Biomedical subjects
Publications and source records attributed to T Furuyama.
Immunoelectron microscopy combined with a retrograde tracing technique was carried out to examine the synaptic interaction between neuropeptide Y (NPY)-like immunoreactive (LI) axon terminals and spinal motoneurons innervating bulbocavernosus muscles. Cell bodies and proximal dendrites of these motoneurons were frequently found to receive synaptic inputs from NPY-LI axon terminals.
We studied the localizations of alpha 1 and beta 1 subunits of soluble guanylate cyclase using in situ hybridization. The beta subunit was widely distributed in most neurons throughout the brain, with different levels of expression. The alpha 1 subunit was also distributed throughout the brain; however, it was located in more limited regions. Both subunits were expressed markedly in the glomerular layer of the olfactory bulb, dorsal and ventral striatum, and several regions in the brainstem. Regions with little or no alpha 1 subunit expression, but with marked expression of the beta 1 subunit included the olfactory bulb except for the glomerular layer, pyramidal cell layer in CA1 and granular cell layer in the dentate gyrus of the hippocampus, and many brainstem nuclei. The above regions expressing both subunits are suggested to contain active soluble guanylate cyclase as a target for nitric oxide, and thus may be involved in cellular signal transduction.
We examined the expression of the I, II and III subtypes of voltage-sensitive Na+ channel mRNA in the rat brain using in situ hybridization histochemistry with oligonucleotide probes. The distribution of cells with strongly positive signals was characteristic for each subtype. Synthesis of each subtype of Na+ channel protein may be regulated by differential mRNA expression.
We studied the distribution of type II Ca2+/calmodulin (CaM)-insensitive adenylyl cyclase mRNA in the adult rat brain by in situ hybridization histochemistry. Although type II adenylyl cyclase mRNA was distributed throughout the rostrocaudal extent of the brain, the labeling intensity varied among regions. Strong expression was seen in fairly restricted regions such as CA1 and dentate-gyrus of the hippocampus, some thalamic nuclei, mammillary nucleus, dorsal raphe nucleus, parabrachial nucleus and locus coeruleus. The distribution of this type of mRNA was significantly different from that of type I Ca2+/CaM-sensitive adenylyl cyclase mRNA. The characteristic localization of type II mRNA suggests that this type of adenylyl cyclase may be involved in some neuronal functions different from the type I enzyme.
The present study attempted to explore the gene expression of the subunits (GluR1-4) of the alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA)-type receptor, subunit (GluR5) of kainic acid (KA)-type receptor, NR1 [a subunit of N-methyl-D-aspartate (NMDA) receptors] and the possible glutamate-binding subunit of an NMDA receptor complex in the dorsal horn of the rat spinal cords using in situ hybridization histochemistry. These results were compared with those of the spinal motor neurons. Expression of the subunits of the AMPA-type receptor was also examined at the protein level using immunocytochemistry, with reference to the motor neurons. Although all the four subunits of the AMPA-type receptor were expressed throughout the dorsal horn, the pattern of expression was different according to the dorsal horn region and to the subunits. GluR2 showed the strongest expression in the dorsal horn. Huge numbers of strongly labelled cells formed a dense collection in lamina II and superficial parts of lamina III. Many neurons in lamina II and superficial parts of lamina III expressed GluR1 moderately. Scattered neurons moderately expressing GluR3 were also seen in these regions, while the expression of GluR4 was very low. Labelling of the dorsal horn neurons by the GluR5 probe was low, and NR1 probe and a glutamate-binding subunit of an NMDA receptor complex probe labelled them diffusely with low to moderate intensity. These findings show a close relationship between the glutamergic nociceptive primary afferent system and AMPA-type receptors in which GluR2 is especially highly expressed. The present study further showed that the expression pattern of the glutamate receptors in the spinal sensory neurons differs considerably from that of spinal motor neurons. Motor neurons very strongly express GluR3 and 4, while the expression of GluR2 and GluR1 is moderate and low, respectively. Expression of GluR5 is also low in the motor neurons. However, expression of NR1 and the glutamate-binding subunit of an NMDA receptor complex is very strong. These findings indicate that the subunit composition of the AMPA-type receptors regulating motor neurons is different from that of the AMPA-type receptors in the spinal sensory neurons, and that there are at least two kinds of glutamergic systems which regulate motor neurons: via AMPA-type receptors and via NMDA receptors.
