Self-organization, quality control, and preclinical studies of human iPSC-derived retinal sheets for tissue-transplantation therapy

Three-dimensional retinal organoids (3D-retinas) are a promising graft source for transplantation therapy. We previously developed self-organizing culture for 3D-retina generation from human pluripotent stem cells (hPSCs). Here we present a quality control method and preclinical studies for tissue-sheet transplantation. Self-organizing hPSCs differentiated into both retinal and off-target tissues. Gene expression analyses identified the major off-target tissues as eye-related, cortex-like, and spinal cord-like tissues. For quality control, we developed a qPCR-based test in which each hPSC-derived neuroepithelium was dissected into two tissue-sheets: inner-central sheet for transplantation and outer-peripheral sheet for qPCR to ensure retinal tissue selection. During qPCR, tissue-sheets were stored for 3-4 days using a newly developed preservation method. In a rat tumorigenicity study, no transplant-related adverse events were observed. In retinal degeneration model rats, retinal transplants differentiated into mature photoreceptors and exhibited light responses in electrophysiology assays. These results demonstrate our rationale toward self-organizing retinal sheet transplantation therapy.

Competency of iPSC-derived retinas in MHC-mismatched transplantation in non-human primates

Transplantation of embryonic/induced pluripotent stem cell-derived retina (ESC/iPSC-retina) restores host retinal ganglion cell light responses in end-stage retinal degeneration models with host-graft synapse formation. We studied the immunological features of iPSC-retina transplantation using major histocompatibility complex (MHC)-homozygote monkey iPSC-retinas in monkeys with laser-induced retinal degeneration in MHC-matched and -mismatched transplantation. MHC-mismatched transplantation without immune suppression showed no evident clinical signs of rejection and histologically showed graft maturation without lymphocytic infiltration, although immunological tests using peripheral blood monocytes suggested subclinical rejection in three of four MHC-mismatched monkeys. Although extensive photoreceptor rosette formation was observed on histology, evaluation of functional integration using mouse models such as mouse ESC-retina (C57BL/6) transplanted into rd1(C3H/HeJ, MHC-mismatched model) elicited light responses in the host retinal ganglion cells after transplantation but with less responsiveness than that in rd1-2J mice (C57BL/6, MHC-matched model). These results suggest the reasonable use of ESC/iPSC-retina in MHC-mismatched transplantation, albeit with caution.

A Genetic modification that reduces ON-bipolar cells in hESC-derived retinas enhances functional integration after transplantation

Pluripotent stem cell (PSC)-derived retinal sheet transplanted in vivo can form structured photoreceptor layers, contact with host bipolar cells, and transmit light signals to host retinas. However, a major concern is the presence of graft bipolar cells that may impede host-graft interaction. In this study, we used human ESC-retinas with the deletion of Islet-1 (ISL1) gene to achieve the reduced graft ON-bipolar cells after xenotransplantation into end-stage retinal degeneration model rats. Compared with wild-type graft, ISL1^−/− hESC-retinas showed better host-graft contact, with indication of host-graft synapse formation and significant restoration of light responsiveness in host ganglion cells. We further analyzed to find out that improved functional integration of ISL1^−/− hESC-retinas seemed attributed by a better host-graft contact and a better preservation of host inner retina. ISL1^−/− hESC-retinas are promising for the efficient reconstruction of a degenerated retinal network in future clinical application.

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Deletion of ISL1 in hESC-retinas resulted in a reduced number of ON-bipolar cells

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Photoreceptors in ISL1^−/− hESC-retinas achieved functional maturation in vivo

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ISL1^−/− hESC-retinas showed better host-graft contact with putative synapses

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ISL1^−/− hESC-retinas better restored RGC light responsiveness in degenerated retina

Genetically engineered stem cell-derived retinal grafts for improved retinal reconstruction after transplantation

ESC/iPSC-retinal sheet transplantation, which supplies photoreceptors as well as other retinal cells, has been shown to be able to restore visual function in mice with end-stage retinal degeneration. Here, by introducing a novel type of genetically engineered mouse ESC/iPSC-retinal sheet with reduced numbers of secondary retinal neurons but intact photoreceptor cell layer structure, we reinforced the evidence that ESC/iPSC-retinal sheet transplantation can establish synaptic connections with the host, restore light responsiveness, and reduce aberrant retinal ganglion cell spiking in mice. Furthermore, we show that genetically engineered grafts can substantially improve the outcome of the treatment by improving neural integration. We speculate that this leads to reduced spontaneous activity in the host which in turn contributes to a better visual recovery.

