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PubMed1985

Myofibrillar degeneration--a common type of myocardial lesion and its selective identification by a modified luxol fast blue stain.

Myofibrillar degeneration is a very common form of myocardial damage. It occurs as a disseminated lesion after various forms of injury (e.g. association with cardiovascular surgery, raised intracranial pressure). As a localized alteration it surrounds the coagulation necrosis of infarcts. The present study introduces a modification of the Luxol Fast Blue (LFB) stain as a specific marker of myofibrillar degeneration. In formalin-fixed and paraffin-embedded myocardium of human autopsies and biopsies two LFB-reaction types are demonstrable: A) irregular blue transverse bands and B) a diffuse blue staining of the entire myocyte. The first type corresponds to the cross band lesion typical of myofibrillar degeneration. By electron microscopy it consists of dense aggregations of disorganized myofilaments. The second form exhibits diffusely LFB-coloured cells and ultrastructurally an irregular felt-like splitting of myofibrils. The latter represents another, until now unrecognized type of myofibrillar degeneration which is not clearly detectable when using other staining methods. Since a coagulation necrosis is only faintly LFB-positive, this method is not suitable for the detection of early stages of infarcts. The obvious advantages of the LFB-method are: detection of type, amount and distribution pattern of myofibrillar degeneration in low-power-views, even if myocytes are cut transversely, high sensitivity, easy handling and reliability. The affinity of damaged cells for the LFB-stain seems to be related to the pathogenesis of myofibrillar degeneration, in which abundant Ca++-influx plays a primary role.

Autopsy↗

PubMed2000

Natural and radiation-induced degeneration of primordial and primary follicles in mouse ovary.

The present study deals with the morphological changes of the degenerating primordial and primary follicles induced by gamma-radiation. Prepubertal female mice of 3 weeks old ICR strain were gamma-irradiated with the dose of LD(80(30)) (8.3 Gy). The ovaries were collected at 3, 6 and 12 h after irradiation. The largest cross-sections were prepared by histological semithin sections for microscopical observations. The ratio (%) of normal to atretic follicles decreased with time after the irradiation in primordial follicles and in primary follicles as well. At 6 h after irradiation, the number of degenerated primordial follicles increased. Germinal vesicles disappeared and lipid droplets increased in number. Granulosa cells became round in shape and apoptotic cells started to appear. The ooplasmic membrane was not recognizable. The ratio of normal to atretic primordial follicles in the control group was 62.5. Then it became lower with time after the irradiation. It went down to 51.6, 49.0, 11.1 and 7.1 at 0, 3, 6 and 12 h, respectively. The ratio of normal to atretic primary follicles in the control mouse ovary was 81.3. It was 80.0, 75.0, 45.5 and 33. 3 at 0, 3, 6 and 12 h after irradiation, respectively. It is concluded that the ionizing radiation acutely induces the degeneration of primordial and primary follicles. The pattern of degeneration is one of the following: (1) apoptosis of one or more granulosa cells with a relatively intact oocyte, (2) apoptosis of an oocyte with intact follicle cells, or (3) apoptotic degenerations of both kinds of cells. These results can provide morphological clues for the identification of the degenerating primordial and primary follicles in normal and irradiated mouse ovaries.

Animals↗

PubMed2003

Effect of percutaneous coronary interventions for in-stent restenosis in degenerated saphenous vein grafts without distal embolic protection.

OBJECTIVES: This study was designed to investigate the impact of percutaneous coronary interventions (PCIs) in degenerated saphenous vein grafts (SVGs) without distal embolic protection. BACKGROUND: Distal embolic protection devices have been shown to reduce the incidence of no reflow/slow flow during PCI of de novo lesions in degenerated SVGs. It is unclear whether PCI of in-stent restenosis (ISR) lesions in degenerated SVGs is associated with no reflow/slow flow and whether distal embolic protection is beneficial in these cases as well. METHODS: We studied 54 consecutive patients with treated ISR lesions in degenerated SVGs who underwent PCI without distal embolic protection in a single center. Procedural and in-hospital outcomes were examined. The average age was 71 +/- 8 years; 32% of the patients had diabetes. The mean lesion length was 13 +/- 6 mm and the procedural success rate was 98% (53/54). Cutting balloon angioplasty was used in 46% (25/54) of cases, and a new stent was inserted in 46% (25/54) of patients. Gamma brachytherapy was performed in 19% (10/54) of patients. During the procedure there were no episodes of no reflow/slow flow, and there were no patients with in-hospital Q-wave or non-Q-wave myocardial infarction. There was one in-hospital noncardiac death. CONCLUSIONS: In this consecutive series of patients with ISR of degenerated SVGs undergoing PCI without distal protection, there were no episodes of slow flow/no reflow and no procedure-related myocardial infarctions. It appears that distal embolic protection may not be necessary during PCI of ISR lesions in degenerated SVGs.