We examined the expression of the beta subunit mRNA of the glycine receptor and the gamma subunit mRNA of the GABAA receptor in the rat dorsal root ganglion (DRG) using in situ hybridization histochemistry with oligonucleotide probes. About 44% and 37% of the all DRG neurons were labeled by the probes for glycine receptor beta subunit and GABAA receptor gamma subunit mRNAs. Labeled neurons were mostly large cells that simultaneously expressed both glycine receptor beta subunit and GABAA receptor gamma subunit mRNA as demonstrated using consecutive sections. Thus, we suggest the possibility that both GABA and glycine presynaptically regulate the activity of neurons involved in low-threshold mechanoreception at axo-axonic synapses in the spinal cord.
A 32-year-old man was diagnosed as having pseudo-Bartter syndrome due to surreptitious habitual vomiting and to maldigestion related to decayed teeth. His chief complaints were muscle pain and weakness. In this case, metabolic alkalosis, hypokalemia, hypochloremia, increased plasma renin activity and aldosterone levels were noticed with marked decreases in urinary chloride excretion. Creatinine clearance (GFR) and renal plasma flow (RPF) were also decreased. Blood pressure was normal, but the pressor response to angiotensin II was attenuated. Before treatment with 0.9% saline infusion, plasma vasopressin (AVP) was not suppressed sufficiently by lowering the plasma osmolality (Posm) with an oral water load (WL), but it normally responded to a rise in Posm due to hypertonic saline infusion. Moreover, plasma AVP was normally suppressed by WL after the replenishment of saline. Plasma atrial natriuretic peptide (ANP) was low before WL, but increased normally in response to WL. However, inconsistent with the normal response in this case, decreases in plasma AVP failed to dilute urinary osmolality and to increase urine flow, irrespective of the levels of plasma ANP. These results indicate that chronic inanition due to surreptitious vomiting causes impaired renal diluting ability through decreases in GFR and RPF, irrespective of the levels of plasma AVP and ANP.
Clinical courses and histopathological changes of four patients with Fabry's disease were discussed in this report. All of them were male and revealed to have angiokeratomas of the skin and markedly decreased activity of alpha-galactosidase--A in leukocytes. They were from different families. No consanguinity was noted. Two of them, around 40 years of age, showed rapid impairment of renal function with simultaneously development of hypertension, progressing to uremia within several months. Their light and electron microscopic findings in renal biopsies were similar: severe degenerative changes in muscle cells of small arteries and arterioles with remarkable swelling of intima, and multiple sclerosing and collaptic lesions in glomeruli. The other 2 patients were about 20 years old and their renal functions were almost normal. No significant changes but fine vacuolization of epithelial cells of glomeruli were observed in renal biopsy specimens. It is concluded that marked degenerative changes in the vessels due to Fabry's disease might be the principal etiology of hypertension and rapid deterioration of renal function.
Renal survival curves for the adult patients at the ages between 15 and 60 with mesangial proliferative glomerulonephritis (MesPGN, N = 366) and membranoproliferative glomerulonephritis (MPGN, N = 76) were calculated using the method designed by Kaplan and Meier. In MesPGN, 80% and 68% of the patients survived 10 and 20 years after biopsy respectively; 88% and 72% survived 10 and 20 years after apparent onset. These results were similar to those analyzed by the research team "progressive renal lesions" in Ministry of Health and Welfare, Japan. When patients were histologically divided into 4 groups according to the index of glomerular lesions, % survival in each group was reduced in relation with the severity of the glomerular lesions, and there was significant difference between renal survival curves of each 2 groups. The influence of urinary protein and hypertension at the time of biopsy on survival curves was also significant. Patients with IgA nephropathy (N = 74) showed the renal survival curve similar to those of MesPGN. The influence of hypertension on % survival was also significant in IgA nephropathy. In MPGN, 53% and 73% of patients survived 10 years after biopsy and apparent onset respectively. Therefore MPGN was poorer in prognosis than MesPGN. These results seem to be important as the controls when we try to study the long-term effects of various therapies against chronic glomerulonephritis.
To study the influence of hypertension on the progression of focal glomerulosclerosis (FGS), we produced an experimental model of FGS in spontaneously hypertensive rats (SHRs) by the combined administration of puromycinaminonucleoside (AMNS) and protamine sulfate (PS). SHRs and normotensive Wistar Kyoto rats as a control strain were given daily injections of subcutaneous AMNS (1 mg/100 gm body weight) and intravenous PS (two separated doses of 2.5 mg/100 mg body weight) for 4 days; they were killed on day 80 after three series of injections at 10-day intervals. The levels of urinary protein, serum creatinine, and urea nitrogen in SHRs given AMNS and PS were elevated throughout the experiment and were significantly higher than these levels in other control groups on day 80. Histology in SHRs given AMNS and PS showed advanced FGS associated with glomerular hypertrophy and widespread interstitial fibrosis. Most small arteries and arterioles showed "onion peel" thickening and fibrinoid necrosis of the intima, which is characteristic of malignant arteriosclerosis. We observed that the gradient of glomerulosclerosis increased from superficial to deep cortical zones; this phenomenon had often been reported in human FGS. However, these distinguished lesions were not found in control groups. Therefore, it is suggested that systemic hypertension is one of the deleterious factors enhancing histologic and functional deterioration in FGS.
