Biomedical subjects

N Yoshimura

Publications and source records attributed to N Yoshimura.

At least 55 records · Page 3Linked to original sources

PubMed2001

Neural control of the urethra.

Coordination between the urinary bladder and the urethra is mediated by multiple reflex pathways organized in the brain and spinal cord. Some reflexes promote urine storage; whereas other reflexes facilitate voiding. During bladder filling, activation of mechanoreceptor afferent nerves in the bladder wall triggers firing in the cholinergic efferent pathways to the external urethral sphincter (EUS) and in sympathetic adrenergic pathways to the urethral smooth muscle. These storage reflexes are dependent upon interneuronal circuitry in the spinal cord. During voiding the spinal storage reflexes are inhibited by supraspinal mechanisms which originate in the pontine micturition center. Glutamatergic, serotonergic and alpha, adrenergic excitatory transmission as well as GABAergic/glycinergic inhibitory transmission have been implicated in the central control of sphincter reflexes. During voiding, a parasympathetic nitrergic inhibitory input to the urethral smooth is activated. This reflex mechanism which is triggered by bladder afferents persists in paraplegic rats and therefore must be mediated at least in part by spinal interneuronal circuitry. In female rats, the parasympathetic nitrergic pathway is prominent; but in male rats it is obscured by a dominant parasympathetic cholinergic excitatory input to the urethral smooth muscle. The function of the cholinergic pathway in voiding is uncertain. Stimulation of urethral afferents can also influence bladder activity. Contraction of the external urethral sphincter activates afferents that inhibit reflex bladder contractions; whereas infusion of fluid through the urethra facilitates bladder contractions. These reflexes are also organized in the spinal cord and presumably play a role in urine storage and elimination. Alterations in primitive bladder-to-urethra and urethra-to-bladder reflex mechanisms may contribute to neurogenic bladder dysfunction.

Afferent Pathways↗

PubMed2001

Autologous primary muscle-derived cells transfer into the lower urinary tract.

The goal of these experiments was to establish the basic methodology for future clinical applications of muscle-derived cells (MDC) tissue engineering and gene transfer for the treatment of urological dysfunction. Primary MDC isolated via preplating techniques from adult female SD rats were transduced with retrovirus encoding the expression of beta-galactosidase reporter gene. The MDC were injected into the right and left lateral walls of the bladder and proximal urethra of the autologous animals (n = 6) with a 10 microl Hamilton micro syringe. The amount of injected MDC ranged from 1 to 2 x 10(6) cells. The injected tissue was harvested after 7, 14, and 28 days, sectioned and examined histologically for beta-galactosidase and immunohistochemically for fast myosin heavy chain specific to skeletal muscle. The tissues were also stained for anti-CD4 and anti-CD8 antibodies to assess for cellular immune reaction. We have detected a large number of autologous MDC expressing beta-galactosidase and positively stained for fast myosin heavy chain in the bladder and urethral wall. Many injected myoblasts and myotubes were also seen in the bladder and urethral wall at each time point. Staining of lymphocytes with anti-CD4 and anti-CD8 antibodies was negative after MDC injection at each time point. We have demonstrated the long-term survival of autologous MDC and MDC mediated gene transfer into the bladder and urethral wall. Autologous MDC and MDC mediated gene transfer may be a promising treatment to augment bladder and urethral sphincter function.

Animals↗

PubMed2001

Gene therapy and tissue engineering for urologic dysfunction: status and prospects.

This article reviews the recent advances in gene therapy and tissue engineering for urologic dysfunction. Although the number of gene therapy-based clinical trials has increased dramatically in the field of urologic oncology, such trials are still few within the neurourologic field. Recently, new biologic approaches employing growth factors have been utilized to treat various pathological conditions. Among them, transfer of genes such as those encoding growth factors represents a promising way to deliver therapeutic proteins to malfunctioning tissues, which leads to the improvement of organ function. Tissue engineering, which may eventually be combined with gene therapy, also offers the potential to create new functional genitourinary tissue for regeneration and replacement of tissue lost as a consequence of disease. Thus, both tissue engineering and gene therapy may hold promising new solutions in the urologic field.

