Current status and future prospects of the Japanese orthopaedic association national registry (JOANR), Japan's first national registry of orthopaedic surgery

The Japanese Orthopaedic Association National Registry (JOANR) is Japan's first national registry of orthopaedic surgery, which has been developed after having been selected for the Project for Developing a Database of Clinical Outcome approved by the Health Policy Bureau of the Ministry of Health, Labour and Welfare. Its architecture has two levels of registration, one being the basic items of surgical procedure, disease, information on surgeons, surgery-related information, and outcome, and the other being detailed items in the affiliated registries of partner medical associations. It has a number of features, including the facts that, because it handles medical data, which constitute special care-required personal information, data processing is conducted entirely in a cloud environment with the imposition of high-level data security measures; registration of the implant data required to assess implant performance has been automated via a bar code reader app; and the system structure enables flexible collaboration with the registries of partner associations. JOANR registration is a requirement for accreditation as a core institution or partner institution under the board certification system, and the total number of cases registered during the first year of operation (2020) was 899,421 registered by 2,247 institutions, providing real-world evidence concerning orthopaedic surgery.

The enhancement of CCL2 and CCL5 by human bone marrow-derived mesenchymal stem/stromal cells might contribute to inflammatory suppression and axonal extension after spinal cord injury

Human bone marrow-derived mesenchymal stem/stromal cells (hMSCs) have shown potential in facilitating recovery from spinal cord injury (SCI) through communicating with microglia/macrophages (MG/MΦ). We here focused on chemokines as a candidate for the communication. Selected MG/MΦ-related chemokines were determined gene expression after SCI and further focused CCL2/CCR2 and CCL5/CCR5 to estimate role of the chemokines by hMSCs. Male C57/BL6 mice were subjected to spinal cord transection. Gene expression was assayed in the spinal cords following SCI for selected MG/MΦ-related chemokines and their receptors. hMSCs (5×10⁵ cells) were then transplanted into parenchyma of the spinal cord, and the expressions of the Ccl2/Ccr2 and Ccl5/Ccr5 axes, inflammation, MG/MΦ-polarization, and axonal regeneration were evaluated to measure the influence of the hMSCs. Finally, mouse CCL5 was injected into the spinal cords. Acute increases in gene expression after SCI were observed for most chemokines, including Ccl2; chronic increases were observed for Ccl5. CCL2⁺-cells merged with NeuN⁺-neurons. CCR2⁺ immunoreactivity was principally observed in Ly-6G⁺/iNOS⁺-granulocytes on postoperative day (pod) 1, and CCL5⁺ and CCR5⁺ immunoreactivity overlapped with NeuN⁺-neurons and F4/80⁺-MG/MΦ on pod 14. The hMSC transplantation enhanced Ccl2 and Ccl5 and improved locomotor activity. The hMSC implantation did not alter the number of Ly-6G⁺/CCR2⁺ but decreased Il1, Elane, and Mpo on pod 3. Conversely, hMSC transplantation increased expression of Zc3h12a (encodes MCP-1-induced protein) on pod 14. Moreover, hMSC increased the Aif1, and two alternatively activated macrophage (AAM)-related genes, Arg1 and Chil3 (Ym1), as well as axonal regenerative markers, Dpysl2 and Gap43. Gene expression indicative of AAM polarization and axonal regeneration were partially recovered by CCL5 injection. These results suggest that hMSC implantation increases Ccl2 and Ccl5, improves locomotor activity, enhances MG/MΦ polarization to AAM, and increases the gene expression of axonal regenerative markers. These functions of hMSCs might be partially mediated by the CCL2/CCR2 and CCL5/CCR5 axes.

Pituitary adenylate cyclase-activating polypeptide (PACAP) contributes to the proliferation of hematopoietic progenitor cells in murine bone marrow via PACAP-specific receptor

Pituitary adenylate cyclase-activating polypeptide (PACAP, encoded by adcyap1) plays an important role in ectodermal development. However, the involvement of PACAP in the development of other germ layers is still unclear. This study assessed the expression of a PACAP-specific receptor (PAC1) gene and protein in mouse bone marrow (BM). Cells strongly expressing PAC1⁺ were large in size, had oval nuclei, and merged with CD34⁺ cells, suggesting that the former were hematopoietic progenitor cells (HPCs). Compared with wild-type mice, adcyap1^−/− mice exhibited lower multiple potential progenitor cell populations and cell frequency in the S-phase of the cell cycle. Exogenous PACAP38 significantly increased the numbers of colony forming unit-granulocyte/macrophage progenitor cells (CFU-GM) with two peaks in semi-solid culture. PACAP also increased the expression of cyclinD1 and Ki67 mRNAs. These increases were completely and partially inhibited by the PACAP receptor antagonists, PACAP6-38 and VIP6-28, respectively. Little or no adcyap1 was expressed in BM and the number of CFU-GM colonies was similar in adcyap1^−/− and wild-type mice. However, PACAP mRNA and protein were expressed in paravertebral sympathetic ganglia, which innervate tibial BM, and in the sympathetic fibers of BM cavity. These results suggested that sympathetic nerve innervation may be responsible for PACAP-regulated hematopoiesis in BM, mainly via PAC1.

Human mesenchymal stem/stromal cells suppress spinal inflammation in mice with contribution of pituitary adenylate cyclase-activating polypeptide (PACAP)

Background

Adult human mesenchymal stem/stromal cells (hMSCs) from bone marrow have been reported to exhibit beneficial effects on spinal cord injury (SCI). A neuropeptide, pituitary adenylate cyclase-activating polypeptide (PACAP) is known to decrease neuronal cell death and inflammatory response after ischemia, SCI, and other neuronal disorders. Recently, we found that expression of the gene for mouse PACAP (Adcyap1) was greater in animals receiving hMSCs with neural injury such as ischemia. However, the association of PACAP with hMSCs to protect nerve cells against neural injuries is still unclear.

Methods

Wild-type and PACAP-gene-deficient (Adcyap1^+/−) mice were subjected to spinal cord transection, and hMSCs (5 × 10⁵ cells) were injected into the intervertebral spinal cord on day 1 post-operation (p.o.). Locomotor activity, injury volume, retention of hMSCs, mouse and human cytokine genes (which contribute to macrophage (MΦ) and microglial activation), and Adcyap1 were evaluated.

Results

hMSCs injected into wild-type mice improved locomotor activity and injury volume compared with vehicle-treated mice. In contrast, non-viable hMSCs injected into wild-type mice, and viable hMSCs injected into Adcyap1^+/− mice, did not. Wild-type mice injected with hMSCs exhibited increased Adcyap1 expression, and observed PACAP immunoreaction in neuron-like cells. Gene expression levels for IL-1, tumor necrosis factor α (TNFα), interleukin-10 (IL-10), and transforming growth factor β (TGFβ) decreased, while that for interleukin-4 (IL-4) increased, in hMSC-injected wild-type mice. In contrast, IL-1, TGFβ, and IL-4 gene expression levels were all abolished in hMSC-injected Adcyap1^+/− mice on day 7 post-operation. Moreover, the mice-implanted hMSCs increased an alternative activating macrophage/microglial marker, arginase activity. The human gene profile indicated that hMSCs upregulated the gene of IL-4 and growth factors which were reported to enhance Adcyap1 expression. Finally, we demonstrated that hMSCs express human ADCYAP1 and its receptor gene after the inflammation-related interferon-γ (IFNγ) in vitro.

