Evaluating the activity of N-89 as an oral antimalarial drug

Despite the recent progress in public health measures, malaria remains a troublesome disease that needs to be eradicated. It is essential to develop new antimalarial medications that are reliable and secure. This report evaluated the pharmacokinetics and antimalarial activity of 1,2,6,7-tetraoxaspiro[7.11]nonadecane (N-89) using the rodent malaria parasite Plasmodium berghei in vivo. After a single oral dose (75 mg /kg) of N-89, its pharmacokinetic parameters were measured, and t1/2 was 0.97 h, Tmax was 0.75 h, and bioavailability was 7.01%. A plasma concentration of 8.1 ng/ml of N-89 was maintained for 8 h but could not be detected at 10 h. The dose inhibiting 50% of parasite growth (ED50) and ED90 values of oral N-89 obtained following a 4-day suppressive test were 20 and 40 mg/kg, respectively. Based on the plasma concentration of N-89, we evaluated the antimalarial activity and cure effects of oral N-89 at a dose of 75 mg/kg 3 times daily for 3 consecutive days in mice harboring more than 0.5% parasitemia. In all the N-89- treated groups, the parasites were eliminated on day 5 post-treatment, and all mice recovered without a parasite recurrence for 30 days. Additionally, administering oral N-89 at a low dose of 50 mg/kg was sufficient to cure mice from day 6 without parasite recurrence. This work was the first to investigate the pharmacokinetic characteristics and antimalarial activity of N-89 as an oral drug. In the future, the following steps should be focused on developing N-89 for malaria treatments; its administration schedule and metabolic pathways should be investigated.

Formulation and evaluation of the antimalarial N-89 as a transdermal drug candidate

The discovery of new effective and safe antimalarial drugs is mandatory. In this report, we formulate and evaluate transdermal (td) 1,2,6,7-tetraoxaspiro[7.11]nonadecane (N-89) using the Plasmodium berghei rodent malaria parasite in vivo model. The selected solvent for the ointment type of td N-89 was polyethylene glycol (PEG) [PEG400:PEG 4000 = 8:1 (v/w)]. We tested different application areas of 4, 6, and 8 cm² on the shaved backs of mice. Pharmacokinetic (PK) analysis of N-89 parameters after a single 4 cm² transdermal application revealed that the T_max was 2 h, the T_1/2 was 1.9 h, and the AUC was 1951.1 ng^.h/mL. More than 10 ng/mL of plasma concentration was maintained for 12 h. The ED₅₀ values for the 4, 6, and 8 cm² application areas in a 4-day suppressive test were 18.9, 25.1, and 26.8 mg/kg, respectively. We additionally tested the cure effect of td N-89 in mice at a dose of 60 mg/kg, twice daily for 4 days at 0.2% parasitemia. Parasites disappeared following day 7 post-treatment in all td N-89 treated groups. Mice were cured without any parasite recurrence or dermal irritation. In conclusion, this study determined for the first time the PK parameters and effect of a new ointment type of td N-89. This suggests that transdermal treatment with N-89 is an effective and safe alternative route for the treatment of malaria, especially in children.

Pioneer Use of Antimalarial Transdermal Combination Therapy in Rodent Malaria Model

We have previously reported 1,2,6,7-tetraoxaspiro [7.11]nonadecane (N-89) as a promising antimalarial compound. In this study, we evaluated the effect of transdermal therapy (tdt) of N-89 in combination (tdct) with other antimalarials as an application for children. We prepared ointment formulas containing N-89 plus another antimalarial drug, specifically, mefloquine, pyrimethamine, or chloroquine. In a 4-day suppressive test, the ED50 values for N-89 alone or combined with either mefloquine, pyrimethamine, or chloroquine were 18, 3, 0.1, and 3 mg/kg, respectively. Interaction assays revealed that N-89 combination therapy showed a synergistic effect with mefloquine and pyrimethamine, but chloroquine provoked an antagonistic effect. Antimalarial activity and cure effect were compared for single-drug application and combination therapy. Low doses of tdct N-89 (35 mg/kg) combined with mefloquine (4 mg/kg) or pyrimethamine (1 mg/kg) gave an antimalarial effect but not a cure effect. In contrast, with high doses of N-89 (60 mg/kg) combined with mefloquine (8 mg/kg) or pyrimethamine (1 mg/kg), parasites disappeared on day 4 of treatment, and mice were completely cured without any parasite recurrence. Our results indicated that transdermal N-89 with mefloquine and pyrimethamine provides a promising antimalarial form for application to children.