Animals↗

PubMed2001

Nitric oxide synthase gene therapy for erectile dysfunction: comparison of plasmid, adenovirus, and adenovirus-transduced myoblast vectors.

BACKGROUND AND PURPOSE: Nitric oxide (NO) has been recognized as an important transmitter for genitourinary tract function. This transmitter mediates smooth muscle relaxation and is essential for erection. The objective of our research was to determine whether overexpression of nitric oxide synthase (NOS) in the corpus cavernosum of the penis would correct erectile dysfunction. MATERIALS AND METHODS: We introduced the inducible form of the enzyme NOS (iNOS) into the corpus cavernosum of adult (250-300 g) male Sprague-Dawley rats by injecting a solution of plasmid, adenovirus, or adenovirus-transduced myoblast cells (adeno-myoblast) (N = 3-5 each group). We also injected plasmid, adenovirus, and adeno-myoblast encoding the expression of the beta-gatactosidase reporter gene. RESULTS: We noted expression of beta-galactosidase throughout the corpora cavernosum after injection of each of the three solutions. Staining was greatest for adeno-myoblast followed by adenovirus and then plasmid. The basal intracavernous pressure (ICP) of iNOS-treated animals (adenovirus and adenovirus-transduced myoblast) increased to 55 +/- 23 cm H(2)O v 5 +/- 6 H(2)O in naive animals (P = 0.001). Stimulation of the cavernous nerve (15 Hz, 1.5 msec, 10-40 V, 1 min) resulted in a twofold increase in ICP (adenovirus and adeno-myoblast) from the basal level of the iNOS-treated animals. Direct in situ measurement of NO demonstrated release of 1 to 1.3 microM NO in the adeno-myoblast-treated penis. CONCLUSION: Myoblast-mediated gene therapy was more successful in delivering iNOS into the corpus cavernosum than were the direct adenovirus or plasmid transfection methods. Gene therapy of NOS may open new avenues of treatment for erectile dysfunction. Control of NOS expression would be necessary to prevent priapism.

Adenoviridae↗

PubMed2001

Persistence and survival of autologous muscle derived cells versus bovine collagen as potential treatment of stress urinary incontinence.

PURPOSE: We explored the use of autologous muscle derived cells as a method of treating stress urinary incontinence. We determined whether urethral muscle derived cell injection is feasible and compared it with bovine collagen injection. MATERIALS AND METHODS: Muscle derived cells isolated from female Sprague-Dawley rats were first transduced with retrovirus carrying the transgene for beta-galactosidase. We injected approximately 1 to 1.5 x 106 cells into the bladder wall and proximal urethra of 6 autologous animals. Tissue was harvested after 3 and 30 days, sectioned, stained for fast myosin heavy chain and assayed for beta-galactosidase. To compare muscle derived cell and bovine collagen injections 100 microl. of commercially available bovine collagen were also injected in Sprague-Dawley female rats. Tissue was harvested in 3 animals each after 3 and 30 days, sectioned and stained for trichrome. Subsequently, 3 adult SCID mice were used to compare the level of transgene expression at each time point after injecting 1.5 x 106 cells per injection, which were transduced with adenovirus carrying the transgene for beta-galactosidase. RESULTS: A large number of cells expressing beta-galactosidase were observed in the bladder and urethral wall 3 and 30 days after autologous cell injection in Sprague-Dawley rats. The persistence of primary muscle derived cells at 3 days was similar to that of collagen. However, at 30 days there was significant cell persistence while only a minimal amount of injected bovine collagen was detectable. Approximately 88% of the beta-galactosidase expression at day 3 remained at day 30 in SCID mice. CONCLUSIONS: We present 2 new findings important for the emerging field of urological tissue engineering, including the feasibility of injecting autologous skeletal muscle derived cells into the lower urinary tract and the greater persistence of such injected cells versus injected bovine collagen. Therefore, autologous muscle derived cell injection may be an attractive alternative treatment option for stress urinary incontinence.