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A nine-year-old boy who exhibited mild proteinuria and severe renal dysfunction with short stature, mental retardation, retinitis pigmentosa, deafness, and intracranial calcification was presented. Clinical features of the patient were in the most part consistent with those of Cockayne's syndrome. On the renal biopsy, two-thirds of the glomeruli had fallen into global sclerosis. The remaining one-third showed thickening of the capillary walls and expansion of the mesangial matrix. Immunofluorescence study proved no significant deposition of immunoglobulins or complements. Electron microscopy revealed diffuse homogeneous thickening of the glomerular basement membrane. These histological findings were thought to be characteristic of the Cockayne's syndrome. Although the pathogenesis of Cockayne's syndrome is yet unknown, its renal lesions resembled those of an aged kidney, and a prematurely aged metabolic state was supposed as a principal cause of the disease.
We have developed an enzyme-linked immunosorbent assay (ELISA) for the quantitation of C3 nephritic factor of the alternative pathway of complement (NeFA). Incubation of the NeFA-positive serum (patient KS serum) with normal human serum (NHS) in Mg-EGTA resulted in the formation of C3-B-IgG complex. No complex was formed in EDTA. At first this was detected as three types of complexes: C3-IgG, B-IgG and B-C3, by the combination of antibodies. The reaction mixture in Mg-EGTA was filtered through an ACA 22 column, from which the complexes were eluted in the same part as the first protein peak. When IgG purified from KS serum was incubated with NHS in Mg-EGTA, B-C3 complex increased in proportion to the dose of IgG. These results indicated that only one kind of complex consisting of IgG, C3 and B (IgG-C3-B) was generated by the addition of NeFA to NHS. Serum NeFA could be quantified as the titer of B-C3 complex formed after its incubation with NHS in Mg-EGTA. Using the ELISA method, NeFA was positive in five out of six patients with membranoproliferative glomerulonephritis (MPGN) type II and in only one of 17 with MPGN type I. Titers obtained by the new method were in good accordance with those by C3 conversion and C3bBb stabilization assays for NeFA, and the new method was more exact and simple than the conventional methods.
Renal histopathology in 87 patients, aged over 60, with nephrotic syndrome were studied. In 57 patients diagnosed as primary glomerular disease, membranous glomerulonephritis (MGN) was of the most common histologic type (52.6% of the cases), and mesangial proliferative glomerulonephritis (21.1%), membranoproliferative glomerulonephritis (12.3%) and minimal change (12.3%) were the other types of primary glomerular disease. In the remaining 30 patients, nephrotic syndrome resulted from secondary glomerular diseases including diabetic nephropathy and renal amyloidosis. In comparison with the nephrotic syndrome of younger age group (669 cases, younger than 60 years of age), the incidence of MGN, diabetes and amyloidosis were significantly higher in the elderly. In contrast with unfavorable prognosis of diabetic nephropathy and amyloidosis, most cases of MGN and minimal change recovered from the nephrotic state with steroid treatment even in the elderly. Thus, a statistical finding that the prognosis of senile nephrotic syndrome is unfavorable as a whole, appears to be ascribable to the increased incidence of secondary glomerular diseases rather than to "aging" itself. The present results that the incidence of diabetic nephropathy was high and the outcome of MGN was favorable in the elderly, taken together with the results from other studies in Japan, are fairly different from the results of similar studies in the Western world.
A girl, aged 8, was admitted to a hospital in a state of nephrotic syndrome of one year's duration. The renal biopsy showed mesangial and endocapillary proliferations with lobulation. Dense deposit was not demonstrated by electron microscopy, but lamellation of the lamina densa was found in most of the capillary loops. Her condition was improved by steroid treatment in a few months, but moderate proteinuria persisted. Five and half years later, follow-up biopsy showed typical pathological features of dense deposit disease. It is suggested that the lamellation of the lamina densa in the first biopsy could be related to the dense alteration of glomerular basement membrane in the second biopsy.
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