Conclusions

These results suggest that hMSCs attenuate the deleterious effects of SCI by reducing associated inflammatory responses and enhancing IL-4 production. This effect could be mediated in part by cell-cell cross-talk involving the neuropeptide PACAP.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-015-0252-5) contains supplementary material, which is available to authorized users.

Establishment and characterization of primary adult microglial culture in mice

Microglial cells account for approximately 12-15 % of the cells in the central nervous system (CNS). Microglial cells are polarized by pathological stimuli such as cytokines, chemokines, and growth factors, and play important roles in the deterioration and repair of the CNS. Here, we established cultures of primary microglial cells isolated from the brains of adult C57/BL6 mice using Percoll density gradients. The cells were cultured and stained with antibodies against CD11b, glial fibrillary acidic protein, myelin basic protein and NeuN to determine microglial, astroglial, oligodendroglial, and neuronal cells respectively. Moreover, the cells were exposed to interferon-γ (IFNγ) plus interleukin-1β (IL-1β) or IL-4 for 24 h to demonstrate the activating phenotypes with inducible nitric oxide synthase (iNOS), Ym1, and Iba-1 immunoblotting. At least 95 % of the cultured cells were CD11b-positive and -negative for astroglial, neuronal, and oligodendrocyte markers. IFNγ plus IL-1β treatment resulted in classical activation, which was represented by an increase in iNOS. The cells also displayed alternative activation, which increased Ym1 when treated with IL-4. The present study indicates that the microglial cells isolated as described here are a useful tool for elucidating adult microglial function.

POSTERIOR ENDOSCOPIC DISCECTOMY USING ENDOSCOPIC LUMBAR DISCECTOMY SYSTEM (ELDS)

Characteristics of endoscopic lumbar discectomy system (ELDS) developed in Japan were introduced, and the first 50 cases were clinically evaluated. Patients included: 4 cases of double disc herniationat two levels; 1 cranially and 3 caudally migrated discs; 3 spinal canal stenosis; 1 synovial cyst; and 3 persistent ring apophysis. In 4 central disc herniation cases, 1 case was approached bilaterally and other 3 cases unilaterally. Using a step-dilator system, targeting inter-laminar space was exposed and a tubular retractor either of 16 or 18 mm diameter was inserted through the paravertebral muscle. A 30° endoscope of 3 mm diameter was installed to a tubular retractor. Partial laminectomy and resection of ligamentum flavum were performed using microsurgical instruments, followed by medial retraction of the symptomatic nerve root and incision of the herniated disc. Average surgery time was 119 minutes and estimated blood loss was 49.1 gm. Patients left their bed at 1.9 days post-operative and average hospital-stay was 11.5 days. Recovery ratio of the Japanese Orthopedic Association (JOA) score was 80.7%. Average visual analog pain scale at the first day post-operative was 2.9 cm and CRP at the 7th day was 0.4 mg/dl. Adjacent two-level discectomy was possible with one midline skin incision. Coexistence of severe lumbar spinal canal stenosis was most technically demanding pathology. ELDS provided brightened and magnified surgery field. This can be an effective assistant for minimally invasive lumbar disc surgery.

An Analysis of Male-Recombination Elements in a Natural Population of DROSOPHILA MELANOGASTER in South Texas

Genomes from a group of Drosophila melanogaster collected from a natural population at San Benito, South Texas, in March of 1975 were analyzed for the presence of male-recombination elements. All three autosomes and both sex chromosomes were examined, with emphasis placed on the two major autosomes, the second and third chromosomes. In samples of 16 second and 16 third chromosomes, at least half, but not all, of each were found to carry male-recombination elements. It is suggested, although the data are not conclusive, that some of the fourth, X, and Y chromosomes might also be associated with male-recombination elements.-When a male-recombination element, or elements, was located in the second chromosome, relatively more male recombination was induced in the second than in the third chromosome. This situation was reversed when the element(s) was located in the third chromosome.-Distortion of transmission frequency, one of the characteristics of previously studied second chromosome lines associated with male recombination, was confirmed for these second chromosomes that carried male-recombination elements. Similar, but less pronounced, distortion was observed for the third chromosome lines that carried male-recombination elements.

Spinal cord anterior decompression for delayed spinal cord paralysis after osteoporotic vertebral compression fracture: application of thoracoscopic approach

The purpose of this study was to evaluate the efficacy of thoracoscopic techniques applied for anterior spinal cord decompression and fusion in osteoporotic thoracolumbar vertebral pseudoarthrosis with paralysis that otherwise require open thoracotomy and diaphragm section. Thirteen patients (average age, 65.7 years old) underwent this operation. Unilateral lung ventilation, otherwise bilateral high frequency jet ventilation was applied for general anesthesia. Three ports were routinely prepared through the intercostal spaces. Minimal subperiosteal dissection of the diaphragm was made from its insertion to L1 vertebra by 2 cm. Following corpectomy procedure of collapsed vertebra, spinal cord was decompressed and spinal fusion was performed in either of one or two stages. Spinal cord decompression could be achieved under bright illumination and a magnified view by assistance of endoscope system. Anterior spinal reconstruction could be performed by a titanium mesh cage packed with local bone in 9, or by autogenic iliac strut bone graft in 4 cases. There was no mortality and no major endoscope-related morbidity such as dural tear, spinal cord, lung, or major vascular injury except one case of pulmonary embolism. By avoiding open thoracotomy, thoracoscopic approach resulted in less postoperative wound pain and better respiratory function for such aged high-risk patients.

Increased mitochondrial DNA oxidative damage after transient middle cerebral artery occlusion in mice

Oxidative stress and DNA oxidation play important roles in the induction of ischemic neuronal cell death. However, the subcellular source of oxidized DNA detected by 8-hydroxy-2'-deoxyguanosine (8-OHdG) after ischemia has not been clarified although it is known to increase in the brain after ischemia. One-hour transient ischemia of the middle cerebral artery was induced in mice utilizing an intraluminal filament. The occurrence of superoxide anion as an ethidium (Et) signal, 8-OHdG, cytochrome c release and neuronal cell death were examined using immunohistological and biochemical techniques in sham-operated control (0h) and 1, 3, 6, 24, or 96h after reperfusion. Et signals were prominent in the cortical neurons of ipsilateral hemisphere 3h after reperfusion. Strong 8-OHdG immunoreactivity was observed 3-6h after reperfusion. Immunoassays after cell fractionation revealed a significant increase of 8-OHdG in mitochondria 6h after reperfusion. Immunohistochemistry revealed that the 8-OHdG immunoreactivity colocalized with a neuronal marker, microfilament 200 and a mitochondrial marker, cytochrome oxidase subunit I. Cytochrome c rose in cytoplasm at 6h and TUNEL-positive neurons noted 6-24h after ischemia. The present results suggest the possibility that the mitochondrial damage including mitochondrial DNA oxidation might be responsible for the induction of ischemic neuronal cell death.