Multielectrode Array Recording of Mouse Retinas Transplanted with Stem Cell-Derived Retinal Sheets

Retinal multielectrode array (MEA) recording allows us to examine the action potentials of retinal ganglion cells and field potentials of photoreceptors and bipolar cells. In addition to studying the retinal circuitry, it has become one of the standard examination tools for the characterization of stem cell-derived retinal transplantation in degenerated retinas. Besides the detection of responses to simple light stimulation, it is also necessary to consider the spatial correlation of the graft and the electrodes, in order to unbiasedly reveal the locally reconstructed retinal circuitry after transplantation. Here, we introduce our newly developed protocol of MEA recording and analysis that may serve as a standard for evaluating transplanted retinas.

Unique genetic profiles from cerebrospinal fluid cell-free DNA in leptomeningeal metastases of EGFR-mutant non-small-cell lung cancer: a new medium of liquid biopsy

Background

Leptomeningeal metastases (LM) are more frequent in non-small-cell lung cancer (NSCLC) with epidermal growth factor receptor (EGFR) mutations. Due to limited access to leptomeningeal lesions, the purpose of this study was to explore the potential role of cerebrospinal fluid (CSF) as a source of liquid biopsy in patients with LM.

Patients and methods

Primary tumor, CSF, and plasma in NSCLC with LM were tested by next-generation sequencing. In total, 45 patients with suspected LM underwent lumbar puncture, and those with EGFR mutations diagnosed with LM were enrolled.

Results

A total of 28 patients were enrolled in this cohort; CSF and plasma were available in 26 patients, respectively. Driver genes were detected in 100% (26/26), 84.6% (22/26), and 73.1% (19/26) of samples comprising CSF cell-free DNA (cfDNA), CSF precipitates, and plasma, respectively; 92.3% (24/26) of patients had much higher allele fractions in CSF cfDNA than the other two media. Unique genetic profiles were captured in CSF cfDNA compared with those in plasma and primary tissue. Multiple copy number variations (CNVs) were mainly identified in CSF cfDNA, and MET copy number gain identified in 47.8% (11/23) of patients was the most frequent one, while other CNVs included ERBB2, KRAS, ALK, and MYC. Moreover, loss of heterozygosity (LOH) of TP53 was identified in 73.1% (19/26) CSF cfDNA, which was much higher than that in plasma (2/26, 7.7%; P < 0.001). There was a trend towards a higher frequency of concomitant resistance mutations in patients with TP53 LOH than those without (70.6% versus 33.3%; P = 0.162). EGFR T790M was identified in CSF cfDNA of 30.4% (7/23) of patients who experienced TKI progression.

Conclusion

CSF cfDNA could reveal the unique genetic profiles of LM and should be considered as the most representative liquid biopsy medium for LM in EGFR-mutant NSCLC.

Quantitative and Qualitative Evaluation of Photoreceptor Synapses in Developing, Degenerating and Regenerating Retinas

Quantitative and qualitative evaluation of synapses is crucial to understand neural connectivity. This is particularly relevant now, in view of the recent advances in regenerative biology and medicine. There is an urgent need to evaluate synapses to access the extent and functionality of reconstructed neural network. Most of the currently used synapse evaluation methods provide only all-or-none assessments. However, very often synapses appear in a wide spectrum of transient states such as during synaptogenesis or neural degeneration. Robust evaluation of synapse quantity and quality is therefore highly sought after. In this paper we introduce QUANTOS, a new method that can evaluate the number, likelihood, and maturity of photoreceptor ribbon synapses based on graphical properties of immunohistochemistry images. QUANTOS is composed of ImageJ Fiji macros, and R scripts which are both open-source and free software. We used QUANTOS to evaluate synaptogenesis in developing and degenerating retinas, as well as de novo synaptogenesis of mouse iPSC-retinas after transplantation to a retinal degeneration mouse model. Our analysis shows that while mouse iPSC-retinas are largely incapable of forming synapses in vitro, they can form extensive synapses following transplantation. The de novo synapses detected after transplantation seem to be in an intermediate state between mature and immature compared to wildtype retina. Furthermore, using QUANTOS we tested whether environmental light can affect photoreceptor synaptogenesis. We found that the onset of synaptogenesis was earlier under cyclic light (LD) condition when compared to constant dark (DD), resulting in more synapses at earlier developmental stages. The effect of light was also supported by micro electroretinography showing larger responses under LD condition. The number of synapses was also increased after transplantation of mouse iPSC-retinas to rd1 mice under LD condition. Our new probabilistic assessment of synapses may prove to be a valuable tool to gain critical insights into neural-network reconstruction and help develop treatments for neurodegenerative disorders.

