The relationship between stereopsis and monocular optokinetic optokinetic nystagmus after infantile cataracts

PURPOSE

Visual deprivation disrupting binocular development, such as that occurring with congenital cataract, is reported to cause asymmetric monocular optokinetic nystagmus (MOKN), as well as poor sensory and motorfusional outcome. We wanted to determine if symmetric MOKN could develop in cases of congenital cataract with good fusional outcome.

METHODS

We tested MOKN (with video and electro-oculographic recordings) and stereoacuity on 5 patients with good visual acuity and satisfactory ocular alignment after surgery for congenital cataract.

RESULTS

Stereoacuity was better than 50 seconds of arc in 1 case of monocular cataract and 2 cases of bilateral cataract. These case patients had symmetric MOKN. In a monocular cataract case, symmetric MOKN was observed in spite of questionable stereoacuity (at least 500 arc/s). One patient showed asymmetric MOKN, despite good visual acuity, and stereoacuity of 200 arc/s.

CONCLUSIONS

Patients with congenital cataract can have symmetric MOKN and good stereopsis. These cases suggest that MOKN symmetry develops along with good stereopsis, but the quality of stereopsis necessary for development of MOKN symmetry remains unclear.

A randomized comparison of prism adaptation and augmented surgery in the surgical management of esotropia associated with hypermetropia

OBJECTIVE

To compare both motor and sensory surgical outcomes for patients with esotropia associated with hypermetropia managed with an augmented surgery based on the average of the near deviation with and without correction vs preoperative prism adaptation.

METHODS

Forty-three patients with esotropia associated with hypermetropia entered a randomized prospective evaluation of augmented surgery (group A, 27 patients) versus prism adaptation (group P, 16 patients). The formula for augmenting the amount of the rectus muscle recession was based on the average of the near deviation with and without correction in group A, and the prism-adapted angle of deviation in group P.

RESULTS

In group A, postoperative deviations of 8 prism diopters (delta) or less at distance and at near were achieved in 24 patients (88%), and in 22 patients (81%), respectively. In nine prism responder patients, postoperative deviations of 8 delta or less at distance and at near were achieved in eight patients (89%). In seven nonresponder patients, postoperative deviations of 8 delta or less at distance and at near were achieved in six patients (86%). No significant difference between the two groups in terms of near and distance deviation at 1 and 3 months postoperatively were noted.

CONCLUSION

No significant difference existed in the motor outcomes between the two groups, or between the prism responder and prism nonresponder groups. Further detailed studies must be made in a large number of patients.

Combined effect of Interceed and 5-fluorouracil on delayed adjustable strabismus surgery

AIMS/BACKGROUND

To discover a more reliable method of performing delayed suture adjustment as a basis to investigate whether delayed adjustment actually provides more stable results. In order to prevent the formation of postoperative adhesions and delay the time of adjustment, an animal study was performed to determine the combined effect of physical barriers, Viscoat and Interceed, and a pharmacological agent, 5-fluorouracil (5-FU).

METHODS

38 rabbit eyes were divided into three groups. After recession of the superior rectus muscle (SRM), 5-FU was applied beneath and over the SRM in group 5-FU. Group I-f had Interceed and 5-FU and group I-fv, Interceed, 5-FU, and Viscoat. Delayed adjustment was performed once on each SRM at 1, 2, and 3 weeks postoperatively. The possible length and the necessary force to adjust as well as the degree of adhesions were recorded.

RESULTS

5-FU delayed the adjustment for up to 1 week after surgery in three out of four eyes. Combined use of Interceed and 5-FU could delay the adjustment for up to 1 week after surgery in three out of five eyes. Addition of Viscoat could delay the adjustment for up to 1 week after surgery in four out of five eyes. Adjustment was possible on only one of four eyes thereafter.

CONCLUSIONS

Combined use of Interceed, 5-FU, and Viscoat could delay the adjustment in rabbits until 1 week postoperatively.