Animals↗

PubMed2001

Predicting visual outcome after macular hole surgery using scanning laser ophthalmoscope microperimetry.

AIMS: To determine if postoperative visual outcome after successful macular hole surgery can be predicted with preoperative scanning laser ophthalmoscope (SLO) microperimetry. METHODS: A prospective non-comparative study of 16 eyes in 15 patients examined before the surgery. RESULTS: Visual outcome following macular hole surgery correlated with the "maximum parahole sensitivity", the highest intensity of stimulus to which the patient did not respond to any of the stimuli around the hole. Preoperative visual acuity, duration of the symptoms, size of the macular hole, and the "minimum parahole sensitivity", the lowest intensity to which the patient responded to all the stimuli around the hole, did not correlate significantly with postoperative visual acuity. CONCLUSION: Preoperative assessment of patients using SLO microperimetry is a good predictor of visual outcome after macular hole surgery.

Aged↗

PubMed2001

Pharmacology of the lower urinary tract.

The functions of the lower urinary tract, to store and periodically release urine, are dependent on the activity of smooth and striated muscles in the urinary bladder, urethra, and external urethral sphincter. This activity is in turn controlled by neural circuits in the brain, spinal cord, and peripheral ganglia. Various neurotransmitters, including acetylcholine, norepinephrine, dopamine, serotonin, excitatory and inhibitory amino acids, adenosine triphosphate, nitric oxide, and neuropeptides, have been implicated in the neural regulation of the lower urinary tract. Injuries or diseases of the nervous system, as well as drugs and disorders of the peripheral organs, can produce voiding dysfunctions such as urinary frequency, urgency, and incontinence or inefficient voiding and urinary retention. This chapter will review recent advances in our understanding of the pathophysiology of voiding disorders and the targets for drug therapy.

Animals↗

PubMed2001

Analysis of the afferent limb of the vesicovascular reflex using neurotoxins, resiniferatoxin and capsaicin.

The afferent limb of the vesicovascular reflex (VV-R) evoked by distension or contraction of the urinary bladder (UB) was studied in urethane-anesthetized female rats by examining the changes in VV-R after administration of C-fiber afferent neurotoxins [capsaicin and resiniferatoxin (RTX)]. Systemic arterial blood pressure increased parallel (5.1 to 53.7 mmHg) with graded increases in UB pressure (20 to 80 cm H(2)O) or during UB contractions. The arterial pressor response to UB distension was significantly reduced (60-85%) by acute or chronic (4 days earlier) intravesical administration of RTX (100-1,000 nM) or by capsaicin (125 mg/kg sc) pretreatment (4 days earlier). Chronic neurotoxin treatments also increased the volume threshold (>100%) for eliciting micturition in anesthetized rats but did not change voiding pressure. Acute RTX treatment (10-50 nM) did not alter the arterial pressor response during reflex UB contractions, whereas higher concentrations of RTX (100-1,000 nM) blocked reflex bladder contractions. It is concluded that VV-R is triggered primarily by distension- and contraction-sensitive C-fiber afferents located, respectively, near the luminal surface and deeper in the muscle layers of the bladder.

Administration, Intravesical↗

PubMed2001

Nitric oxide modulates Ca(2+) channels in dorsal root ganglion neurons innervating rat urinary bladder.