Medium- to long-term survival and functional examination of human iPSC-derived retinas in rat and primate models of retinal degeneration

Background

We have previously reported that xeno-transplanted human ESC-derived retinas are able to mature in the immunodeficient retinal degeneration rodent models, similar to allo-transplantations using mouse iPSC-derived retina. The photoreceptors in the latter developed outer segments and formed synapses with host bipolar cells, driving light responses of host retinal ganglion cells. In view of clinical application, here we further confirmed the competency of human iPSC-derived retina (hiPSC-retina) to mature in the degenerated retinas of rat and monkey models.

Methods

Human iPSC-retinas were transplanted in rhodopsin mutant SD-Foxn1 Tg(S334ter)3LavRrrc nude rats and two monkeys with laser-induced photoreceptor degeneration. Graft maturation was studied by immunohistochemistry and its function was examined by multi-electrode array (MEA) recording in rat retinas and visually-guided saccade (VGS) in a monkey.

Findings

A substantial amount of mature photoreceptors in hiPSC-retina graft survived well in the host retinas for at least 5 months (rat) to over 2 years (monkey). In 4 of 7 transplanted rat retinas, RGC light responses were detected at the grafted area. A mild recovery of light perception was also suggested by the VGS performance 1.5 years after transplantation in that monkey.

Interpretation

Our results support the competency of hiPSC-derived retinas to be clinically applied for transplantation therapy in retinal degeneration, although the light responses observed in the present models were not conclusively distinguishable from residual functions of degenerating host retinas. The functional analysis may be further elaborated using other models with more advanced retinal degeneration.

Culture Systems of Dissociated Mouse and Human Pluripotent Stem Cell-Derived Retinal Ganglion Cells Purified by Two-Step Immunopanning

Purpose

We aimed to establish purification and culture systems for retinal ganglion cells (RGCs) differentiated from mouse and human pluripotent stem cells (PSC) for in vitro and regenerative medicine studies.

Methods

We used a two-step immunopanning method to purify RGCs from mouse and human PSC-derived three-dimensional (3D) retinal organoids. To assess the method, we purified RGCs from 3D retinal organoids derived from embryonic stem cells (ESCs) generated from Thy1-EGFP transgenic (TG) mice. In addition, 3D retinal organoids differentiated from human induced PSCs (iPSCs) were cultured for up to differentiation day (DD) 120, and RGCs were purified by immunopanning. RGC marker expressions were confirmed by immunostaining and reverse transcription-quantitative PCR. The purified RGCs were cultured, and neurite outgrowth was measured and analyzed using an IncuCyte Zoom system.

Results

Mouse RGCs purified from Thy1-EGFP TG mouse retinas and the ESC-derived 3D retinas could be maintained for approximately 2 to 3 weeks, expressing the markers BRN3B and SMI-312. Purified RGCs from human iPSC-derived retinal organoids expressed RGC markers and could be maintained for up to 4 weeks. The RGCs collected at DD 90 to 110 extended longer neurites than those collected at younger stages.

Conclusions

We successfully purified RGCs from mouse and human PSC-derived 3D retinal organoids cultured for approximately 120 days. RGCs from older retinal organoids would be useful for neurite tracking. This method would be effective not only for studying the pathology of human RGC diseases but also for therapeutic drug studies and RGC transplantation.