Protective effects of capillarisin on tert-butylhydroperoxide-induced oxidative damage in rat primary hepatocytes

Capillarisin (Cap), a main constituent of Artemisia capillaris (Compositae), was studied for its antioxidant bioactivity. In the preliminary study, Cap expressed a antioxidant property by its capacity for quenching the free radicals of 1,1-diphenyl-2-picrylhydrazyl (DPPH). This antioxidant bioactivity of Cap was investigated further using a model of t-butylhydroperoxide (t-BHP)-induced cytotoxicity and genotoxicity in rat primary hepatocytes. Results presented here demonstrate that Cap, at concentrations of 0.01-1.00 mg/ml, significantly decreased the leakage of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) and the formation of malondialdehyde (MDA) induced by 30 min treatment of t-BHP (1.5 mM) in primary cultured rat hepatocytes. Cap also attenuated the t-BHP-induced diminution of glutathione (GSH) and high level of DNA repaired synthesis. These results lead to speculation that Cap presents inhibitory effects against t-BHP-caused cytotoxicity and genotoxicity in rat primary hepatocyte cultures at least via two distinct pathways, stabilizing the GSH system and quenching free radicals.

The Lancaster red-green test before and after occlusion in the evaluation of incomitant strabismus

BACKGROUND

Patients with incomitant strabismus can often fuse in a limited area of gaze. Prolongation of neurologically learned fusional vergence tone ("vergence adaptation") in and near this area can result in misleading measurements with standard clinical measures of strabismus. Monocular occlusion for at least 30 minutes eliminates most of the effect of vergence adaptation. The Lancaster red-green test provides an elegant and convenient map of incomitant strabismus. We investigated the efficacy of the Lancaster red-green test before and after monocular occlusion for the investigation of incomitant strabismus.

METHODS

We retrospectively studied the results of the Lancaster red-green test in 6 patients with incomitant vertical strabismus in whom we suspected that vergence adaptation might be distorting the pattern of deviation. The test was performed before and after monocular occlusion for 30 to 60 minutes, and the preocclusion and postocclusion results were compared.

RESULTS

In the 6 cases studied, the Lancaster red-green test showed at least a 5-PD increase in the hyperdeviation, after monocular occlusion. The increases were mostly in primary gaze and downgaze, which tended to regularize the pattern of deviation.

CONCLUSIONS

The combination of monocular occlusion and the Lancaster red-green test is useful for uncovering the effect of vergence adaptation. Such results may often simplify the planning of surgical correction because the incomitance usually decreases after monocular occlusion, making it less likely that surgery will worsen the alignment in the area previously fused. We recommend that monocular occlusion should be considered when planning surgery or even prism correction for incomitant deviations, especially when the initial Lancaster red-green test shows an unexpected incomitant pattern where there is fusion in 1 direction of gaze but not in others.

Cloning and expression of a G protein-linked acetylcholine receptor from Caenorhabditis elegans

We have isolated a cDNA clone from the nematode Caenorhabditis elegans that encodes a protein of greatest sequence similarity to muscarinic acetylcholine receptors. This gene codes for a polypeptide of 682 amino acids containing seven putative transmembrane domains. The amino acid identities, excluding a highly variable middle portion of the third intracellular loop, to the human m1-m5 receptors are 28-34%. When this cloned receptor was coexpressed with a G protein-gated inwardly rectifying K+ channel (GIRK1) in Xenopus oocyte, acetylcholine was able to elicit the GIRK current. This acetylcholine-induced current was substantially inhibited by the muscarinic antagonist atropine in a reversible manner. However, another muscarinic agonist oxotremorine and antagonists scopolamine and pirenzepine had little or negligible effects on this receptor. Taken together, these results suggest that the cloned gene encodes a G protein-linked acetylcholine receptor that is most similar to but pharmacologically distinct from muscarinic acetylcholine receptors.

Bilateral ocular ischemic syndrome secondary to giant cell arteritis progressing despite corticosteroid treatment

PURPOSE

To report the development of a bilateral ocular ischemic syndrome despite corticosteroid treatment in a patient with giant cell arteritis.

METHOD

Case report.

RESULTS

Despite receiving high-dose intravenous methylprednisolone and oral prednisone for biopsy-proven giant cell arteritis that presented as a severe anterior ischemic optic neuropathy in the right eye, a patient developed progressive ocular ischemia in that eye as well as an ocular ischemic syndrome in the fellow eye.

CONCLUSIONS

Some patients with giant cell arteritis, possibly patients with other underlying systemic vasculopathies, are refractory to what should be adequate treatment with systemic corticosteroids and may develop a bilateral ocular ischemic syndrome.

Results and prognostic factors in the retreatment of locally recurrent nasopharyngeal carcinoma

PURPOSE

To review the results and evaluate the prognostic factors in the retreatment of locally recurrent nasopharyngeal carcinoma.