Aged↗

PubMed2002

The effects of bone density and disc degeneration on the structural property distributions in the lower lumbar vertebral endplates.

In this study, we hypothesized that vertebral bone density and disc degeneration would affect the structural property distributions of the lower lumbar vertebral endplates (L3-L5). The results may have implications for improving interbody implant designs to better resist subsidence. A 3 mm diameter hemispherical indenter was used to perform indentation tests at 0.2 mm/s to a depth of 3 mm at 27 standardized locations in 55 bony endplates of intact human lumbar vertebrae (L3-L5). The resulting load-displacement curves were used to extract the failure load and stiffness of each test site. Bone density was measured using lateral DEXA scans. Disc condition was determined using a four-point grading scale. Three-way analyses of variance were used to analyze the relationships between the data. The overall failure load decreased with bone mineral density (BMD) in the superior (p < 0.0001) and inferior (p = 0.011) lumbar endplates. In both endplates, the posterolateral regions were significantly stronger than more central regions. With increasing BMD, this difference became more pronounced in the superior endplates only (p = 0.005). Increased disc degeneration was associated with an overall failure load decrease in the inferior lumbar endplates (p = 0.002). The strength in the central regions of the superior endplates was reduced with increasing degeneration, but this was not observed peripherally (p = 0.001). Stiffness magnitude or distribution was not significantly affected by BMD or disc degeneration. The locations of the strongest regions of the endplate did not change with either bone density or disc degeneration. This implies that implant shapes designed using the basic structural property maps for the L3-L5 endplates are appropriate for use in patients with a wide range of pathologies, even though overall failure loads are generally lower in patients with reduced bone density and greater degrees of disc degeneration.

Absorptiometry, Photon↗

PubMedDate not supplied

Influence of cuff muscle fatty degeneration on anatomic and functional outcomes after simple suture of full-thickness tears.

Two hundred twenty shoulders with a rotator cuff tear repaired by simple tendon-to-bone suture were analyzed to determine whether the severity of presurgical fatty degeneration had an influence on their anatomic and functional outcome. Fatty degeneration was evaluated for each muscle with the 5-stage grading system developed by Goutallier et al. A global fatty degeneration index (GFDI), the mean value of the 3 muscles, was calculated for each shoulder. Cuff integrity was evaluated by magnetic resonance imaging (116 cases) or computed arthrotomography scan (104 cases) at a mean 37 months' follow-up, and functional outcomes were evaluated with the Constant score. A recurrent tear was found in 79 cases (36%) and was more frequently encountered in posterosuperior tears. The likelihood of a recurrent tear was greater for tendons whose muscle showed fatty degeneration greater than grade 1. Fatty degeneration of the infraspinatus or subscapularis muscles had an influence on supraspinatus tendon outcome. A GFDI lower than 0.5 was necessary to yield less than 25% retears. The mean global Constant score was 75 at revision, significantly lower when a retear was present (70.5 versus 77.5). In the subgroup of watertight cuffs, it was lower when GFDI was higher. Fatty degeneration is an important prognostic factor in rotator cuff surgery.

Adipose Tissue↗

PubMed1996

Effect of high molecular weight hyaluronan on cartilage degeneration in a rabbit model of osteoarthritis.

The effects of high molecular weight hyaluronan (HA) on cartilage degeneration were investigated in a partial menisectomy model of osteoarthritis (OA) in the rabbit knee. This study compared HA80 (0.8 x 10(6) Da, 1%), HA190 (1.9 x 10(6) Da, 0.01-1%) and saline. HA (0.1 ml/kg) or saline were injected intra-articularly twice a week immediately after surgery. Degenerative changes in femoral and tibial cartilages were graded histopathologically 2 and 4 weeks after surgery. Two weeks after surgery, HA190, only when used at a 1% concentration, resulted in a dramatic inhibition of cartilage degeneration in both the femoral condyle and the tibial plateau (P < 0.01). Two weeks after surgery, the protection against cartilage degeneration was significantly (P < 0.05) greater with HA190 than with HA80. Four weeks after surgery, only the femoral cartilage degeneration was significantly and similarly inhibited with HA190 (P < 0.01) and HA80 (P < 0.05). Scanning electron micrographs of femoral cartilage showed that cartilage degeneration was less severe with HA190 than with saline. These results might suggest that, in the rabbit model, intra-articular administration of higher molecular weight HA is more effective than lower molecular weight HA in inhibiting cartilage degeneration in early OA.