Establishment of Immunodeficient Retinal Degeneration Model Mice and Functional Maturation of Human ESC-Derived Retinal Sheets after Transplantation

Increasing demand for clinical retinal degeneration therapies featuring human ESC/iPSC-derived retinal tissue and cells warrants proof-of-concept studies. Here, we established two mouse models of end-stage retinal degeneration with immunodeficiency, NOG-rd1-2J and NOG-rd10, and characterized disease progress and immunodeficient status. We also transplanted human ESC-derived retinal sheets into NOG-rd1-2J and confirmed their long-term survival and maturation of the structured graft photoreceptor layer, without rejection or tumorigenesis. We recorded light responses from the host ganglion cells using a multi-electrode array system; this result was consistent with whole-mount immunostaining suggestive of host-graft synapse formation at the responding sites. This study demonstrates an application of our mouse models and provides a proof of concept for the clinical use of human ESC-derived retinal sheets.

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Two mouse models of immunodeficient end-stage retinal degeneration were established

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Immunodeficient host permitted transplantation of human ESC-derived retinal sheets

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Transplanted human ESC-derived retinal sheets survived long term and maturated

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After transplantation, light responses were recorded from the degenerated host retina

A phase III randomised controlled trial of erlotinib vs gefitinib in advanced non-small cell lung cancer with EGFR mutations

Background:

A phase III trial was conducted to compare the safety and efficacy of erlotinib with that of gefitinib in advanced non-small cell lung cancer harbouring epidermal growth factor receptor mutations in exon 19 or 21.

Methods:

Eligible patients were randomised to receive erlotinib (150 mg per day) or gefitinib (250 mg per day) orally until disease progression or unacceptable toxicity. We aimed to determine whether erlotinib is superior to gefitinib in efficacy. The primary end point was progression-free survival.

Results:

A total of 256 patients were randomised to receive erlotinib (N=128) or gefitinib (N=128). Median progression-free survival was not better with erlotinib than with gefitinib (13.0 vs 10.4 months, 95% confidence interval (CI) 0.62–1.05, P=0.108). The corresponding response rates and median overall survival were 56.3% vs 52.3% (P=0.530) and 22.9 vs 20.1 months (95% CI 0.63–1.13, P=0.250), respectively. There were no significant differences in grade 3/4 toxicities between the two arms (P=0.172).

Conclusions:

The primary end point was not met. Erlotinib was not significantly superior to gefitinib in terms of efficacy in advanced non-small cell lung cancer with epidermal growth factor receptor mutations in exon 19 or 21, and the two treatments had similar toxicities.

Patch Clamp Recording of Starburst Amacrine Cells in a Flat-mount Preparation of Deafferentated Mouse Retina

The mammalian retina is a layered tissue composed of multiple neuronal types. To understand how visual signals are processed within its intricate synaptic network, electrophysiological recordings are frequently used to study connections among individual neurons. We have optimized a flat-mount preparation for patch clamp recording of genetically marked neurons in both GCL (ganglion cell layer) and INL (inner nuclear layer) of mouse retinas. Recording INL neurons in flat-mounts is favored over slices because both vertical and lateral connections are preserved in the former configuration, allowing retinal circuits with large lateral components to be studied. We have used this procedure to compare responses of mirror-partnered neurons in retinas such as the cholinergic starburst amacrine cells (SACs).

Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina

Gap junctions are composed of connexin 36 (Cx36) and play a critical role in the rod photoreceptor signaling pathways of the vertebrate retina. Despite the fact that their connection and modulation in various rod pathways have been extensively studied in adult animals, little is known about the contribution and regulation of gap junctions to the development of the AII amacrine cell (AC)-mediated rod pathway. Using immunohistochemistry and microinjection, this study demonstrates a steady increase in relative Cx36 protein expression in both plexiform layers of the rabbit retina at around the time of eye opening. However, immediately after eye opening, most Cx36 immunoreactive AII ACs show no gap junction coupling pattern to neighboring cells and it is not until the third postnatal week that AII cells begin to exhibit an adult-like tracer-coupling pattern. Moreover, studies using dark-rearing and AMPA receptor blockade during postnatal development both revealed that relative levels of Cx36 immunoreactivity in AII ACs were increased when neural activity was inhibited. Our findings suggest that Cx36 expression in the AII-mediated rod pathway is activity dependent in the developing rabbit retina.