Antimalarial effect of synthetic endoperoxide on synchronized Plasmodium chabaudi infected mice

The discovery of new antimalarial drugs can be developed using asynchronized <i>Plasmodium berghei</i> malaria parasites in vivo in mice. Studies on a particular stage are also required to assess the effectiveness and mode of action of drugs. In this report, we used endoperoxide 6-(1,2,6,7-tetraoxaspiro [7.11] nonadec-4-yl) hexan-1-ol (N-251) as a model antimalarial compound on <i>P. chabaudi</i> parasites. We examined the antimalarial effect of N-251 against ring-stage- and trophozoite-stage-rich <i>P. chabaudi</i> parasites and asynchronized <i>P. berghei</i> parasites using the 4-day suppressive test. The ED₅₀ values were 27, 22, and 22 mg/kg, respectively, and the antimalarial activity of N-251 was verified in both rodent malaria parasites. To assess the stage-specific effect of N-251 in vivo, we evaluated the change of parasitemia and distribution of parasite stages using ring-stage- and trophozoite-stage-rich <i>P. chabaudi</i> parasites with one-day drug administration for one life cycle. We discovered that the parasitemias decreased after 13 and 9 hours post-treatment in the ring-stage- and trophozoite-stage-rich groups, respectively. Additionally, in the ring-stage-rich N-251 treated group, the ring-stage parasites hindered trophozoite parasite development. For the trophozoite-stage-rich N-251 treated group, the distribution of the trophozoite stage was maintained without a change in parasitemia until 9 hours. Because of these findings, it can be concluded that N-251 suppressed the trophozoite stage but not the ring stage. We report for the first time that N-251 specifically suppresses the trophozoite stage using <i>P. chabaudi</i> in mice. The results show that <i>P. chabaudi</i> is a reliable model for the characterization of stage-specific antimalarial effects.

Accuracy of Lateral Mass Screw Insertion during Cervical Spine Surgery without Fluoroscopic Guidance and Comparison of Postoperative Screw Loosening Rate among Unicortical and Bicortical Screws Using Computed Tomography

Introduction

Pedicle screws (PSs) or lateral mass screws (LMSs) are used in posterior cervical spine fixation. The former are more firmly fixed but are associated with the risk of neurovascular injury and should be inserted using intraoperative imaging or navigation, which may prolong the surgical duration and is not feasible in all hospitals. This prospective clinical study aimed to evaluate the outcomes of LMS insertions without fluoroscopic guidance and screw loosening rates at 6 months postoperatively using computed tomography (CT).

Methods

We examined 38 patients who underwent posterior cervical spine fusion using 206 LMSs in the C3-C6 range between January 2018 and July 2021. The direction of screw insertion followed the Magerl method, and we inserted screws as bicortically as possible without intraoperative imaging. The screw position was examined using CT at 1 week postoperatively. Screw insertion angles, bicortical insertion rate, facet violation, and neurovascular injury were evaluated. Screw loosening with unicortical and bicortical screws (US and BS, respectively) was investigated using CT at 6 months postoperatively.

Results

The average LMS length was 14.1 mm. The average axial and sagittal angles were 33.9° and 29.2°, respectively. Among the 206 LMSs inserted, 167 were BS; of these, 94.6% had screw length protrusion of 0-2 mm. Facet violation was observed in 3.4% of all screws but without neurovascular injury. Six months postoperatively, loosening of 25 screws (12.1%) occurred, including 17 (18.3%) USs and 8 (8.39%) BSs. The screw loosening rate was significantly higher in US than for BS (43.6% [17/39] vs. 4.8% [8/167], P<0.01).

Conclusions

Over 80% of LMSs were inserted bicortically without intraoperative imaging. By devising the screw length selection process, we inserted for screw loosening was more common in US and more likely at the fixed end.