Animals↗

PubMed2003

Lack of association between lumbar disc degeneration and osteophyte formation in elderly japanese women with back pain.

Our study was designed to assess the contributions of the physical and constitutional factors to osteophyte formation, disc degeneration, and bone mineral density (BMD) in lumbar vertebrae of elderly postmenopausal women. A total of 126 Japanese women with back pain, aged over 60 years, were invited to participate in the study. Then 80 subjects with a full set of data for physical examinations, radiographs, MRI, and DXA were examined. TaqI polymorphism of vitamin D receptor (VDR) gene was examined in 60 subjects. Prevalence rates of osteophytes (on radiographs) and disc degeneration (on MRI) were 61 and 68%, respectively. Body weight and BMI correlated significantly with anteroposterior (AP) and lateral (LAT) BMD (r = 0.354 for weight, r = 0.347 for BMI) and mean osteophyte area (r = 0.557 for weight, r = 0.486 for BMI), and body weight also correlated with number of discs with osteophytes. However, these did not correlate with the disc area or the number of degenerated discs. Stepwise regression analysis revealed that body weight and LAT-BMD values independently related to the osteophyte area. Disc area (r = 0.386 for AP view) and osteophyte area (r = 0.384 for AP view) significantly correlated with BMD. However, disc area and osteophyte area did not correlate with each other (r = 0.056). The proportion of degenerated discs was higher in the lower lumbar discs, but not the proportion of discs with osteophytes. Frequencies of T and t alleles of VDR did not correlate with disc degeneration, osteophyte formation, or osteoporosis. Our data showed that increases in osteophyte formation and BMD in the lumbar vertebrae are influenced by body weight and BMI, but did not correlate with disc area, which correlated inversely with BMD. Disc degeneration and osteophyte formation seem to represent two different factors that affect lumbar spine in elderly women.

Aged↗

PubMedDate not supplied

[Comparative analysis of lumbar spine degeneration documented by x-rays versus large specimen cryomicrotome sections].

AIM OF THE STUDY: The extent of degenerative changes in the lumbar spine as seen on conventional radiographs is interpreted on the basis of visualized osseus structures and indirect signs such as diminution of disc height. In order to analyze the accuracy of these interpretations we compared and correlated different stages of degeneration in conventional radiographs with cuts of large-specimen cryomicrotome sections (LSCS), offering a direct macroscopic vision of the degenerative anatomic features. METHOD: A total of 50 human cadaver lumbar spines with 251 spine segments (Th 12 - S1) was investigated by plain radiograms and LSCS. The degenerative changes were differentiated into 5 stages for both diagnostic measures. Criteria for radiological degeneration were: diminution of disc space, presence of osteophytes and sclerosis of the endplates. Degenerative changes as seen by LSCS were evaluated by the following features: cracks in the endplate, bleeding into the intervertebral disc, alignment of the annulus fibrosus fibres and osseous alterations in the spine segment. RESULTS: Complete matches of the evaluated radiological and macroscopic stages of degeneration were observed in 206 cases. A difference of 1 degree on the degeneration scale was registered in 42 segments, whereas a difference of 2 degrees was seen in 3 cases. The correlation coefficient between the degeneration stages of the two diagnostic measures scored rho = 0.883. CONCLUSION: The comparison of the different degrees of degeneration in the lumbar spine as evaluated by both plain radiographs and LSCS revealed a good correlation.

Adolescent↗

PubMedDate not supplied

[Application of a dynamic pedicle screw system (DYNESYS) for lumbar segmental degenerations - comparison of clinical and radiological results for different indications].