A Novel Retinal Oscillation Mechanism in an Autosomal Dominant Photoreceptor Degeneration Mouse Model

It has been shown in rd1 and rd10 models of photoreceptor degeneration (PD) that inner retinal neurons display spontaneous and rhythmic activities. Furthermore, the rhythmic activity has been shown to require the gap junction protein connexin 36, which is likely located in AII amacrine cells (AII-ACs). In the present study, an autosomal dominant PD model called rhoΔCTA, whose rods overexpress a C-terminally truncated mutant rhodopsin and degenerate with a rate similar to that of rd1, was used to investigate the generality and mechanisms of heightened inner retinal activity following PD. To fluorescently identify cholinergic starburst amacrine cells (SACs), the rhoΔCTA mouse was introduced into a combined ChAT-IRES-Cre and Ai9 background. In this mouse, we observed excitatory postsynaptic current (EPSC) oscillation and non-rhythmic inhibitory postsynaptic current (IPSC) in both ON- and OFF-SACs. The IPSCs were more noticeable in OFF- than in ON-SACs. Similar to reported retinal ganglion cell (RGC) oscillation in rd1 mice, EPSC oscillation was synaptically driven by glutamate and sensitive to blockade of NaV channels and gap junctions. These data suggest that akin to rd1 mice, AII-AC is a prominent oscillator in rhoΔCTA mice. Surprisingly, OFF-SAC but not ON-SAC EPSC oscillation could readily be enhanced by GABAergic blockade. More importantly, weakening the AII-AC gap junction network by activating retinal dopamine receptors abolished oscillations in ON-SACs but not in OFF-SACs. Furthermore, the latter persisted in the presence of flupirtine, an M-type potassium channel activator recently reported to dampen intrinsic AII-AC bursting. These data suggest the existence of a novel oscillation mechanism in mice with PD.

Vertebral bone marrow perfusion evaluated with dynamic contrast-enhanced MR imaging: significance of aging and sex

PURPOSE

To investigate blood perfusion of nonfractured, normal-appearing vertebral bodies with regard to age and sex.

MATERIALS AND METHODS

Dynamic magnetic resonance imaging (160 images obtained in 80 seconds) was performed from T10 to L5 in 66 patients. Patients were assigned to three groups: group 1, those 50 years or younger without compression fracture; group 2, those older than 50 years without compression fracture; or group 3, those older than 50 years with compression fracture. Peak enhancement percentage and enhancement slope were determined from the time-intensity curve of normal (nonfractured) vertebral body. Comparisons were made between groups, and the effect of age and sex interaction was analyzed.

RESULTS

Higher peak enhancement percentage was demonstrated for group 1 compared with group 2 (58.21 +/- 44.65 [SD] vs 21.88 +/- 14.77, P <.005). Group 1 women revealed a higher enhancement percentage compared with group 1 men (87.17 +/- 54.13 vs 38.16 +/- 21.69, P <.05), which significantly decreased in those older than 50 years (from 87.17 +/- 54.13 to 17.98 +/- 13.80, P <.005). For men, this decrease in those older than 50 years was not as pronounced (from 38.16 +/- 21.69 to 25.38 +/- 15.43, P >.05). Presence of compression fracture at other levels of the spine (group 3) was not associated with a different enhancement percentage for normal vertebrae.

CONCLUSION

Rate of vertebral bone marrow perfusion revealed a significant decrease in subjects older than 50 years. Women demonstrated a higher marrow perfusion rate than men younger than 50 years and a more marked decrease than men older than 50 years.

Effect of theophylline on airway inflammation in asthma

AIM

To investigate whether low dose theophylline has an anti-inflammatory effect in asthma.

METHODS

Nineteen asthmatic subjects were given 200 mg sustained-release theophylline preparation twice daily for 4 weeks. The mean serum concentration of theophylline was 7.9 mg/L. The percentage of eosinophils, EG2+ eosinophils, and the level of eosinophil cationic protein (ECP) in sputum pre- and post-administration were detected by Wright's stain, immunocytochemistry, and immuno-CAP system, and the symptom scores and lung function were evaluated as well. The above indices for 10 healthy subjects were regarded as control.