METHODS AND MATERIALS

We reviewed the records of 74 patients with locally recurrent nasopharyngeal carcinoma treated at the University of California, San Francisco between 1957 and 1995. The histologic types included squamous cell carcinoma in 6 (8.1%), nonkeratinizing carcinoma in 48 (64.9%), and undifferentiated carcinoma in 20 (27%) cases. The site of recurrence was in the primary in 46 (62.2%), in the neck nodes in 20 (27%), and in both sites in 8 (10.8%) patients. The recurrent disease was Stage I in 10 (13.5%), Stage II in 16 (21.6%), Stage III in 20 (27%), and Stage IV in 28 (37.9%) patients. Thirty-seven (50%) patients developed recurrence within 2 years and 58 (78.4%) within 5 years after initial treatment. Radiotherapeutic techniques used in the retreatment of primary recurrence consisted of external beam radiotherapy (EBRT), intracavitary brachytherapy, heavy-charged particle beam, and gamma knife, alone or in combination. Reirradiation doses ranged from 18 to 108 Gy, with a median dose of 60 Gy. Treatment of recurrent neck nodes consisted of radical neck dissection (RND) +/- intraoperative radiotherapy (IORT), or EBRT +/- hyperthermia, or chemotherapy +/- hyperthermia. Chemotherapy was used in 22 (30%) patients. Median follow-up was 20 months (range: 2 to 308 months).

RESULTS

The 3-, 5-, and 10-year actuarial overall survival following retreatment were 49, 37, 18%, respectively. Thirty-six patients (49%) were free of further local-regional recurrence after retreatment. The 3-, 5-, and 10-year local-regional progression-free rates were 52, 40, and 38%, respectively. On univariate analysis, histologic type (p < 0.0001), interval to recurrence (p = 0.034), and treatment modality for early-stage disease (p = 0.01) were significant prognostic factors for overall survival, with age being marginally significant (p = 0.053). For local-regional progression-free rate, only histology was significant (p = 0.035). On multivariate analysis, age (p = 0.026), histology (p = 0.015), and interval to recurrence (p = 0.030) were significant for overall survival, and only histology (p = 0.002) and presence of complications (p = 0.016) were significant for local-regional progression-free rate. Of the 64 reirradiated patients, late complications were documented in 29 (45%) patients. The late complications were permanent in 21 (33%) and severe in 15 (23%) patients.

CONCLUSION

Retreatment using radiotherapy alone or in combination with other treatment modalities can achieve long-term local-regional control and survival in a substantial proportion of patients with locally recurrent nasopharyngeal carcinoma. Age, histology, and interval to recurrence were independent prognostic factors for overall survival, but only histology and presence of complications were significant for local-regional progression-free rate.

Optic neuropathy associated with ethambutol in Koreans

Ethambutol is a useful first line antituberculous drug, but can cause significant visual impairment. In order to determine the clinical manifestations of optic neuropathy associated with ethambutol, and the margin of drug safety in Koreans, we investigated ten men and four women, diagnosed between 1995 and 1997 at Seoul Municipal Boramae Hospital as suffering from ethambutol toxicity. After determining their history, including the period during which ethambutol had been administered, and its dose, a complete eye examination was performed, including measurement of best-corrected visual acuity, pupillary examination, color vision, fundus examination and a test of visual field. Ocular ethambutol toxicity was observed at a dose as low as 12.3 mg/kg. Abnormal ophthalmic findings include decreased visual acuity and abnormal visual field, especially in the central scotoma, and abnormal color perception. In conclusion, ethambutol at a low dose can cause optic neuropathy, and for the early detection of this, a color vision test is important.

Optic neuropathy associated with mitochondrial tRNA[Leu(UUR)] A3243G mutation

PURPOSE/BACKGROUND

To report the association of optic neuropathy and mitochondrial tRNA[Leu(UUR)] A3243G mutation which is known to be responsible for MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes), diabetes mellitus with deafness, and progressive external opthalmoplegia. Pigmentary retinopathy, opthalmoparesis, and ptosis have been relatively frequently reported to be associated with the mutation in the literature. However, optic atrophy has rarely been reported to be associated with the mutation.

METHODS

Analyses including measurement of the corrected visual acuity, color vision, pupillary examination, funduscopic examination, visual field, visual evoked potential, and brain imaging study were performed in our two patients with the mutation.

RESULTS

In disagreement with previous reports, this study revealed the association between optic neuropathy and the mutation in the two patients.

CONCLUSION

There might be some degree of optic neuropathy related to the tRNA[Leu(UUR)] A3243G mutation. Thus more detailed ophthalmologic examination should be done to detect optic neuropathy.