Minimally invasive 360-degree pelvic ring fixation using a combination of crab-shaped fixation and pelvic internal fixator for unstable pelvic ring fracture: A case report

Surgery with both anterior and posterior fixation is recommended for unstable pelvic ring fractures; nonetheless, the surgical method remains controversial. Crab-shaped fixation is a minimally invasive and strong posterior fixation method using spinal instruments that can reduce vertical dislocations. The use of pelvic internal fixator as a minimally invasive anterior fixation method has been reported. It is recommended in cases where there is an open wound in the lower abdomen or damage to the pelvic organs. Conversely, to the best of our knowledge, there has been no report on the combined use of crab-shaped fixation and pelvic internal fixator to date. We performed a minimally invasive 360-degree fixation using a combination of crab-shaped fixation and pelvic internal fixator for an unstable pelvic ring fracture (AO-C2) and sacral fracture (Denis zone II) with 15-mm vertical dislocation. The sacral fracture was accompanied by a large bone fragment in the spinal canal, which was suspected to have caused neuropathy. Therefore, in addition to posterior fixation, we performed decompression and removed the bone fragment. Postoperative computed tomography revealed that the sacral vertical dislocation was reduced to 7.5 mm. The patient started getting out of bed on postoperative day 2. His neuropathy improved after surgery. Owing to abdominal discomfort, pelvic internal fixator was extracted at 3 months postoperatively. Bone fusion was completed, and posterior fixation was removed at 9 months postoperatively. Two years after, the patient walks independently and has returned to work. Minimally invasive 360-degree pelvic ring fixation is a treatment option for an unstable pelvic ring fracture (AO-C2).

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CSF360 is a modified CSF surgical technique.

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Free bone fragment and 360° pelvic ring fixation CSF and INFIX were performed.

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Unstable pelvic ring fractures can be fixed to 360° of circumference.

Electric Quadrupolar Contributions in the Magnetic Phases of UNi_{4}B

We present acoustic signatures of the electric quadrupolar degrees of freedom in the honeycomb-layer compound UNi_{4}B. The transverse ultrasonic mode C_{66} shows softening below 30 K both in the paramagnetic phase and antiferromagnetic phases down to ∼0.33  K. Furthermore, we traced magnetic field-temperature phase diagrams up to 30 T and observed a highly anisotropic elastic response within the honeycomb layer. These observations strongly suggest that Γ_{6}(E_{2g}) electric quadrupolar degrees of freedom in localized 5f^{2} (J=4) states are playing an important role in the magnetic toroidal dipole order and magnetic-field-induced phases of UNi_{4}B, and evidence some of the U ions remain in the paramagnetic state even if the system undergoes magnetic toroidal ordering.

Minimally invasive spinopelvic "crab-shaped fixation" for unstable pelvic ring fractures: technical note and 16 case series

Background

Unstable sacral fractures are high-energy injuries and comprise polytrauma. Internal fixation to enable withstanding vertical loads is required to get up early from the bed after an unstable sacral fracture. We developed a new minimally invasive surgical (MIS) procedure for unstable pelvic ring fractures and reported it in Japanese in 2010. We presented our minimally invasive surgical technique of crab-shaped fixation for the treatment of unstable pelvic ring fractures and report on its short-term outcomes.

Methods

Sixteen patients with unstable pelvic ring fractures (AO types C1, 2, and 3) were treated using crab-shaped fixation. All procedures were performed with the patient in the prone position through 5-cm skin incisions created bilaterally at the level of the posterior superior iliac spine. Four iliac screws were inserted and connected with two rods under the fascia. Percutaneous pedicle screws were inserted at L5 or L4 and connected to the iliac rod using offset connectors. Fracture reduction was then performed.

Results

The average surgical time was 158 min (range, 117–230 min), with an intraoperative bleeding volume of 299 ml (range, 80–480 ml). Thirty-three pedicle screws and 64 iliac screws were implanted with no instance of malpositioning or perforation. A surgical site infection developed in 2 of the 16 cases. Both were deep methicillin-resistant Staphylococcus aureus infections, with the removal of the distal implants required in only one of these cases. Bony union was achieved in all patients, and all vertical displacements reduced by 7.0 mm, on average (range, 5.4–9.0 mm), to < 10 cm. Correction was retained in all cases.

Conclusions

Crab-shaped fixation provides a feasible MIS approach for spinopelvic fixation, which allows good reduction of the vertical displacement of unstable pelvic ring fractures and bony union.