The effect of a nitric oxide (NO) donor on high-voltage-activated Ca(2+) channel currents (I(Ca)) was examined using the whole cell patch-clamp technique in L(6)-S(1) dorsal root ganglion (DRG) neurons innervating the urinary bladder. The neurons were labeled by axonal transport of a fluorescent dye, Fast Blue, injected into the bladder wall. Approximately 70% of bladder afferent neurons exhibited tetrodotoxin (TTX)-resistant action potentials (APs), and 93% of these neurons were sensitive to capsaicin, while the remaining neurons had TTX-sensitive spikes and were insensitive to capsaicin. The peak current density of nimodipine-sensitive L-type Ca(2+) channels activated by depolarizing pulses (0 mV) from a holding potential of -60 mV was greater in bladder afferent neurons with TTX-resistant APs (39.2 pA/pF) than in bladder afferent neurons with TTX-sensitive APs (28.9 pA/pF), while the current density of omega-conotoxin GVIA-sensitive N-type Ca(2+) channels was similar (43-45 pA/pF) in both types of neurons. In both types of neurons, the NO donor, S-nitroso-N-acetylpenicillamine (SNAP) (500 microM), reversibly reduced (23.4-26.6%) the amplitude of I(Ca) elicited by depolarizing pulses to 0 mV from a holding potential of -60 mV. SNAP-induced inhibition of I(Ca) was reduced by 90% in the presence of omega-conotoxin GVIA but was unaffected in the presence of nimodipine, indicating that NO-induced inhibition of I(Ca) is mainly confined to N-type Ca(2+) channels. Exposure of the neurons for 30 min to 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 10 microM), an inhibitor of NO-stimulated guanylyl cyclase, prevented the SNAP-induced reduction in I(Ca). Extracellular application of 8-bromo-cGMP (1 mM) mimicked the effects of NO donors by reducing the peak amplitude of I(Ca) (28.6% of reduction). Action potential configuration and firing frequency during depolarizing current pulses were not altered by the application of SNAP (500 microM) in bladder afferent neurons with TTX-resistant and -sensitive APs. These results indicate that NO acting via a cGMP signaling pathway can modulate N-type Ca(2+) channels in DRG neurons innervating the urinary bladder.

8-Bromo Cyclic Adenosine Monophosphate↗

PubMed2001

The role of bladder afferent pathways in bladder hyperactivity induced by the intravesical administration of nerve growth factor.

PURPOSE: Interstitial cystitis, a chronic disease of the bladder, is characterized by urinary frequency, urgency and suprapubic pain. Nerve growth factor is a substance that may sensitize afferent nerves and induce bladder hyperactivity. It is often increased in the urine of patients with interstitial cystitis. We evaluated the role of Adelta and C fiber afferents in the type of bladder hyperactivity induced by the intravesical administration of nerve growth factor. MATERIALS AND METHODS: A total of 22 Wistar and 8 Sprague-Dawley adult female rats were anesthetized with 1.2 gm/kg urethane given subcutaneously. A transurethral catheter was inserted into the bladder. Some animals were pretreated with 125 mg/kg capsaicin injected subcutaneously 4 days before nerve growth factor administration. Cystometry was performed by slowly filling the bladder at a rate of 0.04 ml per minute for 15 minutes with a volume of up to 0.6 ml. Parameters measured included volume threshold and pressure threshold for inducing the micturition reflex, compliance, bladder contraction amplitude, number of contractions and the inter-contraction interval. Nerve growth factor (0.5 ml of 20 microg/ml in 10% dimethyl sulfoxide) or a vehicle solution (0.5 ml of 10% dimethyl sulfoxide) was infused into the bladder through a transurethral catheter and retained for 1 hour. RESULTS: In Wistar rats nerve growth factor increased the mean number of contractions by 111% versus controls (5.7 versus 2.7, p <0.05), and decreased the mean volume threshold by 41% (0.244 versus 0.412 ml, p <0.05). This effect of nerve growth factor was not detected in Sprague-Dawley rats. Capsaicin pretreatment increased the volume threshold by 59% but did not change nerve growth factor induced bladder hyperactivity. CONCLUSIONS: The intravesical application of nerve growth factor acutely induced bladder hyperactivity in Wistar but not in Sprague-Dawley rats. Because the C fiber afferent neurotoxin capsaicin did not change the effect of nerve growth factor, we believe that Adelta afferent neurons have a major role in nerve growth factor induced bladder hyperactivity.