RESULTS

Before using theophylline, sputum eosinophils, EG2+ eosinophils, and ECP in asthmatic group were much higher than those of healthy group. After four weeks administration, there were great decreases in percentage of total eosinophils (40 % +/- 17 % vs 29 % +/- 11 %, P < 0.01), activated (EG2+) eosinophils (28 % +/- 9 % vs 10 % +/- 8 %, P < 0.01) and in the concentration of sputum ECP [(373 +/- 206) vs (220 +/- 132) microg/L, P < 0.01]. The symptom scores decreased greatly (7.1 +/- 1.2 vs 5.4 +/- 1.6, P < 0.01). There was a marked increased in forced expiratory volume one second (FEV(1.0)) after administration (2.2 +/- 0.6 vs 2.4 +/- 0.5, P < 0.01). The FEV(1.0) % of asthmatic subjects after administration increased (60 % +/- 13 % vs 65 % +/- 13 %, P < 0.01), too.

CONCLUSION

These results indicated that low dose theophylline had inhibitory action on airway inflammation in asthma with noticeable improvement of the patients' symptoms and lung function.

Paget's disease of the bone: a case report

Paget's disease of bone is rare in Asia. We report a case of Paget's disease in a 58-year-old Taiwanese man who was admitted with a 3-month history of bilateral numbness in the buttock region. Laboratory data disclosed an elevated serum alkaline phosphatase level (510 U/L). Plain radiographs of the lumbar spine showed generalized increased density at the third lumbar vertebra, associated with cortical thickening, loss of cortico-cancellous definition, and increased anteroposterior diameter. The T1-weighted magnetic resonance image of the lumbar spine showed diffuse, heterogeneous low signal intensity at the third lumbar vertebral body, pedicle, laminae, and spinal process; these areas showed mixed high and low signal intensity on the T2-weighted image. Technetium-99m bone scan revealed abnormal uptake in the involved vertebra. Histologic examination of the third lumbar spinal process confirmed the diagnosis of Paget's disease of bone. The patient remained well during a follow-up period of 6 months.

Carbon dioxide enhanced ultrasonography of hepatic haemangiomas

The purpose of this study was to characterize the imaging manifestations of carbon dioxide enhanced ultrasonography (CO2US) in hepatic haemangiomas. CO2US was performed for 52 haemangiomas in 25 patients and for 352 various hepatic nodules in 192 patients. Characteristic enhancement patterns for hepatic haemangiomas were noted. All 39 large haemangiomas (> 1 cm) demonstrated peripheral nodular enhancement in the early and parenchymal phases associated with delayed washout character (> 30 min). Centripetal fill-in of CO2 was noted in 82.1% of large haemangiomas. Two enhancing patterns were noted in 13 small haemangiomas (< 1 cm): peripheral nodular (69.2%) and homogeneous (30.8%). Delayed washout was also noted in all small haemangiomas. Centripetal fill-in of CO2 was hard to define in small haemangiomas. None of the other 352 hepatic nodules had the same imaging features. In conclusion we found that CO2US is valuable in differentiating hepatic haemangiomas from other liver tumours in clinically doubtful cases.

Intra-arterial carbon dioxide-enhanced ultrasonogram of hepatocellular carcinoma treated by transcatheter arterial embolization and percutaneous ethanol injection therapy

The purpose of this study was to investigate the value of carbon dioxide-enhanced ultrasonography (CO2-US) in the evaluation of viable hepatocellular carcinomas (HCC) which were treated by transcatheter arterial embolization (TAE), percutaneous ethanol injection (PEI), or a combination treatment (TAE and PEI). Forty-one patients with 66 HCC were included in the study. They underwent CO2-US and angiography were performed in all tumours after they were treated by TAE, PEI or a combination treatment. Forty-six tumours were positively enhanced by CO2-US and 40 of them were positive by angiography. These 46 tumours were proved to be viable tumours either by biopsy or by follow-up studies. The positive predictive value was 100% for CO2-US and 87.8% in angiography. Twenty tumours were negative by CO2-US and these were also negative by angiography. Carbon dioxide-enhanced ultrasonography is a more reliable method for detecting the viable portion of the treated HCC compared with conventional angiography.

Laryngeal tuberculosis: a series of 46 patients

BACKGROUND

The incidence of laryngeal tuberculosis is declining after the advent of anti-tuberculous drugs. The disease itself is changing according to our experience, too. The changing pattern is our interest.