Preventing Fusion Mass Shift Avoids Postoperative Distal Curve Adding-on in Adolescent Idiopathic Scoliosis

BACKGROUND

Surgery for adolescent idiopathic scoliosis (AIS) is only complete after achieving fusion to maintain the correction obtained intraoperatively. The instrumented or fused segments can be referred to as the "fusion mass". In patients with AIS, the ideal fusion mass strategy has been established based on fulcrum-bending radiographs for main thoracic curves. Ideally, the fusion mass should achieve parallel endplates of the upper and lower instrumented vertebra and correct any "shift" for truncal balance. Distal adding-on is an important element to consider in AIS surgery. This phenomenon represents a progressive increase in the number of vertebrae included distally in the primary curvature and it should be avoided as it is associated with unsatisfactory cosmesis and an increased risk of revision surgery. However, it remains unknown whether any fusion mass shift, or shift in the fusion mass or instrumented segments, affects global spinal balance and distal adding-on after curve correction surgery in patients with AIS.

QUESTIONS/PURPOSES

(1) To investigate the relationship among postoperative fusion mass shift, global balance, and distal adding-on phenomenon in patients with AIS; and (2) to identify a cutoff value of fusion mass shift that will lead to distal adding-on.

METHODS

This was a retrospective study of patients with AIS from a single institution. Between 2006 and 2011 we performed 69 selective thoracic fusions for patients with main thoracic AIS. All patients were evaluated preoperatively and at 2 years postoperatively. The Cobb angle between the cranial and caudal endplates of the fusion mass and the coronal shift between them, which was defined as "fusion mass shift", were measured. Patients with a fusion mass Cobb angle greater than 20° were excluded to specifically determine the effect of fusion mass shift on distal adding-on phenomenon. Fusion mass shift was empirically set as 20 mm for analysis. Therefore, of the 69 patients who underwent selective thoracic fusion, only 52 with a fusion mass Cobb angle of 20° or less were recruited for study. We defined patients with a fusion mass shift of 20 mm or less as the balanced group and those with a fusion mass shift greater than 20 mm as the unbalanced group. A receiver operating characteristic (ROC) curve was used to determine the cutoff point of fusion mass shift for adding-on.

RESULTS

Of the 52 patients studied, fusion mass shift (> 20 mm) was noted in 11 (21%), and six of those patients had distal adding-on at final followup. Although global spinal balance did not differ significantly between patients with or without fusion mass shift, the occurrence of adding-on phenomenon was significantly higher in the unbalanced group (55% (six of 11 patients), odds ratio [OR], 8.6; 95% CI, 2-39; p < 0.002) than the balanced group (12% [five of 41 patients]). Based on the ROC curve analysis, a fusion mass shift more than 18 mm was observed as the cutoff point for distal adding-on phenomenon (area under the curve, 0.70; 95% CI, 0.5-0.9; likelihood ratio, 5.0; sensitivity, 0.64; specificity, 0.73; positive predictive value, 39% [seven of 18 patients]; negative predictive value, 88% [30 of 34 patients]; OR, 4.8; 95% CI, 1-20; p = 0.02).

CONCLUSIONS

Our study illustrates the substantial utility of the fulcrum-bending radiograph in determining fusion levels that can avoid fusion mass shift; thereby, underlining its importance in designing personalized surgical strategies for patients with scoliosis. Preoperatively, determining fusion levels by fulcrum-bending radiographs to avoid residual fusion mass shift is imperative. Intraoperatively, any fusion mass shift should be corrected to avoid distal adding-on, reoperation, and elevated healthcare costs.

LEVEL OF EVIDENCE

Level II, prognostic study.

Regional tissue oxygen saturation measured by near-infrared spectroscopy to assess the depth of burn injuries

The burn severity depends on the wound depth and area affected. Hitherto burn depth has been judged mainly by visual observation, although concerns have been raised about its validity. The regional tissue blood flow (rTBF) measured by laser Doppler imaging (LDI) in damaged tissue correlates with the depth. However, very few reports are available on the significance of the regional tissue oxygen saturation (rSO2) as an indicator of burn depth. We investigated whether rSO2 by Near-infrared spectroscopy (NIRS) in burn injuries correlates with rTBF by LDI, which would facilitate quantification of the severity of the tissue damage.