Administration, Intravesical↗

PubMed2001

Botulinum toxin urethral sphincter injection to restore bladder emptying in men and women with voiding dysfunction.

PURPOSE: Botulinum toxin injection into the external urinary sphincter in spinal cord injured men with detrusor-sphincter dyssynergia has been reported. We expand the clinical use of botulinum toxin for a variety of bladder outlet obstructions and to decrease outlet resistance in patients with acontractile detrusor but who wish to void by the Valsalva maneuver. MATERIALS AND METHODS: Prospective treatment was performed for voiding dysfunction in 8 men and 13 women 34 to 74 years old. The reasons for voiding dysfunction included neurogenic detrusor-sphincter dyssynergia in 12 cases, pelvic floor spasticity in 8 and acontractile detrusor in 1 patient with multiple sclerosis who wished to void by the Valsalva maneuver. Using a rigid cystoscope and a collagen injection needle, a total of 80 to 100 units of botulinum A toxin (Botox) were injected into the external sphincter at the 3, 6, 9 and 12 o'clock positions. RESULTS: Preoperatively 19 of 21 patients were on indwelling or intermittent catheterization. After botulinum A injection all but 1 patient were able to void without catheterization. No acute complications, such as general paralysis or respiratory depression, occurred and none of the patients had dribbling or stress urinary incontinence. Postoperative post-void residual decreased by 71% and voiding pressures decreased on average 38%. Of the 21 patients 14 (67%) reported significant subjective improvement in voiding. Followup ranges from 3 to 16 months, with a maximum of 3 botulinum A injections in some patients. CONCLUSIONS: Urethral sphincter botulinum injection should be considered for complex voiding dysfunction. Encouraging improvement without complications were seen in most of our patients. We have expanded the use of botulinum toxin to treat pelvic floor spasticity and also women.

Adult↗

PubMed2001

Herpes simplex virus mediated nerve growth factor expression in bladder and afferent neurons: potential treatment for diabetic bladder dysfunction.

PURPOSE: Diabetic cystopathy resulting from sensory neuropathy may potentially be treated by direct gene therapy. It has been suggested that nerve growth factor (NGF) has an ameliorative effect in preventing the death in diabetes of afferent dorsal root ganglion neurons, which control bladder function. We investigated NGF gene transfer to the bladder and bladder afferent pathways for treating diabetic cystopathy. We used replication competent and replication defective herpes simplex virus type 1 (HSV-1) vectors that express a functionally active form of the beta-subunit of mouse NGF (beta-NGF) to examine the level and duration of therapeutic gene expression after administration of the vectors. MATERIALS AND METHODS: NGF expression during acute (3 days) and latent (21 days) infections was assessed by enzyme-linked immunosorbent assay (ELISA) and immunohistochemical testing after the injection of 1 x 106 to 1 x 108 pfu HSV-NGF expression vectors into the bladder wall of adult rats. RESULTS: HSV vectors with the strong human cytomegalovirus immediate early promoter used to drive beta-NGF gene expression exhibited increased NGF 3 days after infection in the bladder and L6 to S1 dorsal root ganglia, where bladder afferent neurons are located. ELISA analysis revealed that NGF in the bladder tissue and dorsal root ganglia was increased 7 to 9 and 2 to 4-fold, respectively, over the control vector. Increased NGF expression in L6 to S1 dorsal root ganglia neurons was also detected by immunohistochemical staining with antiNGF antibodies. Extended NGF expression was detected by ELISA 21 days after injection. Replication defective vectors containing HSV-1 latency promoter (LAP-2) driving NGF expressed NGF in the bladder and dorsal root ganglia 21 days after bladder injection. ELISA analysis confirmed an approximate 2 to 3-fold increase of NGF expression in the bladder and L6 to S1 dorsal root ganglia. CONCLUSIONS: The NGF gene may be transferred and expressed in the bladder and bladder afferent pathways using HSV vectors. To our knowledge our study represents the first demonstration of the effectiveness of gene therapy for altering neurotrophic expression in visceral sensory neurons. This technique of gene transfer may be useful for treating certain types of neurogenic bladder dysfunction, such as diabetic cystopathy, in which decreased NGF transport may be a causative factor.