Neuronal damage in rat brain and spinal cord after cardiac arrest and massive hemorrhagic shock*

OBJECTIVE

Severe global ischemia often results in severe damage to the central nervous system of survivors. Hind-limb paralysis is a common deficit caused by global ischemia. Until recently, most studies of global ischemia of the central nervous system have examined either the brain or spinal cord, but not both. Spinal cord damage specifically after global ischemia has not been studied in detail. Because the exact nature of the neuronal damage to the spinal cord and the differences in neuronal damage between the brain and spinal cord after global ischemia are poorly understood, we developed a new global ischemia model in the rat and specifically studied spinal cord damage after global ischemia. Further, we compared the different forms of neuronal damage between the brain and spinal cord after global ischemia.

DESIGN

Randomized, controlled study using three different global ischemia models in the rat.

SETTING

University research laboratory.

SUBJECTS

Male, adult Sprague-Dawley rats (300 g).

INTERVENTIONS

Animals were divided into three experimental groups, group A (n = 6, survived for 7 days), 12 mins of hemorrhagic shock; group B (n = 6, survived for 7 days), 5 mins of cardiac arrest; or group C (n = 6, each for 6 hrs, 12 hrs, 1 day, 3 days, and 7 days), 7 mins of hemorrhagic shock and 5 mins of cardiac arrest. Motor deficit of the hind limbs was studied 6 hrs to 7 days after resuscitation. Also, nonoperated animals (n = 6) were used as the control. Histologic analysis (hematoxylin and eosin, Fluoro-Jade B, terminal deoxynucleotidyl transferase- mediated dUTP end-labeling [TUNEL], Klüver-Barrera) and ultrastructural analysis using electron microscopy were performed on samples from the CA1 region of the hippocampus and lumbar spinal cord. Demyelination of the white matter of the lumbar spinal cord was analyzed semiquantitatively using Scion Image software.

MAIN RESULTS

No paraplegic animals were observed in either group A or B. All group C animals showed severe hind-limb paralysis. Severe neuronal damage was found in the CA1 region of the hippocampus in all groups, and the state of delayed neuronal cell death was similar among the three groups. Neuronal damage in the lumbar spinal cord was detected only in group C animals, mainly in the dorsal horn and intermediate gray matter. Demyelination was prominent in the ventral and ventrolateral white matter in group C. A significant difference was observed between control and group C rats with Scion Image software. Ultrastructural analysis revealed extensive necrotic cell death in the intermediate gray matter in the lumbar spinal cord in group C rats.

CONCLUSION

The combination in the global ischemia model (i.e., hemorrhagic shock followed by cardiac arrest) caused severe neuronal damage in the central nervous system. Thereby, hind-limb paralysis after global ischemia might result from spinal cord damage. These results suggest that therapeutic strategies for preventing spinal cord injury are necessary when treating patients with severe global ischemia.

Differences in sensitivity between magnetic motor-evoked potentials and somatosensory-evoked potentials in experimental spinal cord lesions

STUDY DESIGN

Graded posterior spinal cord compression and partial sectioning of the spinal cord were performed, and magnetically induced descending spinal cord potentials were recorded.

OBJECTIVES

To compare the sensitivity of transcranial magnetic motor-evoked potentials in the spinal cord and other spinal cord evoked potentials to spinal cord lesions.

SUMMARY OF BACKGROUND DATA

Somatosensory-evoked potentials have been the standard technique for monitoring spinal cord function during spinal surgery. These potentials, however, do not necessarily reflect descending motor tract function. Transcranial electric or magnetic stimulation for motor-evoked potentials is a more direct measure of motor tract function. However, more research on magnetic motor-evoked potentials is needed.

METHODS

Fifteen adult cats were used. Graded posterior spinal cord compression was performed at L2 in 10 cats, and partial sectioning of the spinal cord was performed at L2 in five cats. The location sequence of lesioning was dorsal column section, dorsal 1/2 section, dorsal 2/3 section, and total spinal cord section. Magnetic motor-evoked potentials were recorded by epidural catheter electrodes placed above at, and below the lesion. Electric motor evoked potentials and spinal and cortical somatosensory-evoked potentials were recorded serially for a comparison of their sensitivity to spinal cord dysfunction.

RESULTS

In posterior spinal cord compression, N1 amplitude of magnetic motor-evoked potentials at and below the lesion decreased after 1 minute of compression with a 70 g weight, and N1 and N2 amplitude disappeared after 1 minute of compression with a 100 to 120-g weight. Electric motor-evoked potentials changed at amplitudes comparable with those shown by magnetic motor-evoked potentials. Spinal somatosensory-evoked potentials showed the most sensitive changes to spinal cord posterior compression and disappeared after 1 minute of compression with 80 g Cortical somatosensory-evoked potentials in five cats were not sensitive enough for spinal cord posterior compression injury and did not disappear even after 1 minute of compression with 120 g. In magnetic motor-evoked potentials, after dorsal hemisectioning of the spinal cord only N3 disappeared; N1 and N2 disappeared after ventral spinal cord sectioning in spinal somatosensory-evoked potentials, amplitudes decreased after dorsal column sectioning, and all negative peaks disappeared after dorsal hemisectioning of the spinal cord.

CONCLUSIONS

Posterior compression injuries are diagnosed more easily with spinal somatosensory-evoked potentials. Motor-evoked potentials were slightly less sensitive, but they were significantly more useful in diagnosing posterior compression injuries than were cortical somatosensory-evoked potentials.

The effect of the platelet derived wound healing formula and the nerve growth factor on the experimentally injured spinal cord

The main purpose of this study is to investigate the effect of platelet derived wound healing formula (PDWHF) and nerve growth factor (NGF) in the treatment of experimental spinal cord injury. PDWHF is a conglomerate of growth factors which include platelet derived growth factor (PDGF), platelet derived angiogenesis factor (PDAF), transforming growth factor-beta (TGF beta) and platelet factor IV (PF4). Complete spinal cord transection was performed at T12 in rats and the treatment of the spinal cord injury was achieved by filling the dead space with type 1 collagen gel impregnated with PDWHF, or with 2.5S-NGF. Controls were treated with only type 1 collagen gel. Animals were sacrificed at 1, 2 or 3 months. Histopathologically, tissue autolysis and cavity formation by phagocytosis expanded 1-3 mm into the cord stumps and the volume of cavitation was less in the two treated groups. In the NGF group, a greater number of surviving nerve cells were observed in this region. Most of the control animals formed only thin, short axonal bundles, however, increased axonal regrowth was noted in animals treated with trophic factors, especially in the NGF group. The NGF group formed thick axonal bundles and abundant neuroma. Increased angiogenesis was observed in the collagen gel matrix and the injured spinal cord parenchyma, in the PDWHF group. Recent studies have shown that mammalian adult CNS possesses the ability for structural and/or functional plasticity following injury under appropriate circumstances. In this in vivo study, exogenous NGF appeared to induce axomal outgrowth and nerve cell survival. PDWHF produced notable angiogenesis which seemed to improve the extracellular microenvironment. This may be important for the delivery of exogenous trophic factors, nutrients and for the changes of extracellular matrices to support nerve cells and axons.