METHODS

We measured rTBF and rSO2 in 50 lesions from 14 patients of burn injury within 24 hours after injury. The correlation between rTBF and rSO2 was evaluated by Spearman rank correlation analysis.

RESULTS

The rSO2 (%; range, 52-82) by NIRS and the rTBF (perfusion unit; range, 61-704) by LDI in burn lesions were positively correlated (r=0.755, p<0.001). This statistically positive correlation still remained significant (r=0.678, p<0.001) after the rSO2 values were standardized.

CONCLUSION

This study suggests that NIRS determination of rSO2 in burn injuries shows promise as a reliable and quick method to estimate the depth of burn lesion.

Degenerative spondylolisthesis does not influence surgical results of laminoplasty in elderly cervical spondylotic myelopathy patients

The objective of the study was to investigate the comorbidity of degenerative spondylolisthesis (DS), in elderly cervical spondylotic myelopathy (CSM) patients in our hospital, and the correlation between surgical results and preoperative DS. There are few studies on the outcome of laminoplasty for CSM with DS. A total of 49 elderly patients (>65 years old) who eventually had surgical treatment for CSM were evaluated. A slippage displacement of more than 2.5 mm at least at one level was classified to have a positive DS on flexion/extension radiographs (DS group). A slippage displacement less than 1.0 mm was considered a negative DS (non-DS group). Seventeen patients who had slippage of 1.0-2.5 mm were excluded from the study. The DS group (n = 15) included cases with DS at preoperation, while the remaining cases (n = 17) belonged to the non-DS group. The flexion/extension radiographs of the two groups were compared for range of motion and clinical results at 3 years after the operation. Of all elderly patients, 30.6% had DS. There was no significant difference between the two groups based on the clinical results. The range of motion of all cervical spines (DS group and non-DS group) was significantly limited. However, there was no significant difference between the two groups. New postoperative DS appeared in four patients, of which two were from the DS group and two from the non-DS group. These data suggest that degenerative spondylolisthesis does not influence surgical results in elderly cervical spondylotic myelopathy patients.

Temporal changes in the tensile strength of ultra-high-molecular-weight polyethylene cable embedded in muscle tissue

BACKGROUND

Wires and cables have been used extensively for spinal sublaminar wiring, but damages to the spinal cord due to compression by metal wires have been reported. We have used more flexible ultra-high-molecular-weight polyethylene cable (Tekmilon tape) instead of metal wires since 1999 and have obtained good clinical outcomes. Although the initial strength of Tekmilon tape is equivalent to metal wires, the temporal changes in the strength of Tekmilon tape in the body should be investigated to show that sufficient strength is maintained over time until bone union is complete.

METHODS

Tekmilon tape was embedded into the paravertebral muscle of 10-week-old male Japanese white rabbits. Samples were embedded for 0, 1, 3, 6 or 12 months. At the end of each period, sequential straight tensile strength and sequential knot-pull tensile strength were measured.

FINDINGS

The initial strength of Tekmilon tape in muscle tissue was maintained over time, with 92% straight tensile strength and 104% knot-pull tensile strength at 6months, and values of 77% and 100% at 12 months, respectively. Since single knot is clinically relevant, it is very important that the knot-pull tensile strength did not decrease over a 12-month period. This suggests that temporal changes in the tensile strength of Tekmilon tape are negligible at 1 year.

INTERPRETATION

Tekmilon tape maintains sufficient strength in vivo until bone union has occurred. It is useful for sublaminar wiring instead of metal materials due to its flexibility and strength and may reduce the risk of neurological damage.

Raloxifene: its ossification-promoting effect on female mesenchymal stem cells

BACKGROUND

Raloxifene acts like estrogen in preventing bone loss in postmenopausal women, but it selectively activates biological responses in bone tissue. It has a direct effect on osteoblasts' differentiation and bone formation in bone marrow culture. However, the point at which raloxifene has an effect on bone marrow-derived mesenchymal stem cells (MSCs), regardless of sex difference, is not known. The purpose of this study was to examine the osteogenic effect of raloxifene on MSCs derived from female and male rats and to assess the sex difference of raloxifene with or without osteogenic supplements (OSs) in the regulation of bone formation.