Animals↗

PubMed2001

[Comparison between the anterior chamber configuration in the supine position and that in the prone position in patients with narrow angle].

PURPOSE: To determine whether the anterior chamber configuration of patients with narrow angle is changed in the prone position. PATIENTS AND METHODS: The study included 16 eyes of 16 patients whose anterior chamber angle was classified as Shaffer 2 or narrower. The prone position test(PPT) and ultrasound biomicroscopy (UBM) were performed on every subject. In the UBM examination, the following parameters were measured both in the supine position and in the prone position: the angle-opening distance at 250 microns from scleral spur(AOD 250), the angle-opening distance at 500 microns from scleral spur(AOD 500), the trabecular-iris angle(TIA), and the anterior chamber depth at the center of the cornea(anterior chamber depth, ACD). RESULTS: While the intraocular pressure was higher after PPT than before the test, every subject was evaluated as negative for PPT. Mean value of every parameter examined was lower in the prone position than in the supine position(AOD 250: 114 microns, vs. 128 microns, AOD 500: 121 microns vs. 144 microns, TIA: 12.1 degrees vs. 15.5 degrees, ACD: 1966 microns vs. 2002 microns), and the change in ACD was statistically significant (p = 0.013). CONCLUSIONS: The anterior chamber configuration of patients with narrow angle is changed in prone position. Such a change can occur in patients classified as negative for PPT.

Aged↗

PubMed2001

[Reconstruction of the pulmonary outflow tract without external conduit].

Between October 1987 and December 2000, 50 patients underwent reconstruction of the pulmonary outflow tract without external conduit. The primary malformation was tetralogy of Fallot with pulmonary atresia in 37, double outlet of right ventricle in 4, corrected transposition of the great arteries in 4, transposition of the great arteries with ventricular septal defect and pulmonary stenosis in 4, and double outlet of left ventricle in 2. Mean age at operation was 7.2 years, and mean body weight was 18.3 kg. To reconstruct posterior wall of the pulmonary outflow tract, interposition of autologous pericardium was performed in 24, direct anastomosis between pulmonary trunk and ventriculotomy in 13, longitudinal incision from ventriculotomy through pulmonary trunk in 12, and interposition of left atrial appendage in 1. Anterior wall was reconstructed with monocusp valved outflow patch (MVOP). There was one hospital death and no late death. At 10 years, the freedom from reoperation for pulmonary outflow tract obstruction was 100%, and freedom from reoperation for any cause was 86.6%. Transcatheter stenting for peripheral pulmonary stenosis was performed in 6 patients 2 to 10 months after operation.

Adolescent↗

PubMed2001

[Relationship between skipping breakfast and cardiovascular disease risk factors in the national nutrition survey data].