AIM: Evaluation of the efficacy of a dynamic stabilizing system for different indications using medium-term clinical and radiological parameters. METHODS: Out of a total of 70 evaluated patients, 35 showed initial disc degeneration and disc herniation (group 1). In this group, additional nucleotomy was performed. Group 2 included 22 patients with initial osteochondrosis and facet joint osteoarthritis. 13 patients suffered from progressive segment degeneration or degenerative spondylolisthesis (group 3). Clinical evaluation was performed preoperatively, three months postoperatively and at follow-up (33 months). Examinations included subjective and objective measures using the Oswestry Index and VAS as well as radiographs and MRI. RESULTS: Oswestry Index and VAS improved significantly in groups 1 and 2 and remained improved until follow-up. Group 3 showed no significant changes. The evaluation of radiographs and MRI of groups 1 and 2 revealed no progression of the degeneration either at the operated segments or at the adjacent segments. In group 3, 9 cases of progressive degeneration of the operated segments and 3 cases of adjacent segment degeneration were found. Out of 5 implant-associated complications 4 were observed in group 3. CONCLUSION: Dynesys is able to compensate initial morphological changes and to prevent progression of segment degeneration. The system seems not to be indicated for treating marked deformities or if osseous decompression needs to be performed.

Adult↗

PubMed1986

[Degeneration theory in psychiatry].

Degeneration (called "dégénérescence" in French and "Degenerationslehre" in German terminology) as a theory of human retrogression manifested by degenerative signs in individuals, was a major factor in medicine and especially in psychiatry during the second half to the 19th century and at the beginning of the 20th century. Theories of retrogression seemed to supply conclusive hypothetic explanatory models for a wide variety of deviations from so-called "standard" values of health criteria for neurological diseases, brain disorders and mental diseases. The theory of degeneration, or retrogression, was closely interlinked with the complex ideological pattern that formed the background of philosophy and natural science during the nineteenth century. The theory of degeneration experienced mutual interaction and stimulation by the interplay with various other theories that were "en vogue" at that time, such as the development of positivistic natural science and of the theory of evolution, which in turn gave birth to the theories of social Darwinism, eugenics, genetics and to the development of biological-vitalistic approaches. In contrast with the other fields of medicine, anatomic pathology was unable to uncover any aetiological linkups for the various types of mental diseases. Hence, the theories of degeneration seemed to offer a conclusive concept for the genesis of mental disorders. The concept of degeneration was based on the theory of polymorphism which in turn positioned the wide range of neurological, mental and brain diseases within the descending series of progressing degeneration.

Europe↗

PubMed2003

Actinic degeneration and pigmentary change in association with psoralen and UVA treatment: a 20-year prospective study.

BACKGROUND: Changes in the appearance of the skin including actinic degeneration and pigmentary changes have been noted in patients treated with psoralen and UVA (PUVA). OBJECTIVE: Our purpose was to quantify risk factors for increased extent and progression of actinic degeneration and pigmentary changes in the skin of patients treated with PUVA. METHODS: On the basis of standardized dermatologic examination conducted in 1977 and 1998 of patients enrolled in the PUVA Follow Up Study, we assessed the prevalence of and changes in the extent of actinic degeneration and pigmentary abnormalities on the hands and buttocks. RESULTS: From 1977 to 1998, the prevalence of moderate or severe actinic degeneration increased from 15.6% to 60.5% on the hands and from 2.2% to 21.3% on the buttocks. During this same period, the prevalence of pigmentary changes of this degree increased from 15.6% to 58.6% on the hands and 12.6% to 24.7% on the buttocks. Extent of exposure to PUVA was the strongest predictor of an increased extent of clinical actinic degeneration or pigmentary change. CONCLUSION: Long-term exposure to PUVA is associated with persistent increases in actinic degeneration and pigmentary abnormalities of the skin on both usually sun-exposed and sun-protected sites.

Aged↗

PubMed1997

Magnetization transfer and spin lock MR imaging of patellar cartilage degeneration at 0.1 T.

PURPOSE: To investigate magnetization transfer (MT) parameters and rotating frame relaxation time T1 rho in patellar cartilage at different levels of degeneration. MATERIAL AND METHODS: Thirty cadaveric patellae were examined at 0.1 T using the time-dependent saturation-transfer MT technique and the spin lock (SL) technique. In an SL experiment, nuclear spins are locked with a radiofrequency (RF) field, and the locked nuclear magnetization relaxes along the magnetic component of the locking RF field. The specimens were divided into three groups according to the level of cartilage degeneration. MT parameters and T1 rho were measured. RESULTS: The MT effect was greater in degenerated cartilage than in normal cartilage. T1 rho was longer in advanced cartilage degeneration than in intermediate cartilage degeneration. CONCLUSION: The results suggest that more studies are needed to fully establish the value of SL imaging in cartilage degeneration.

Adolescent↗

PubMed1997

The phosphatidylinositol transfer protein domain of Drosophila retinal degeneration B protein is essential for photoreceptor cell survival and recovery from light stimulation.