METHODS

Female and male rat bone marrow cells were cultured with or without OSs. In each experimental group, 10-6 M or 10-8 M raloxifene was added. As a control, cells were cultured without raloxifene. Histologically, mineralization was assessed by alizarin red S staining. Biochemically, alkaline phosphatase (ALP) activity, calcium content, and osteocalcin content were assessed.

RESULTS

On histological analysis, mineralized nodules were seen on alizarin red S staining in the groups treated with OS. On the biochemical analysis, OS increased ALP activity, calcium content, and osteocalcin content. Among female groups with OSs, 10-6 M raloxifene significantly increased ALP activity, calcium content, and osteocalcin content compared with the controls. Among male groups, raloxifene had negligible effects.

CONCLUSIONS

10-6 M Raloxifene had no ossification-inducing effect on female MSCs, but it had an ossification-promoting effect; it had no osteogenic effect on male MSCs. Therefore, raloxifene has a sex difference with regard to its osteogenic effect on MSCs. Moreover, combined treatment with raloxifene plus OS has an effect on female MSCs. These results provide a useful insight into the possible influence of raloxifene after MSC transplantation in clinical practice.

Does developmental canal stenosis influence surgical results of bilateral open-door laminoplasty for cervical spondylotic myelopathy?

OBJECT

The purpose of this study was to investigate the prevalence of developmental canal stenosis in patients with cervical spondylotic myelopathy (CSM), and the correlation between surgical results and degree of developmental canal stenosis.

METHODS

A total of 112 patients who eventually had surgical treatment for CSM were evaluated. Male patients whose sagittal spinal diameter was < 14 mm and females whose sagittal diameter was < 13 mm even at one level were classified as having developmental canal stenosis. Two groups of patients were used in this study; the "positive" group (57 cases) included patients with developmental canal stenosis preoperatively, whereas the "negative" group (55 cases) excluded such patients. Lateral functional radiographs obtained in patients in the 2 groups were compared for range of motion and clinical results.

RESULTS

Developmental canal stenosis was found in 50.9% of all cases. Based on clinical results, there was no significant difference between the 2 groups.

CONCLUSIONS

Patients with CSM showed a high incidence of preoperative developmental canal stenosis. However, there were no significant differences in clinical results between patients with and without this disorder. These results indicate that developmental canal stenosis is not a factor that influences surgical results.

Spectrocolorimetric evaluation of repaired articular cartilage after a microfracture

Background

In clinical practice, surgeons differentiate color changes in repaired cartilage compared with surrounding intact cartilage, but cannot quantify these color changes. Objective assessments are required. A spectrocolorimeter was used to evaluate whether intact and repaired cartilage can be quantified.

Findings

We investigated the use of a spectrocolorimeter and the application of two color models (L* a* b* colorimetric system and spectral reflectance distribution) to describe and quantify articular cartilage. In this study, we measured the colors of intact and repaired cartilage after a microfracture. Histologically, the repaired cartilage was a mixture of fibrocartilage and hyaline cartilage. In the L* a* b* colorimetric system, the L* and a* values recovered to close to the values of intact cartilage, whereas the b* value decreased over time after the operation. Regarding the spectral reflectance distribution at 12 weeks after the operation, the repaired cartilage had a higher spectral reflectance ratio than intact cartilage between wavelengths of 400 to 470 nm.

Conclusion

This study reports the first results regarding the relationship between spectrocolorimetric evaluation and the histological findings of repair cartilage after a microfracture. Our findings demonstrate the ability of spectrocolorimetric measurement to judge the repair cartilage after treatment on the basis of objective data such as the L*, a* and b* values and the SRP as a coincidence index of the spectral reflectance curve.

[A case of two primary carcinomas: thyroid papillary carcinoma with anaplastic transformation of metastatic cervical lymph node and breast cancer]

Reported is the case of a 70-year-old woman who, on diagnosis, was found to have a papillary carcinoma of the thyroid gland that showed an anaplastic transformation of a metastatic lesion of the right cervical lymph node. The primary lesion, however, contained no anaplastic areas. Simultaneously, she also was found to have a primary carcinoma of the left breast, an invasive ductal carcinoma. She thus received a total thyroidectomy with a right cervical node dissection, a modified radical mastectomy, and irradiation of the right cervical area, but no intensive chemotherapy was performed. Six months after the thyroidectomy, the anaplastic carcinoma caused her death. On autopsy, it was found to have involved the right cervical area, the lungs, the mediastinum, the right axilla, and the right kidney.