Application of polyvinyl alcohol hydrogel membrane as anti-adhesive interposition after spinal surgery

STUDY DESIGN

Three inflammatory and adhesive changes inside the spinal canal were analyzed histopathologically in cats.

OBJECTIVE

To investigate the usefulness of a polyvinyl alcohol hydrogel sheet as an interposition over the dura to prevent inflammatory and adhesive reaction after laminectomy.

SUMMARY OF BACKGROUND DATA

A major concern after laminectomy is scar tissue formation that may result in extradural compression or make subsequent surgery to the same area difficult and hazardous.

METHODS

Wide laminectomy was performed at L5 in 30 adult cats. The dura was covered with a polyvinyl alcohol hydrogel sheet, free fat graft, or without interposition as a control. Animals were killed at 3 or 12 weeks.

RESULTS

In the control group, adhesion of the exposed dura was apparent. Thick, fibrous connective tissue was observed between the dura and the paravertebral muscles. In the fat graft group, the dura was separated from the scar tissue by living grafted fat. However, the dura was adherent to the grafted fat and fibroblasts migrated into the interstitial space. In the polyvinyl alcohol hydrogel group, only a thin synovium-like layer was formed around the polyvinyl alcohol hydrogel sheet.

CONCLUSIONS

Polyvinyl alcohol hydrogel is made of water and alcohol, and has been shown to be nontoxic to tissues. This is permeable to low molecular weight, but impermeable to large cells such as fibroblasts. Thus, the polyvinyl alcohol hydrogel sheet prevents migration of inflammatory cells and subsequently reduces intraspinal canal scar tissue formation and adhesive reaction. Other beneficial properties are extreme elasticity and low friction, which eliminate mechanical reaction to the spinal cord. The polyvinyl alcohol hydrogel sheet is believed to be useful in eliminating scar tissue formation and does not interfere with the dynamic gliding movement of the spinal cord and nerve roots.

A case of Fabry's disease with granulomatous interstitial nephritis

A 15-year-old boy with proteinuria and hematuria is reviewed in this study. He was first found to have urinary abnormalities at the age of 13 years, and his renal function was exacerbated for a short duration. Renal biopsy was performed to make a histological diagnosis and to establish adequate therapy. Light microscopy showed marked tubulointerstitial inflammation with granulomatous changes, and electron microscopy revealed that numerous osmiophilic inclusions were present in podocytes, mesangial cells, and endothelial cells of the glomeruli and in epithelial cells of the tubules. The alpha-galactosidase activity of lymphocytes from the patient was measured, and the results of this assay indicated that the patient's lymphocytes had a low level of alpha-galactosidase activity. Therefore, the patient was diagnosed as having Fabry's disease with renal dysfunction. This study demonstrated that the onset age of renal insufficiency in Fabry's disease may be earlier than that described previously, and that when granulomatous interstitial nephritis is developed, renal function may deteriorate progressively.

[A case of focal encephalitis with psychological symptoms similar to chorea minor]

We reported a patient with choreic movements, emotional lability, and compulsive-obsessive behavior that developed 4 weeks after onset of fever and lasted for several years. There was no evidence of streptococcal infection or rheumatic fever. T2-weighted MRI showed hyperintense lesions in the bilateral caudate nuclei and putamina. A diagnosis of focal encephalitis was made according to initial fever, convulsion, and CSF pleocytosis. Treatments with haloperidol and prednisolone were effective in some degree. The neurobehavioral syndrome as well as the involuntary movements in this patient can be attributed to the striatal damage, which may disrupt the basal ganglia-limbic-frontal lobe tracts. A symptomatic similarity between the syndrome in this patient and chorea minor suggests a striatal damage in chorea minor, where the causative lesions remain unknown.

X-linked elements associated with negative segregation distortion in the SD system of Drosophila melanogaster

Three elements, M1, M2 and M3, found in a special X chromosome, supp-X(SD), modify the degree and direction of segregation distortion in the SD system of Drosophila melanogaster. The first element, M1, is located between the y and the cv loci, probably close to the y locus. The second element, M2, is located near the cv locus and the third element, M3, is located between the y and the car loci. The M1 element appears to cause a relatively small amount of reduction in the rate of recovery of the SD-72, but not the cn bw, chromosome from SD-72/cn bw males, when raised at 27.5 degrees. The M2 and the M3 elements cause considerable decrease in the recovery rate of the SD-72 chromosome, whereas they increase the recovery rate of the cn bw chromosome. The amount of decrease is nearly the same as the amount of increase for each element. Some type of "switch" mechanism in the directions of distortion is suggested for each of these two elements and their effects appear to be approximately additive.

Temperature sensitivity of negative segregation distortion in Drosophila melanogaster

Previous work has shown that the direction of segregation distortion in the SD (Segregation Distorter) system in Drosophila melanogaster can sometimes be reversed, but this was found only with rather weak distorters and the effect was not large. The present study reports large negative segregation distortion in a strong distorter, SD-72 chromosome. In the presence of a specific X chromosome, supp-X(SD), the proportion, k, of SD-72 chromosomes recovered from the SD-72/cn bw males ranges from 0.99 at 20 degrees to 0.11 at 28.5 degrees, whereas with a standard-X chromosome, k ranges from 0.99 to 0.95 for the same temperature range. The temperature-sensitive period is during spermiogenesis. Using a mating system in which the sperm supply is nearly exhausted, it was shown that the negative distortion at high temperatures is due to an absolute reduction in the number of SD-72 chromosomes and an absolute increase in the number of cn bw chromosomes recovered. After adjusting for non-SD-related temperature effects, the amount of decrease in the number of SD-72 progeny is nearly the same as the amount of increase in the number of cn bw progeny, suggesting that the dysfunction switches from a spermatid carrying one homolog to one carrying the other. Negative distortion requires a radical revision of current hypotheses for the mechanism of segregation distortion and a possible modification of the current model is suggested, based on differential recovery of dysfunction in the two homologs during spermiogenesis.

Electrophysiologic evaluation of intermittent sacral nerve dysfunction in lumbar spinal canal stenosis

Intermittent sacral nerve dysfunction, induced by walking in lumbar spinal canal stenosis, may cause symptoms including hyperesthesia and pain in perineum, urinary bladder incontinence, and penile erection. However, it is difficult to objectively document these symptoms. Evoked external urethral sphincter potentials by conus medullaris stimulation were measured both before walking and after walking in five patients who complained of sexual organ or urinary dysfunction during walking, and were compared with simultaneously induced sacral nerve symptoms. These potentials were also measured during surgery. Sacral nerve symptoms were reproduced by walking 80-350 meters (average 177.5 m). These potentials disappeared in one patient and were decreased in four patients at the time when the claudicant symptoms disabled the patient during walking. The amplitude subsequently recovered in keeping with relief of those symptoms during rest. Monitoring of these potentials during surgery showed an increase of amplitude shortly after the decompression procedure of the cauda equina. In conclusion, this measuring method was valuable as an objective evaluation of intermittent sacral nerve dysfunction in lumbar spinal canal stenosis.