The Drosophila retinal degeneration B (rdgB) gene encodes an integral membrane protein involved in phototransduction and prevention of retinal degeneration. RdgB represents a nonclassical phosphatidylinositol transfer protein (PITP) as all other known PITPs are soluble polypeptides. Our data demonstrate roles for RdgB in proper termination of the phototransduction light response and dark recovery of the photoreceptor cells. Expression of RdgB's PITP domain as a soluble protein (RdgB-PITP) in rdgB2 mutant flies is sufficient to completely restore the wild-type electrophysiological light response and prevent the degeneration. However, introduction of the T59E mutation, which does not affect RdgB-PITP's phosphatidylinositol (PI) and phosphatidycholine (PC) transfer in vitro, into the soluble (RdgB-PITP-T59E) or full-length (RdgB-T59E) proteins eliminated rescue of retinal degeneration in rdgB2 flies, while the light response was partially maintained. Substitution of the rat brain PITPalpha, a classical PI transfer protein, for RdgB's PITP domain (PITPalpha or PITPalpha-RdgB chimeric protein) neither restored the light response nor maintained retinal integrity when expressed in rdgB2 flies. Therefore, the complete repertoire of essential RdgB functions resides in RdgB's PITP domain, but other PITPs possessing PI and/or PC transfer activity in vitro cannot supplant RdgB function in vivo. Expression of either RdgB-T59E or PITPalpha-RdgB in rdgB+ flies produced a dominant retinal degeneration phenotype. Whereas RdgB-T59E functioned in a dominant manner to significantly reduce steady-state levels of rhodopsin, PITPalpha-RdgB was defective in the ability to recover from prolonged light stimulation and caused photoreceptor degeneration through an unknown mechanism. This in vivo analysis of PITP function in a metazoan system provides further insights into the links between PITP dysfunction and an inherited disease in a higher eukaryote.

Aging↗

PubMed1977

Hereditary retinal degeneration in Drosophila melanogaster. A mutant defect associated with the phototransduction process.

Two genes in Drosophila, rdgA and rdgB, which when defective cause retinal degeneration, were discovered by Hotta and Benzer (Hotta, Y., and S. Benzer. 1970. Proc. Natl, Acad. Sci. U. S, A. 67:1156-1163). These mutants have photoreceptor cells that are histologically normal upon eclosion but subsequently degenerate. The defects in the rdgA and rdgB mutants were localized by the study of genetic mosaics to the photoreceptor cells. In rdgB mutants retinal degeneration is light induced. It can be prevented by rearing the flies in the dark or by blocking the receptor potential with a no-receptor-potential mutation, norpA. Vitamin A deprivation and genetic elimination of the lysosomal enzyme acid phosphatase alsoprotect the photoreceptors of rdgB flies against light-induced damage. The photopigment kinetics of dark-reared rdgB flies appear normal in vitro by spectrophotometric measurements, and in vivo by measurements of the M potential. In normal Drosophila, a 1-s exposure to intense 470-nm light produces a prolonged depolarizing afterpotential (PDA) which can last for several hours. In dark-reared rdgB mutants the PDA lasts less than 2 min;; it appears to initiate the degeneration process, since the photoreceptors become permanently unresponsive after a single such exposure. Another mutant was isolated which prevents degeneration in rdgB flies but which has a normal receptor potential. This suppressor of degeneration is an allele of norpA. It is proposed that the normal norpA gene codes for a product which, when activated, leads to the receptor potential, and which is inactivated by the product of the normal rdgB gene.

Acid Phosphatase↗

PubMed1990

Increased germ cell degeneration during postprophase of meiosis is related to increased serum follicle-stimulating hormone concentrations and reduced daily sperm production in aged men.

Aged men, known to have high serum gonadotropin levels and reduced spermatogenic potential, were used to study the relationship between serum follicle-stimulating hormone (FSH) and germ cell degeneration. Serum hormones were measured from blood obtained at autopsy. Phase-contrast cytometry was used to enumerate germ cells in homogenates of fixed testes from 13 younger (24-51 yr) and 14 aged (69-90 yr) men. The developmental steps of spermatogenesis during which germ cells degenerate were determined by comparing potential daily sperm production based on primary spermatocytes with daily sperm production based on two different types of spermatids. During spermiogenesis, there was no significant degeneration in the younger or aged men. During postprophase of meiosis, aged men had more (p less than 0.01) germ cell degeneration, significantly lower (p less than 0.05) serum testosterone, and greater (p less than 0.01) serum FSH than did younger men. Germ cell degeneration during postprophase of meiosis was negatively correlated (p less than 0.01) to daily sperm production and significantly (p less than 0.01) related to serum concentrations of FSH. As revealed in these aged men, meiotic germ cell degeneration has a direct effect on daily sperm production and is significantly related to serum FSH concentrations.