PURPOSE: To investigate the relationship between skipping breakfast and cardiovascular disease risk factors such as blood pressure, serum lipids, smoking, and lock of exercise. MATERIALS AND METHODS: Data from the National Nutrition survey conducted by the Ministry of Health and Welfare, from 1995 through 1997 were employed for the analysis. Data were used only if subjects were between 20 and 59 years old and had participated in the nutrition survey, and values for height and weight, blood pressure, serum lipids, blood sugar, number of steps per day, and smoking, drinking, and exercise habits were available. The number of subjects with data available for all of the above was 11,778 (4,438 men and 7,340 women). Analyses were performed separately by sex. The relationship between skipping breakfast and continuous variables such as nutrient intake ratio (nutrient intake divided by recommended dietary allowances), body mass index, blood pressure, serum lipids, blood sugar, and the number of steps per day was examined controlling for age using analysis of covariance (ANCOVA). The relationship between skipping breakfast and categorical variables such as smoking, drinking, and exercise habits was assessed controlling for age using Cochran-Mantel-Haenszel statistics. RESULTS: The younger the generation, the higher the rate of skipping breakfast. The rate of skipping breakfast in men was twice as high as in women. The breakfast skippers tended to intake less energy and calcium, both in men and women, that non-skippers. Female skippers tended to intake less iron and vitamin D. The number of steps per day was smaller in breakfast skippers than that in non-skippers both in men and women. Male skippers tended to have higher blood pressure than non-skippers, and female skippers tended to have a higher serum total cholesterol level than non-skippers. The breakfast skippers tended to smoke more than non-skippers, both in men and women, and female skippers tended to drink more alcohol and take less exercise. CONCLUSIONS: Skipping breakfast is related to cardiovascular risk factors such as lack of exercise, smoking, high blood pressure, and high serum total cholesterol.

Adult↗

PubMed2001

[Evaluation of the new pump for home parenteral nutrition Terumo Cafty].

This study was undertaken to evaluate the usefulness of 'Cafty' which is a new infusion pump system for administering home parenteral nutrition (HPN), recently launched by Terumo Corporation. We used 'Cafty' in two patients and found it has more advantages than the existing pump with regard to the following points: 1. Cafty is provided with a display and alarms that indicate pump troubles such as emptiness, occlusion or mis-operation. 2. It is easier to carry because of its smaller size (width 80 mm x length 132 mm x thickness 33 mm) and its lighter weight (320 g). 3. While Cafty operation using a cassette-type tubing and plain control panel to simpler the flow rate accuracy is not reduced. In conclusion, Cafty is better than the existing HPN pump from the viewpoint of safety, portability and easiness.

Adolescent↗

PubMed2001

[Retinal neuronal cell death: molecular mechanism and neuroprotection].

In retinitis pigmentosa, retinal detachment, age-related macular degeneration, and glaucoma, retinal neuronal cells are damaged by a common mechanism, apoptosis. Because apoptosis is an active process that requires de novo expression of a "death message", this process can be controlled by inhibiting the expression of the "death message". We first studied whether a retinal ischemia-reperfusion model can be used as a model for retinal neuronal apoptosis. In the retinal ischemia-reperfusion injuries, typical features of apoptosis, including TUNEL-positive cells, DNA ladder formation, and ultrastructural features of apoptosis were found. Using the model, systematic research to identify the "death message" was done by DNA microarray analysis. About 200 messages were found to be up- or down-regulated during the process of retinal ischemia-reperfusion. These genes were divided into four groups: (1) transcription factor genes, (2) cell cycle-related genes, (3) reactive oxygen scavenger genes and (4) molecular chaperon genes. The possible roles of such genes in neuronal apoptosis following retinal ischemia-reperfusion injury were studied. In the model, reactive oxygen species produced by reperfusion was found to generate lipid peroxides and induced up-regulation of a transcription factor, c-Jun, that further induced aberrant expression of cell cycle-related genes such as cyclin D1 in amacrine cells. However, because no controlled expression of cell cycle-related genes takes place in retinal neurons, amacrine cells died by a G1 arrest mechanism. On the other hand, horizontal cells never expressed cyclin D1 and the cells were found to die by necrosis. The study revealed a possible mechanism of retinal neuronal apoptosis and it also became apparent that different types of neurons use different "death messages". Furthermore, the possibility that inhibition of a "death message" sometimes induces necrosis rather than apoptosis was shown. This means that we need to try inhibition of the death mechanism upstream rather than downstream. Administration of thioredoxin, an endogenous reactive oxygen species that blocks generation of lipid peroxides and thus inhibits the death process upstream, was found to be neuroprotective against retinal ischemia-reperfusion injury. Aberrant expression of c-Jun and cyclin D1 was down-regulated by the treatment. Possible roles of caspases were also studied by using the ischemia-reperfusion injury, RCS rat, and excessive light exposure damage in wild type and caspase-1 deficient mice. Also, application of adeno-associated virus that carries Bcl-xL was tested to find possible neuroprotective effects on RCS rats. Our studies showed that caspase-1 played a more important role in the retinal photoreceptors and caspase-3 was important in neurons in the inner nuclear layer. Caspase-2 was found to be a major caspase in the retinal ganglion cell layer. In agreement with the findings, caspase-1 deficient mice showed less prominent light damage than wild type mice. Gene therapy by Bcl-xL was effective to protect retinal photoreceptor damage in RCS rats.