METHODS

A series of 46 cases of laryngeal tuberculosis seen in our institution between 1980 and 1995 were reviewed retrospectively to assess the various features of the disease.

RESULTS

The results showed a mean age of 48 years and a sex ratio of 2:1. Hoarseness is the most frequent presenting symptom (80%), and sore throat (52%) is another important symptom. The frequent locations of lesions are the true cords (57%), epiglottis (39%), false cords (35%), arytenoids (24%) and posterior commissure (7%). Laryngeal tuberculosis was the most common initial working diagnosis before a definite pathological report was completed. In 85% of the patients the disease was transmitted by bronchogenic route, and in the others it was primary laryngeal tuberculosis. Laryngeal tuberculosis responds well to early treatment with anti-tuberculous chemotherapy.

CONCLUSION

The clinical presentation of laryngeal tuberculosis is changing. It is necessary to detect the disease early to prevent the development of severe sequalae or mortality.

The value of ultrasound measurement of gallbladder wall thickness in predicting laparoscopic operability prior to cholecystectomy

We prospectively analysed 51 consecutive cases who underwent laparoscopic cholecystectomy from June 1992 to February 1993. There were 35 cases of chronic cholecystitis and 16 cases of acute cholecystitis. All underwent pre-operative ultrasonography, complete blood cell count, liver function test and endoscopic retrograde cholangiopancreatography. Of those 44 had post-operative ultrasound within the first 2 d and again on the seventh day. In 35 cases of chronic cholecystitis, 31 of 32 cases with a pre-operative gallbladder (GB) wall thickness of less than 6 mm were successfully resected laparoscopically. All three cases with a GB wall thicker than 6 mm were converted to open cholecystectomy. In acute cholecystitis, the wall thickness of the laparoscopic cholecystectomy group ranged from 2 to 9 mm (average 4 mm) and the wall thickness of the conversion group was 4-7 mm (average 6 mm). Post-operative fluid accumulation was noted in 28 (63.6%) cases. There was no correlation between post-operative pyrexia, duration of post-operative pain, clinical complications and the presence of fluid accumulation in the GB fossa. However, of four cases with increasing fluid on the seventh day, three developed complications. We conclude that ultrasonography is valuable in chronic cholecystitis for selecting cases for laparoscopic cholecystectomy.

Carbon dioxide-enhanced ultrasonography of liver tumors

CO2 gas-enhanced ultrasonography was performed in 37 patients (47 studies) for the purpose of detecting small tumors and evaluating differential diagnosis. With conventional ultrasonography, 62 lesions were identified in 25 patients with HCC, 13 tumors were identified in eight patients with hemangioma, and multiple tumors were found in four patients with metastatic adenocarcinoma. CO2-enhanced ultrasonography detected five additional hemangiomas, 12 additional nodules in HCC, and the same number of metastatic nodules. The patterns of CO2 enhancement were characterized as homogeneous, heterogeneous, rim, internal spotted, negative, and mixed (more than one pattern in one lesion). The rim enhancement pattern was found to be specific for hemangioma. The internal spotted enhancement pattern was found exclusively in HCC. All the lesions that demonstrated negative enhancement were treated HCC. All the metastatic tumors demonstrated the mixed rim and internal spotted enhancement pattern. We suggest that CO2-enhanced ultrasonography is a useful tool in detecting small liver tumors. It can also help in the differentiation among various hepatic tumors.

Intravenous double-dose contrast computed tomography in the diagnosis of spinal arteriovenous malformations: report of four cases

Spinal IV double-dose computed tomography (DCT) followed by reformation imagings was performed on 4 patients. Three cases received double-dose contrast injections, one case received a conventional single dose contrast material. 'Dots' enhancement on axial CT scanning and 'vasculature-like' hyperdense enhancement on sagittal and coronal reformation imagings were found in four cases of spinal arteriovenous malformation (AVM). Two were at the cervical region and two at the thoracic level. Typical serpentine filling defects were noted in the myelogram of three cases of spinal AVM. One patient suffered from acute onset of paraplegia (case 2), requiring that she received immediate surgical intervention after DCT scanning without myelography. Time for the whole procedure lasted approximately 20 minutes. In addition DCT followed by reformation imaging may be used as a noninvasive preliminary screening procedure for spinal AVMs.