Adult↗

PubMed2000

The relationship between disc degeneration, facet joint osteoarthritis, and stability of the degenerative lumbar spine.

Degenerative processes in the disc and facet joints affect the stability of the motion segment. The exact relations among disc degeneration, facet joint osteoarthritis, and the kinematics of the motion segment are not well defined in the literature. Magnetic resonance imaging and functional radiography of the lumbar spine were analyzed to examine the relations among segmental instability, facet joint osteoarthritis, and disc degeneration in patients with degenerative disorders of the lumbar spine. Seventy consecutive patients (mean age, 46 years) had both magnetic resonance imaging and flexion and extension radiographs of the lumbar spine. The lumbar instability was classified into abnormal tilting on flexion, rotatory instability in the sagittal plane, and translatory instability. Translatory instability was subdivided into anterior, posterior, and anteroposterior translatory instability. Disc degeneration as seen on T2-weighted sagittal images was classified into five grades. Facet joint osteoarthritis as seen on axial T1-weighted images was divided into four grades. This study revealed that the kinematics of the lumbar motion segment are affected by disc degeneration and facet joint osteoarthritis. Abnormal tilting movement on flexion and anteroposterior translatory instability both had negative associations with facet joint osteoarthritis. However, anterior translatory instability was positively associated with disc degeneration and facet joint osteoarthritis. Rotatory instability in the sagittal plane and posterior translatory instability were not associated with disc degeneration and facet joint osteoarthritis.

Adolescent↗

PubMed2001

Nucleus pulposus allograft retards intervertebral disc degeneration.

Autogenous implantation of nucleus pulposus or nucleus pulposus cells that were activated by coculture retards intervertebral disc degeneration, but harvesting such grafts causes disc degeneration at the donor site. This study examined whether nucleus pulposus allografts similarly retard disc degeneration and whether such allografting induces immunologic rejection. Japanese White rabbits served as donors and recipients for allografts. Lumbar disc degeneration was induced by aspirating the nucleus pulposus. Two weeks later, intact nucleus pulposus or nucleus pulposus cells were injected and compared with a sham procedure and normal control. The recipients' discs were examined histologically and immunologically at intervals for 16 weeks. Discs receiving an intact nucleus pulposus showed the least degeneration, followed by discs receiving nucleus pulposus cells, both of which were better than no treatment. These findings correlated directly with the intensity of immunochemical staining for Type II collagen. Allogeneic grafts did not induce any appreciable host-versus-graft response. Injection of nucleus pulposus and nucleus pulposus cells retards intervertebral disc degeneration. However, injection of intact nucleus pulposus is more effective than injection of nucleus pulposus cells alone. The intercellular matrix plays an important, but poorly understood, role in preserving intervertebral discs.

Animals↗

PubMed1991

Spatial distribution of fiber degeneration in acute hypoglycemic neuropathy in rat.

Hypoglycemia may cause axonal nerve fiber degeneration, but to do so it must be severe (less than 1.5 mmol/L) and of long duration (greater than or equal to 12 hours). Since in our previous study, systemic PO2, PCO2, pH, blood pressure, temperature, and hematocrit were maintained within physiologic limits, fiber degeneration cannot be attributed to systemic hypoxia. In this study the spatial distribution of axonal degeneration was assessed in transverse epoxy sections and teased fibers from different proximal-to-distal levels of nerves of the lower limb of the rats. Reactions in lumbar spinal motor neurons, spinal ganglia, and fasciculus gracilis were also studied. Axonal degeneration was the characteristic fiber alteration and it predominated in central fascicular distributions of distal sciatic, proximal tibial, and proximal peroneal nerves. This proximal-to-distal and central fascicular spatial distribution is not typical of distal polyneuropathy or of neuronal degeneration, but it is characteristic of a focal or multifocal nerve trunk neuropathy. Although local hypoxic-ischemic injury, possibly mediated by enhanced sympathetic tone, has not been excluded, we postulate a generalized deficiency of energy substrate manifesting itself by fiber degeneration at watershed zones of poorest perfusion.

Animals↗