[An acute axonal form of Guillain-Barré syndrome with autoantibody against ganglioside GD1b--a case report]

We reported a 3-year-old boy of an acute axonal form of Guillain-Barré syndrome (GBS) with autoantibody against GD1b ganglioside. A week after an episode of upper respiratory infection, he was hospitalized with a weakness in the lower extremities. Neurological examination revealed facial weakness, restricted extra-ocular movement, hyporeflexia and tetraparesis without any sensory impairment. CSF protein was elevated with normal cell count after the first week of symptoms. Electrophysiological studies demonstrated normal motor nerve conduction velocity and low M potential amplitude. He had been on a respirator for two months. Although he received plasmapheresis in the acute phase, sixteen month after the onset he continued to have distally dominant limb weakness with wasting. Thin-layer chromatogram with immunostaining revealed that serum IgG from this patient reacted with GD1b, but did not react with GM1. Enzyme-linked immunosorbent assay showed that anti-GD1b titer (IgG) decreased concurrently with the clinical improvement. There have been several reports of an acute axonal form of GBS with antibody to GM1. GD1b, as well as GM1, seems to be a target pathogenic antigen in motor axon disorders.

Immunohistochemical identification of muscle fiber types in normal and degenerated muscles

Myosin ATPase reactions are generally used to differentiate between muscle fibers. However, those reactions have disadvantages including the need for delicate pH control and preincubation under non-physiological pH. Furthermore enzyme activity is only an indirect reflection of myofilament characteristics. In this study, an immunohistochemical method with anti-slow and anti-fast myosin heavy chain antibodies was used to observe: 1) whether muscle fiber types could be distinguished in degenerated muscles, 2) immunoreactivity of type 2C fibers in denervated muscles, and 3) discrepancies in structural disorders. Thirty one muscle biopsies which included neurogenic, myogenic, and control muscles were examined. Muscle fiber types were recognized in normal and in severely degenerated muscles. Type 2C muscle fibers were not necessarily constantly immunoreactive to both anti-slow and anti-fast myosin antibodies. In some targetoid fibers sites with absence of myosin ATPase activity had the same or rather higher immunoreactivity. Some muscle fibers undergoing fiber-type transformation showed discrepancies in reactivity between enzyme- and immuno-reactivity. This immunohistochemical method is capable of observing changes of muscle fibers during denervation, reinnervation, and also sports activity.

In vivo angiogenesis by platelet-derived wound-healing formula in injured spinal cord

In vivo angiogenesis was investigated using platelet-derived wound-healing formula (PDWHF) in the injured cat spinal cord. Twenty-two gauge teflon sheaths, which had been coated with PDWHF-Hydron or only with Hydron, were inserted into the spinal cords of cats and the injured cats were maintained for 3 weeks. Selection of PDWHF-Hydron or Hydron was double blinded. The PDWHF-Hydron group showed notable neovascularization as well as dilation around the injury site, and this was statistically significant when compared to the control group. PDWHF seems to play a role in the healing processes of spinal cord injury and may have important interactions with other growth factors and in particular neurogenic growth factor.

Open total dislocation of the talus with extrusion (missing talus): report of two cases

Two different methods of treatment for open dislocation of the extruded talus without soft tissue attachments (missing talus) were examined. In case 1, a 20-year-old man sustained an open total dislocation of the talus due to a motorcycle accident. The missing talus was found within 3 hr and replaced after thorough washing and debridement. Weightbearing was permitted at 20 weeks; however, the density of the talar body increased in the x-ray and nonweightbearing status was resumed. Reexamination at 2 1/2 years revealed that there was joint space narrowing on the x-ray and decreased pain with ambulation; the patient had returned to his job. In case 2, a 26-year-old man sustained an open total dislocation of the talus with a severe crush wound and impaired circulation to the foot. After thorough washing and debridement of the wound, the calcaneus and distal end of the tibia were aligned. The missing talus was found 3 days later, but not replaced. Weightbearing was allowed on the affected foot at 2 months; however, the patient felt pain at the joint surfaces and arthrodesis was consequently performed. At 2 1/2 years, the patient had a 4.0-cm leg length discrepancy in the involved extremity, but felt no pain when walking. Although reduction of the talus is ideal to preserve function and length of the extremity, several complications can occur. A review of literature on open total dislocation of the talus with extrusion was performed.

Gly145 to Arg substitution in HBs antigen of immune escape mutant of hepatitis B virus

A Japanese child born to an HBeAg-positive carrier mother received anti-HBs immunoglobulins and a plasma-derived HBs vaccine with a poor anti-HBs-antibody response. The child, who is now 3 years old, is presently suffering from chronic hepatitis with unusual serological findings that are positive for HBsAg, anti-HBs and HBeAg, since being infected with a measles virus at 12 months of age. The nucleotide sequences of the S region of HBV DNA obtained from the patient, the mother and an HBeAg-positive brother were completely identical except for one nucleotide at position 587 (mother and brother: guanosine, patient: adenosine), giving an amino acid change: Gly - greater than Arg at position 145 of the major HBs protein.

The effect of growth factor formula (platelet derived wound healing formula) in experimental spinal cord injuries

The main purpose of this study was to investigate the usefulness of platelet derived wound healing formula (PDWHF) in the treatment of experimentally induced spinal cord injuries in cats. The injury model in ten adult cats consisted of the placement of three 22-gauge Teflon catheter sheaths into the spinal cord at the L2 level. Treatment consisted of coating these sheaths with PDWHF in Hydron. Three animals were used as controls. In the 7 remaining cats, treatment was double blinded. Cats were sacrificed at 3 weeks after injury and injured spinal cord segments were excised for histologic evaluation. Electrophysiologic and clinical motor function were evaluated throughout a period of observation. Evoked potentials in both the treated and control groups indicated incomplete spinal cord lesions due to insertion of the needles. There did not appear to be any significant improvement or difference in the evoked response and clinical function as a result of treatment with PDWHF. The histological findings in the PDWHF-treated group showed significant new vessel formation as well as dilation and around the injury site. This neovascularization, both qualitative and quantitative, was noted in the treatment group. This information, with a limited injury and very simple delivery system for growth factor, would suggest there is definite neovascularization occurring as a result of this treatment and this may be useful in the subsequent wound healing response such as axonal growth and scar tissue formation.

