack while the transmitter was fixed at three different distances within the digitizer range. The tracker was shown to be more sensitive to distortions caused by materials close to the emitter (average distortion error 13.6 mm +/- 16.6 mm for wire loops positioned at a distance between 100 mm and 200 mm from the emitter). Distortions caused by materials near the sensor (distances smaller than 100 mm) are small (typical error 2.2 mm +/- 1.9 mm). The C-arm fluoroscopy unit caused considerable distortions and limits the reliability of the tracker (distortion error 18.6 mm +/- 24.9 mm). Distortions resulting from the US scan head are high at distances smaller than about 100 mm from the emitter. The distortions also increase when the scan head is positioned horizontally and close to the sensor (average error 4.1 mm +/- 1.5 mm when the scan head is positioned within a distance of 100 mm from the sensor). The distortions are slightly higher when the ultrasound machine is switched on. We also evaluated the influence of common medical instruments on distance measurements. For these measurements the average deviation from the known distance of 200 mm amounted to 3.0 mm +/- 1.5 mm (undistorted distance measurement 1.5 mm +/- 0.3 mm). The deviations also depend on the relative orientation between emitter and sensor. The results demonstrate that the miniature tracking system opens up new perspectives with regard to surgery applications where a flexible instrument is to be tracked within the body. Significant distortions caused by metallic objects only occur in the worst cases, for example, in the presence of a closed, unisiolated wire loop or a C-arm fluorescence unit close to the emitter and which can be avoided by suitable usage.

Calibration↗
PubMed2006

A miniaturized adaptive microphone array under directional constraint utilizing aggregated microphones.

This paper introduces a miniaturized microphone array using the Directionally Constrained Minimization of Power (DCMP) method, which utilizes the transfer functions of microphones located at the same place, namely aggregated microphones. The phased microphone array realizes a noise reduction and direction of arrival (DOA) estimation system according to differences in the arrival time, phase shift, and/or the level of the sound wave for each microphone. Hence it is difficult to miniaturize the microphone array. The objective of our research is to miniaturize the system size using aggregated microphones. In this paper, we first show that the phased microphone array system and the proposed aggregated microphone system can be described within the same framework. We then apply a microphone array under directional constraint to the aggregated microphones and compare the proposed method with the microphone array. We show the directional pattern of the aggregated microphones. We also show the experimental results regarding DOA estimation.

Journal Article↗
PubMed2002

AMPA receptor-mediated miniature synaptic calcium transients in GluR2 null mice.

AMPA-type glutamate receptors are normally Ca(2+) impermeable due to the expression of the GluR2 receptor subunit. By using GluR2 null mice we were able to detect miniature synaptic Ca(2+) transients (MSCTs) associated with AMPA-type receptor-mediated miniature synaptic currents at single synapses in primary cortical cultures. MSCTs and associated Ca(2+) transients were monitored under conditions that isolated responses mediated by AMPA or N-methyl-D-aspartate (NMDA) receptors. As expected, addition of the antagonist 6-cyano-7-nitroquinoxalene-2,3-dione (CNQX, 3 microM) blocked the AMPA receptor-mediated MSCTs. Voltage-gated Ca(2+) channels did not contribute to AMPA MSCTs because CdCl(2) (0.1-0.2 mM) did not significantly alter the frequency or the amplitude of the MSCTs. The amplitude of AMPA MSCTs appeared to be regulated independently from event frequency since the two measures were not correlated (R = 0.023). Synapses were identified that only expressed MSCTs attributed to either NMDA or AMPA receptors. At synapses with only NMDA responses, MSCT amplitude was significantly lower (by 40%) than synapses expressing both NMDA and AMPA responses. At synapses that showed MSCTs mediated by both AMPA and NMDA receptors, the amplitude of the transients in each condition was positively correlated (R = 0.94). Our results suggest that when AMPA and NMDA receptors are co-expressed at synapses, mechanisms exist to ensure proportional scaling of each receptor type that are distinct from the presynaptic factors controlling the frequency of miniature release.

6-Cyano-7-nitroquinoxaline-2,3-dione↗
PubMed2003

Laparoscopy-assisted intrapelvic sonography with a high-frequency, real-time miniature transducer to assess the ovary: a preliminary report.

OBJECTIVE: Our purpose was to evaluate the normal and pathologic internal textures of the ovary using laparoscopy-assisted intrapelvic sonography (LAIPS) with a specially developed 20-MHz flexible catheter-based high-resolution real-time miniature (2.4 mm in outer diameter) ultrasound transducer in patients with gynecologic disorders and infertile women. METHODS: 30 women (19 patients with gynecologic disorders and normal menstrual cycles (2 adenomyoses, 1 cervical cancer, 5 fibromyomas, 5 simple ovarian cysts, 1 endometriosis, 3 benign cystic teratomas, and 2 endometriomas), and 11 patients with infertility including 4 with polycystic ovarian syndrome, PCOS) were studied by intrapelvic sonography using a high-frequency real-time miniature transducer with pelvic saline effusion and laparoscopy. RESULTS: In the normal ovary in the mid-follicular phase, follicles were depicted more distinctly than with transvaginal sonography (TVS). In the late-follicular phase, cumulus oophorus formations were visualized in 6 of 9 patients (54.5%), but were not clear using TVS. In the luteal phase, the corpus luteum was noted in 9 of 12 patients (75%) by both TVS and LAIPS. In patients with PCOS, the thickened capsule of the ovary was distinguished clearly especially in the peripheral type, in which numerous small cysts were aligned in the subcapsular region of the ovary, whereas it could not be detected by TVS. In all 4 cases with PCOS (8 ovaries), the ovarian capsular thickness could be measured by means of LAIPS. In subjects with benign cystic teratoma, minimal high echoic lesions were depicted. In subjects with endometrioma, a diffuse coarse-granular internal texture was visualized. However, depiction of internal structures in large pathologic ovarian lesions was markedly limited because of the shallow scanning range of the high-frequency transducer. CONCLUSION: LAIPS with a high-frequency real-time miniature transducer might be a useful diagnostic modality to evaluate the normal physiologic textures of the ovary, as well as those with PCOS.