A light and electron microscopic study of the regenerative epithelium in the intrahepatic bile duct. Experimental study of local direct instillation of paraquat into the intrahepatic bile ducts of rats

To date, no reliable report on the regeneration of the intrahepatic bile duct epithelium following damage to the duct has been published. In this study, a direct instillation of paraquat dichloride into the intrahepatic bile ducts of rats was carried out, and the livers were examined under light and electron microscopy. One hour after treatment, the biliary epithelia showed degeneration and necrosis, and these changes remained for a considerable period in a large majority of the ducts examined. Three weeks after instillation, low columnar epithelium consisting of hyperchromatic nuclei and eosinophilic cytoplasm was present in a medium-sized bile duct, which was collared by marked periductal fibrosis. Electron microscopically, the eosinophilic epithelium showed a marked increase in the number of rough endoplasmic reticula, ribosomes, mitochondria, and filamentous structures, suggesting an active viability of the cell. Subsequently, the eosinophilic cells were replaced by normal-appearing epithelium, not associated with the periductal fibrosis. The data suggest that an epithelial regeneration occurred in the intrahepatic duct following injury and that this activity may be similar to that of the extrahepatic bile duct epithelium.

Acute toxic effects of paraquat on ultrastructure of rat liver

Paraquat was administrated to pathogen-free male rats orally, and the livers were studied by light and electron microscope at intervals of 6 hours to 5 days. Congestion and hepatocellular injury (degeneration and/or fatty metamorphosis) were seen by light microscope. Electron microscope showed that degranulation of RER, proliferation of SER, decreasing of glycogen particles and mitochondrial swelling occurred in the cytoplasm of the hepatocytes within 2 layers around the central vein at 6 hours. After 12 hours the liver cells throughout the centrolobular area were injured. Degranulation of RER, proliferation of SER, and decreasing of glycogen particles became prominent, and mitochondria showed swelling and transformation. In the midzonal and periportal areas, numerous lipid droplets were seen in the cytoplasm of the hepatocytes. From the result of ultrastructural findings, it is considered that detoxication and biotransformation of paraquat occur in the hepatocytes within 2 layers around the central vein at an early stage, and spread to the hepatocytes throughout centrolobular area later.

A histopathological study of the liver in paraquat poisoning--an analysis of fourteen autopsy cases with emphasis on bile duct injury

Fourteen autopsy cases of paraquat poisoning were studied. Seven of the eight patients who died within 4 days after the ingestion of paraquat showed hepatocytic injury, and three of them revealed bile duct injury. Hepatocytic injury was similar to that of carbon tetrachloride intoxication. Bile duct injury consisted of epithelial changes of the bile ductules and bile ducts. Cholestasis in the bile ducts was produced by the injury. The affected bile ductules and ducts had hydropic and necrotic epithelium, associated with the infiltration of neutrophils and histiocytes in the intraductal and periductal tissues. The severity of bile duct injury increased gradually from the bile ductules to the septal bile ducts. The extrahepatic biliary tract showed the same injury as the septal bile ducts in one case. It is considered that bile duct injury was produced by a direct corrosive effect of paraquat. Five of the six patients who survived more than 8 days revealed intrahepatic cholestasis, the pathogenesis of which was not clearly understood.

Infantile GM1-gangliosidosis with marked manifestation of lungs

GM1-gangliosidosis is a disease characterized by abnormal accumulation of GM1-ganglioside in the brain and viscera. The disease is characterized by clinical findings similar to Hurler's disease and pathologic features resembling Niemann-Pick's disease but with involvement of the glomerular epithelium. A 14-month-old boy, clinically diagnosed as GM1-gangliosidosis, died of respiratory insufficiency and was autopsied except for the brain. Biochemically, marked increase of GM1-ganglioside in the viscera was demonstrated. Pathologically, the foam cells were present in the viscera. Some parts of the cytoplasmic vacuoles in the lungs and spleen contained osmiophilic fibrillar material electron-microscopically. This case was characterized by marked accumulation of foam cells in the pulmonary alveolar spaces.