Long-term morphology of spastic or flaccid muscles in spinal cord-transected rabbits

Despite difficulty in long-term maintenance of spinalized rabbits, muscular pathologic changes in chronic spinalized rabbits could be observed for a period of four weeks. Rabbits were prepared by spinal cord transection at T10 (spastic paralysis) or by spinal cord removal below L7 (flaccid paralysis). Spastic preparations showed hind-limb spasticity and reflex incontinence one to two days after operation. Hypertrophic fibers began to appear in spastic muscles after two weeks. This hypertrophy, thought to be caused by phasic repetitive contraction, was verified by electron microscopy to be different from normal exercise hypertrophy. Flaccid preparations maintained hind-limb flaccidity and overflow incontinence. In flaccid muscle, marked muscle fiber necrosis indicated rapid atrophy. Spinal deformity and joint contracture inactivate spinalized rabbits, and cause pressure sores. However, feeding assistance and avoidance of complications make long-term maintenance possible.

Negative segregation distortion in the SD system of Drosophila melanogaster: a challenge to the concept of differential sensitivity of Rsp alleles

Current models of segregation distortion based on previous experimental results predict that, in the Sd heterozygous Rspi/Rsps male, the chromosome carrying the sensitive Rsps allele is distorted or transmitted in a frequency smaller than that of the expected Mendelian 0.5 relative to the chromosome carrying the insensitive Rspi allele. The present study presents a case where this does not occur, that is, when the genotype of the males is supp-X(SD)/Y; Sd E(SD)Rspi M(SD)+/Sd+ E(SD)+ Rsps M(SD)+ where supp-X(SD) is an X chromosome carrying a strong suppressor or suppressors of SD activity and SD+ E(SD)+ Rsps M(SD)+ is the standard cn bw chromosome. Following the "inseminated female transfer" procedure, young males of the above genotype carrying the standard-X instead of the supp-X(SD) chromosome show k values for the SD chromosome (frequencies of the SD chromosome recovered among progeny) of about 0.75, but with the supp-X(SD) chromosome, the k values are reduced to 0.36-0.41. Several possibilities other than the mechanism of segregation distortion to explain the reduced k values are ruled out. The occurrence of "negative segregation distortion" is clearly demonstrated, where the chromosome carrying the Rspi allele is distorted but the chromosome with the Rsps allele is not. This result requires a major modification of the current models or even a new model for the mechanism of segregation distortion to accommodate Rsp allele sensitivity or insensitivity. The present study also shows that males of the genotype, Sd Rspss M(SD)+/Sd+ Rspss M(SD), are almost completely sterile, but their fertility is considerably increased when SD activity is suppressed by the presence of the supp-X(SD) chromosome. This result suggests that the amount of the Sd product is not limited with respect to the interacting sites available, that is, the amount is large enough to interact with both of the Rspss alleles.

A possible case of negative segregation distortion in the SD system of Drosophila melanogaster

Models proposed to explain segregation distortion in Drosophila melanogaster are based partly upon the observation that, in the Sd heterozygous Rspi/Rsps male, the chromosome carrying the sensitive Rsps allele is distorted, but the chromosome carrying the insensitive Rspi allele is not. The results of the present study suggest that this may not always be the case. Under a certain genotypic condition, the chromosome carrying the Rsps allele can be transmitted to the progeny in frequencies of more than 0.5 (about 0.6), or correspondingly, the chromosome carrying the Rspi allele may be distorted with respect to the one with the Rsps allele. Thus, the relative sensitivity and insensitivity of the two Rsp alleles in a male are not absolute, but relative; and they may be reversed depending upon the residual genotype. If this is true, a major modification of the current models or a proposal of an entirely new model may become necessary to explain the mechanism of segregation distortion satisfactorily.

Long term observation of micturition by spinal cord transected rabbits

Neurogenic bladder was observed in chronic spinalized animals. Since these animals are difficult to maintain for long periods, there are few reports of systemic study of these preparations. We have recently observed micturition by spinalized rabbits over a period of 4 weeks. In thoracic or lumbar spinalized rabbits, urinary bladder contraction and external urethral sphincter activity were initially recorded from 1-2 days postoperative. Contraction coincided with appearance of hind-limb spasticity. This micturition was the so-called detrusor-external urethral sphincter dyssynergy with residual urine. In sacral spinalized rabbits, no micturition reflex, external urethral sphincter activity, or hind-limb spasticity were observed and the flaccid state continued for 4 weeks. It is suggested that a segmental micturition reflex pathway exists initially in the rabbit sacral cord, because reappearance of the micturition reflex was extremely quick (1-2 days) compared to that of cats (2-3 weeks). Animal hypnosis enabled immobilization during measurement without anesthetic or decerebration. Chronic spinalized rabbits, which are very intolerant to spinal damage, can be maintained alive by intensive care at and post operation and are useful for systemic study of spinal cord injury.

Regional lung perfusion and ventilation with radioisotopes in cervical cord-injured patients

In general, cervical cord-injured patients present with restrictive pulmonary dysfunction resulting from paralysis of the intercostal muscles. Vital capacity frequently decreases below 50% of that in normal subjects, and their respiratory pattern frequently includes paradoxical movement in which the intercostal spaces sink and the abdomen distends at inspiration. Ventilation scintigraphy using Xe-133 and pulmonary perfusion scintigraphy using Tc-99m macroaggregated albumin (MAA) were performed on nine cervical cord-injured patients and four normal subjects to investigate regional lung functions in the cervical cord-injured patients. Pulmonary perfusion scintigraphy, in which measurement was made in the supine position, revealed no differences between the patients and the normal subjects. The inhomogeneous ventilation/perfusion distribution was presumed to have resulted from change in regional intrapleural pressure due to paradoxical movement of the thoracic cage. Washing and washout times were prolonged by paralysis of the intercostal muscles. These phenomena were particularly apparent in the upper and middle lung regions where compensating action by movement of the diaphragm is small.

Genetics of factors affecting the life history of Drosophila melanogaster. I. Female productivity

Starting from four basic strains of Drosophila melanogaster, two laboratory strains (cn bw, Tokyo) and two isofemale lines (B-102, B-103) originated from a wild population in Texas, we constructed by repeated backcrosses through females for 20 or more generations a total of 16 strains of all possible combinations between the chromosome sets and cytoplasmic classes. Females from these 16 synthesized strains were then examined for their reproductive performance during their entire life span.---The chromosome set from the cn bw strain was found to associate with the highest female productivity when the age of females was very young, but these females ceased their reproduction and died relatively earlier, resulting in a smaller number of total progeny. The B-102 and B-103 chromosome sets, on the other hand, were associated with the lowest productivity when the females were young, but they lived and continued reproduction longer, resulting in a larger number of total progeny. The Tokyo chromosome set was associated with female productivity intermediate between the other two groups.---Cytoplasmic factors were found to affect the productivity of young females, with the cytoplasm from the cn bw strain associated with the highest productivity. Longevity was not cytoplasmically affected.---There was a clear interaction in female productivity between the Tokyo chromosome set and the cytoplasm from the Texas isofemale lines; the lifetime female productivity, as well as longevity, associated with the Tokyo chromosome set was found to increase considerably when it was substituted into the cytoplasm of the Texas isofemale lines. This chromosome-cytoplasm interaction appeared to be independent of the two systems of hybrid dysgenesis.