Adult↗
PubMed1994

Identification of coronary artery stenoses and poststenotic blood flow patterns using a miniature high-frequency epicardial transducer.

BACKGROUND: Intraoperative epicardial coronary Doppler ultrasound has the potential to provide anatomic and functional information. This technique has been hindered by the large size of standard transducers, but a miniature transducer is available that may fulfill the potential of coronary ultrasound. METHODS AND RESULTS: Twenty consecutive patients who were undergoing coronary artery bypass grafting were studied and compared with 9 control patients with normal coronary arteries who were undergoing routine mitral valve surgery. A miniature 6.5-MHz transducer was used to image coronary arteries and measure coronary blood flow velocities. Seventeen proximal left anterior descending and 3 right coronary artery stenoses were studied. As defined by coronary angiography (1 to 34 days before surgery), there were 13 severe stenoses (> 70%), 4 moderate stenoses (40% to 70%), 2 minor stenoses (< 40%), and 1 subtotal occlusion. Stenoses were readily identified by ultrasound. Color flow mapping demonstrated laminar flow in normal arteries and nonlaminar flow across moderate and severe stenoses. In the control patients with unobstructed arteries, peak and mean diastolic velocities were 35 +/- 2.1 and 26 +/- 1.9 cm/s with peak and mean systolic velocities of 16 +/- 1.4 and 11 +/- 0.8 cm/s, respectively. Prestenotic flow velocities were not significantly different from normal control values, but a wide range of poststenotic flow disturbances were detected. Analysis of the 20 study patients did not reveal significant differences in poststenotic compared with prestenotic flow. A subgroup analysis of 12 patients with severe left anterior descending coronary artery stenoses was performed, and reversed poststenotic systolic flow was seen in 9. Prestenotic peak and mean systolic velocities were 16.5 +/- 1.7 and 11.9 +/- 1.1 cm/s, respectively, and were significantly altered downstream of the stenoses at -22.7 +/- 17.2 and -15.9 +/- 10.9 cm/s (P < .05 and P < .01, respectively). Reversed systolic flow was seen only distal to severe left anterior descending coronary artery stenoses and did not correlate with retrograde collateral filling as determined by preoperative coronary angiography. Moderate stenoses appeared to increase both systolic and diastolic components of poststenotic flow. CONCLUSIONS: Epicardial Doppler ultrasound with a miniature transducer identifies coronary stenoses and associated blood flow disturbances. Compared with moderate lesions, severe stenoses demonstrated different poststenotic flow patterns. Intraoperative use of this technique may determine the hemodynamic significance of coronary stenoses.

Adult↗
PubMed2006

Differential mitochondrial DNA and gene expression in inherited retinal dysplasia in miniature Schnauzer dogs.

PURPOSE: To investigate the molecular basis of inherited retinal dysplasia in miniature Schnauzers. METHODS: Retina and retinal pigment epithelial tissues were collected from canine subjects at the age of 3 weeks. Total RNA isolated from these tissues was reverse transcribed to make representative cDNA pools that were compared for differences in gene expression by using a subtractive hybridization technique referred to as representational difference analysis (RDA). Expression differences identified by RDA were confirmed and quantified by real-time reverse-transcription PCR. Mitochondrial morphology from leukocytes and skeletal muscle of normal and affected miniature Schnauzers was examined by transmission electron microscopy. RESULTS: RDA screening of retinal pigment epithelial cDNA identified differences in mRNA transcript coding for two mitochondrial (mt) proteins--cytochrome oxidase subunit 1 and NADH dehydrogenase subunit 6--in affected dogs. Contrary to expectations, these identified sequences did not contain mutations. Based on the implication of mt-DNA-encoded proteins by the RDA experiments we used real-time PCR to compare the relative amounts of mt-DNA template in white blood cells from normal and affected dogs. White blood cells of affected dogs contained less than 30% of the normal amount of two specific mtDNA sequences, compared with the content of the nuclear-encoded glyceraldehyde-3-phosphate dehydrogenase (GA-3-PDH) reference gene. Retina and RPE tissue from affected dogs had reduced mRNA transcript levels for the two mitochondrial genes detected in the RDA experiment. Transcript levels for another mtDNA-encoded gene as well as the nuclear-encoded mitochondrial Tfam transcription factor were reduced in these tissues in affected dogs. Mitochondria from affected dogs were reduced in number and size and were unusually electron dense. CONCLUSIONS: Reduced levels of nuclear and mitochondrial transcripts in the retina and RPE of miniature Schnauzers affected with retinal dysplasia suggest that the pathogenesis of the disorder may arise from a lowered energy supply to the retina and RPE.

Animals↗