Animals↗

PubMed2000

Anti-AB titer changes in patients with ABO incompatibility after living related kidney transplantations: survey of 101 cases to determine whether splenectomies are necessary for successful transplantation.

BACKGROUND: A shortage of organ donors for transplantation has become a serious problem throughout the world. To overcome this problem, transplantations across ABO blood barriers have been performed with some success. In general, however, the graft survival rate for transplantation with ABO incompatibility is lower than that of transplantation with ABO compatibility. Unfortunately, the mechanism by which isohemagglutinins might injure an ABO-incompatible graft remains uncertain. Here, the pre- and posttransplantation anti-AB titers in patients who received transplants from ABO-incompatible living donors are reviewed and the pathological findings are compared. METHODS: One hundred and one patients underwent ABO-incompatible living related kidney transplantation (i-LKT) between January 1989 and October 1999 at our hospital. Plasmapheresis and immunoadsorption were performed in all of the i-LKT patients before the transplantation to remove anti-AB antibodies. A splenectomy was also performed during the operation, followed by the local irradiation of the graft with a dose of 150 rad. The anti-AB titers and pathological findings for 93 i-LKT patients, excluding 8 patients who died, were then examined. RESULTS: Immediately after the i-LKT, the anti-AB titer dropped rapidly to below 1:4 in all 93 cases. Seventy of patients (70/93, 75%) showed no elevation in their anti-AB titer during their follow-up. However, the remaining 23 patients (23/93, 25%) showed a significant elevation of their anti-AB titer to over 1:16. Sixteen of these patients (16/93, 17%) exhibited an anti-AB titer of over 1:32. Out of these 16 patients, 11 patients (11/16, 69%) lost their grafts. The anti-AB titer in the remaining five patients (5/16, 31%) spontaneously decreased without any special treatment. Seven patients (7/93, 8%) exhibited an elevated titer of 1:16. Out of these patients, only one patient (1/7, 14%) lost his graft. The elevated titers in the remaining six patients (6/7, 86%) eventually decreased. The graft function improved in patients whose elevated anti-AB titers eventually decreased. Control patients (ABO-compatible kidney transplant patients) showed a normal elevation of their titer values compared with preoperative titers. Pathological findings showed severe humoral rejections in all cases with high anti-AB titers that lost grafts. Humoral rejection was also detected in most of the patients whose anti-AB titer was elevated to over 1:16 after the transplantation, but excellent renal function was resumed once the titers decreased to below 1:4. CONCLUSIONS: In 23 out of 93 i-LKT patients (25%), the anti-AB titers were significantly elevated after the splenectomy. In view of other reports of i-LKT without splenectomy, we feel that a splenectomy in i-LKT patients might be unnecessary. Pathological evidence suggests that the decrease in the anti-AB titer after transplantation might be the net result of plasmapheresis before the operation and the adsorption of antibodies to the endothelium of the transplanted organ after the operation, neither of which is influenced by a splenectomy.

ABO Blood-Group System↗