[Prevention of postoperative infection following cardiac catheterization in pediatric field. Study of air-borne bacteria in X-ray room and evaluation of an antibiotic used for prevention of postoperative infection]

As part of preventive measures against postoperative infection following cardiac catheterization in infants with cardiac diseases, especially falling bacteria in X-ray room was studied. Moreover, a synthetic penicillin, ticarcillin (TIPC), was used as preventive antibiotic against postoperative infections due to falling bacteria which probably contaminate the air in the X-ray examination room, and the efficacy and side effects of the drug were observed. As result, coagulase-negative Staphylococcus was detected the most, followed by Micrococcus and then by fungus. The number of these 3 organisms corresponded to 90.3% of the total number of falling bacteria detected during operation. The number of falling bacteria during operation was 5.1 times larger than that before operation. Taking into account normal flora of skin, falling bacteria present in the X-ray room and causative organisms of bacterial endocarditis, TIPC was administered to 30 cases intravenously 5 times at a dose of 30 mg/kg every 8 hours for the purpose of preventing possible postoperative infections following cardiac catheterization. The drug was effective to prevent such infections in all cases. No side effects were noted in any case, in peripheral blood and hepatic function tests and other observations.

INTERACTION IN TRANSMISSION FREQUENCY BETWEEN THE SECOND AND THE THIRD CHROMOSOMES IN DROSOPHILA MELANOGASTER

Wild second and third chromosomes from isofemale lines established from wild-inseminated females captured in natural populations of Drosophila melanogaster in Hawaii, New York, North Carolina and Texas were made heterozygous in males with marked second and third chromosomes from a laboratory strain, and the transmission frequencies of the wild second (= k  2) and the third (= k  3) chromosomes from the heterozygous male parents were measured. Based upon the preliminary tests of k  2, the isofemale lines were classified into two groups; group A included those lines showing average k  2 values considerably smaller than the Mendelian expectation of 0.5, and group B included those lines showing average k  2 values close to 0.5. Effects of the wild second chromosomes on k  2 in group A were suppressed (the average k  2 values increased) by the presence of the wild third chromosomes, whereas the wild second chromosomes in this group, in turn, caused a decrease in k  3 of the wild third chromosomes. The intensities of the observed effects were more or less comparable in their absolute values, and these phenomena do not appear to be due to differential viabilities of zygotes. No such interaction was observed between the wild second and third chromosomes in group B. An extention of the model of the Segregation Distorter system of D. melanogaster, as well as a model based upon the P-M system of hybrid dysgenesis, may explain the observed results.

SUPPRESSOR SYSTEMS OF SEGREGATION DISTORTER (SD) CHROMOSOMES IN NATURAL POPULATIONS OF DROSOPHILA MELANOGASTER

Several natural populations of D. melanogaster were investigated for the presence (or absence) of the Segregation Distorter (SD) chromosomes and their suppressor systems. The SD chromosomes were found, at frequencies of a few percent, in two independent samples taken in different years from a Raleigh, North Carolina, population, whereas no SD chromosomes were found in samples collected from several populations in Texas. The populations in these localities were found to contain suppressor X chromosomes in high frequencies (75% or higher). They also contained relatively low frequencies of partial suppressor or insensitive second chromosomes of varying degrees, but completely insensitive second chromosomes were practically absent in all populations examined. The frequencies of suppressor X chromosomes, as well as those of the partially insensitive or suppressor second chromosomes, were the same among the populations investigated. This suggests the possibility that the development of a suppressor system of SD in a population could be independent of the presence of an SD chromosome. Segregation distortion appeared to be occurring in natural genetic backgrounds, but the degree of distortion varied among males of different genotypes. There were many instances in which the SD chromosomes showed transmission frequencies from their heterozygous male parents that were smaller than 0.6 and, in several cases, even smaller than 0.5. The presence of a recessive suppressor, or suppressors, of SD in natural populations was suggested.

A two-generation study of human sex-ratio variation

We report here the first vertical population study of human sex-ratio variation. Sex-ratio data for 2 generations from Akita, Japan, have been analyzed. Parental age, birth order, sequences of the sexes at birth, and generations have no statistically significant effect on sex ratio. There is a slight excess of males at birth, as is typical for human sex-ratio studies. There is evidence of sex-ratio-dependent family planning. An analysis of vertical transmission of sex-ratio modifying factors that excludes effects of birth order in both the parental and offspring generations has detected a marginally significant paternal effect. Genetic variability of the sex ratio, if present at all, is of a very minor magnitude.

Gametic frequency of second chromosomes of the T-007 type in a natural population of Drosophila melanogaster in Texas

The T-007 second chromosome, which was isolated from a natural population of Drosophila melanogaster in south Texas in 1970, is known to show, when made heterozygous in males with a standard cn bw second chromosome, a transmission frequency (k) of 0.35-much lower than the theoretically expected 0.5. Natural populations of this species in Texas contain second chromosomes that, against the standard cn bw genetic background, are associated with distorted transmission frequencies comparable to that of the T-007 chromosome. In order to explain how such chromosomes can persist in natural populations in nontrivial frequencies, it has been postulated that, although such chromosomes show reduced k values when tested under the genetic background of a laboratory stock such as cn bw, they may show, on the average, k values larger than 0.5 under natural genetic backgrounds. If this were true, the frequency of chromosomes of the T-007 type (T chromosomes) should be higher in male than in female gametes under natural genetic backgrounds. The present study was conducted to examine this possibility. The results clearly showed that the frequency of such chromosomes was much higher among male than among female gametes, and that the transmission frequency of this type of chromosome was higher than 0.5 under natural genetic backgrounds. These results suggest that T chromosomes behave like Segregation Distorter (SD) chromosomes in natural populations of this species in Texas. A possible relationship between T-007 and SD chromosomes is suggested.

Heterochromatic recombination in germ cells of Drosophila melanogaster females

Heterochromatic recombination in germ cells was found to occur in females of Drosophila melanogaster having a specific genotype. Results of the present study can be summarized as follows: (1) The frequency of heterochromatic recombination decreases consistently and markedly as the female ages. (2) The female that induces heterochromatic recombination is associated with reduced number of progeny when she is young, but as she gets older, the number of progeny increases, approaching that of the normal female. The reduction in the number of progeny is due to unhatchability of eggs produced, not to reduced egg laying. (3) Cytoplasmic factors affect the above two traits. These traits seem to be due to interaction between chromosomal and cytoplasmic elements. (4) These traits are not expressed in males. (5) The increase in recombination frequency seems to be limited to the centric heterochromatin.--It is suggested that heterochromatic recombination is one of the traits associated with the I-R system of hybrid dysgenesis in D. melanogaster.

A MODIFIED MODEL OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

Elements of the Segregation Distorter (SD) system of Drosophila melanogaster, Sd and Rsp, were analyzed and the following points were established: (1) The model of multiple alleles at the Rsp  s locus proposed by MARTIN and HIRAIZUMI (1979) is supported by our observations. (2) A modifier of SD, tentatively symbolized M(SD), was found close to cn (2R-57.5). (3) Sd heterozygous males were found to show, under certain genotypic condition, almost complete sterility.——Based upon these observations, the following modified model of segregation distortion is proposed: (1) The M(SD) locus produces a multimeric repressor protein that binds to the Rsp locus as a necessary condition for normal spermiogenesis. M(SD) homozygotes produce a repressor M(SD)/M(SD); whereas, a homozygote for its normal allele M+(SD) produces a M+(SD)/M+(SD) repressor. M(SD)/M+(SD) heterzygotes produce a M(SD)/M+(SD) repressor. (2) The Sd locus produces a certain product that, like an inducer in the lactose system of E. coli, tends to bind with the repressor complexed with the Rsp locus. This binding disrupts the repressor-Rsp complex, causing Rsp locus to be turned on. The product of Rsp transcription, in turn, results in sperm dysfunction. (3) Rsp  i, an allele of Rsp, has a strong complexing affinity with the repressor such that the Rsp  i-repressor complex is "resistant" to the inducing activity of Sd product. Rsp  s, on the other hand, has a weaker complexing affinity than that of Rsp  i, and the degree of affinity varies among different Rsp  s alleles.——A possible extension of the above model is discussed.

A model of the negative correlation between male recombination and transmission frequency in Drosophila melanogaster

A model is proposed to account for the phenomenon of negative correlation between male recombination (theta) and transmission frequency (kappa) in Drosophila melanogaster. The model assumes that, in some stage or stages of development, the male recombination elements cause a particular event that does not occur in normal males and that this event, in turn, induces with certain probabilities male recombination and/or sperm dysfunction. The regression equations of theta on kappa predicted by the model were compared with those actually observed. There was generally excellent agreement between them.

ON THE MODELS OF SEGREGATION DISTORTION IN DROSOPHILA MELANOGASTER

The Segregation Distorter system of Drosophila melanogaster consists of two major elements, Sd and Rsp. There are two allelic alternatives of Rsp—sensitive (Rsp8) and insensitive (Rspi); a chromosome carrying Rspi is not distorted. According to the model proposed by HARTL (1973), these two elements interact to cause segregation distortion. For a sperm to complete the maturation process, it is assumed that the Rsp locus has to be complexed with the product of the Sd locus. This product is assumed to be a multimetric regulatory protein. Three kinds of regulatory multimers may be distinguished: Sd+/Sd+, which is assumed to complex with both Rsp8 and Rspi; Sd+/Sd heteromultimers, which complex preferentially with Rspi; and Sd/Sd hmomultimers, which complex with neither Rsp8 nor Rspi. Most of the regulatory protein in the Sd+/Sd heterozygous male is assumed to be the Sd+/Sd heteromultimer. ——Some modifications of HARTL'S model were made by GANETZEY (1977). Rather than the binding of a product of Sd at the Rsp locus being a necessary condition for normal spermigenesis, this binding causes sperm dysfunction. It is assumed that the product of Sd complexes more readily with Rsp8 than with Rspi and that the amount of Sd product is limited with respect to the number of binding sites available. No function is ascribed to the Sd+ locus. In order to explain reduced male fertility of some genotypes, GANETZKY further assumes that the Sd product, when not competed for by an Rsp8 locus, can bind to an Rspi locus.——Two consequences of these models were criticically examined: according to these models (1) an Sd Rsp8/Sd+ RspS male should not show any segregation distortion, and (2) an Sd Rsps/Sd Rsp8 male should show much reduced fertility, if not complete sterility.—The results of the present study bear on these two points. (1) Rsp8 locus seems to consist of multiple alleles, each having a different degree of ability to interact with the product of the Sd locus. An Sd Rsp8/Sd+RspS male shows a certain degree of segregation distortion when the two RspS alleles are different, but it shows a normal Mendelian segregation ratio when the Rsp8 alleles are homozygous. The first prediction of the models is supported by actual observation when the two Rsps alleles are the same. (2) There is a suggestion of slight reduction in fertility, but generally Sd Rsp8/Sd Rsp8 males are quite fertile. Thus, the second prediction is not supported by actual observation. The mechanism of segregation distortion is still open for future studies.

A new method to distinguish between meiotic and premeiotic recombinational events in Drosophila melanogaster

A new method is proposed to distinguish between meiotic and premeiotic exchange events in Drosophila melanogaster males associated with male recombination activities. The method was applied to data that have accumulated in this laboratory during the past five years, and it was concluded that a large fraction, perhaps the overwhelming majority, of the male recombinants were due to exchange events that took place before meiosis.

THE RELATIONSHIPS AMONG TRANSMISSION FREQUENCY, MALE RECOMBINATION AND PROGENY PRODUCTION IN DROSOPHILA MELANOGASTER

The T-007 second chromosome line, which was originally isolated in 1970 from a natural population of Drosophila melanogasterat Harlingen, south Texas, has previously been shown to be associated with several unusual genetic phenomena. In the present study, two characteristics, distorted transmission frequency and male recombination, were analyzed in relation to the progeny production of T-007 heterozygous individuals. The following points were established: (1) Distorted transmission frequency in the T-007 heterozygous male was mainly due to "elimination" of T-007 chromosomes among the progeny, while no such elimination occurred for the normal partner chromosome. (2) Transmission frequency and progeny production of the T-007 heterozygous females were normal, or at least almost normal. (3) The frequency of male recombination increased with an increasing degree of distortion. This was due to an increased number of recombinants produced per male and to a decreased number of progeny receiving the T-007 chromosome.

Elements causing male crossing over in Drosophila melanogaster

A second chromosome line of Drosophila melanogaster (Symbol: T-007) has previously been shown to be responsible for the induction of male recombination. In the present investigation, the genetic elements responsible for this phenomenon have been partially identified and mapped. A major element (Symbol: Mr, for Male recombination) locates on the second chromosome between the pr (2L-54.4) and c (2R-75.5) loci and is responsible for the large majority of male recombination. In addition, there appear to be "secondary elements" present which have the ability to induce male recombination in much reduced frequencies and which are diluted out through successive back-cross generations when Mr is removed by recombination. The possible nature of these "secondary elements" is discussed.

Mutation induction in the male recombination strains of Drosophila melanogaster

One group of the second chromosome lines isolated from a southern Texas population of Drosophila melanogaster, which has been known to show relatively high frequencies of male recombinations, was found to increase the frequency of sex-linked recessive lethal mutations from a control frequency of 0.18% to 1.63%. The second group, which showed a very much reduced frequency of male recombinations, was found to cause a slight increase to 0.48%, although it was not statistically significant. The first group was also tested for the recessive lethal mutation frequency in the second chromosome; the frequency increased from a control frequency of 0.28% to 2.82%. Mapping of a portion of the sex-linked lethals indicated a distribution along the entire X chromosome, although there was a tendency of clustering towards the tip of the X chromosome. One sex-linked lethal line so far tested was found to be associated with an inversion (approximate breakpoints, 14A-18A). It was suggested that the element causing male recombination might be similar to the hi mutator gene studied earlier by Ives (1950).