Nucleotide sequence and phylogenetic analysis of Newcastle disease virus isolates from recent outbreaks in Taiwan

Portions of the hemagglutinin neuraminidase (HN) gene of Newcastle disease virus (NDV) isolates from two recent outbreaks were sequenced to investigate epidemiology of this disease in Taiwan. These NDV isolates were all viscerotropic velogenic according to the clinical lesions produced in chickens. Sequence data were obtained from 14 NDV isolates (12 from 1995 and 2 from 1984). All isolates differed in their nucleotide sequences (from 0.3 to 15.3%), and represented potentially different strains of NDV. Phylogenetic analysis revealed that these isolates are closely related to viruses isolated from Japan and Malaysia. Some viruses isolated in 1995 appeared to evolve from viruses isolated in 1984. The results suggest that the 1995 outbreak of Newcastle disease (ND) in Taiwan may have been caused by multiple strains of velogenic NDV that have cocirculated in Taiwan for some time. Moreover, NDV isolates from racing pigeons were very similar to isolates from chickens in the same period, suggesting that both domestic and free-living birds were involved in the spread of ND in Taiwan.

The microevolution of mouse salivary androgen-binding protein (ABP) paralleled subspeciation of Mus musculus

Mouse salivary androgen-binding protein (ABP) is a major secretory product of the submaxillary glands. Although it is a common salivary protein among rodents generally, the function of ABP has yet to be determined. Here we report a comparison of the DNA coding sequences and putative amino acid sequences they determine for the three common alleles of the Alpha subunit gene (Abpa), alleles that appear to be diagnostic for the three subspecies of Mus musculus. Three other unique sequences were found in the species M. caroli, M. spretus, and M. spicilegus. Comparison of the six sequences shows that 8 of the 20 base substitution sites produce a high degree of variability in amino acids 32, 33, 36, and 39, a variability that creates unique sequence combinations in each species and subspecies. We compare the possibilities that selection or genetic drift caused this unusual microevolution and argue that selection is the more likely explanation. We speculate on the potential significance of this with respect to the proposal that ABP is involved in assortive mate kin selection.

Delayed reattachment of extraocular muscles in rabbits using thin polytetrafluoroethylene

BACKGROUND AND OBJECTIVE

The authors attempted to find a way to perform reliable delayed suture adjustment so that surgeons can investigate whether delayed adjustment actually gives more reliable and stable results. To prevent the formation of postoperative adhesions and delay the time of adjustment, the authors used polytetrafluoroethylene (PTFE) as a mechanical barrier.

MATERIALS AND METHODS

PTFE was placed between the free muscle end and the sclera as a physical barrier in 16 rabbits.

RESULTS

PTFE could delay the adjustment for up to 4 weeks after surgery in 4 of 10 eyes in each group. After removal of PTFE, adjustment was possible up to 12 weeks because there was no adhesion between the muscle and the PTFE.

CONCLUSION

Adjustment could be delayed up to 4 weeks in 40% of the experimental eyes using PTFE as a physical barrier.

Carbon monoxide poisoning as an epigenetic factor for Leber's hereditary optic neuropathy

A 45-year-old Korean woman visited our hospital complaining of poor vision after carbon monoxide (CO) poisoning. We have confirmed the presence of a point mutation at position 11778 in the ND4 gene of mitochondrial DNA. This case suggests that CO poisoning may precipitate the clinical expression of Leber's hereditary optic neuropathy (LHON). To our knowledge, this would be the first case report of clinical expression of LHON precipitated by CO poisoning.

Inhibitory effect of atractylon on tert-butyl hydroperoxide induced DNA damage and hepatic toxicity in rat hepatocytes

Atractylon, a main sesquiterpenic constituent of Atractylodes rhizomes, was studied for the mechanism of its inhibitory effects on the tert-butyl hydroperoxide (t-BHP)-induced cytotoxicity and lipid peroxidation in primary culture of rat hepatocytes. In the preliminary study, atractylon showed an effective antioxidant property tested by its capacity for quenching 1,1-diphenyl-2-picrylhydrazyl radical (DPPH). Further investigations showed that atractylon at the concentrations of 0.01, 0.1 and 1.0 mg/ml decreased the formation of malondialdehyde (MDA), leakage of lactate dehydrogenase (LDH) and alanine aminotransferase (ALT) and repair synthesis of DNA induced by 30-min treatment of t-BHP (1.5 mM) in primary cultured rat hepatocytes. Addition of atractylon also attenuated the genotoxicity of t-BHP evaluated by unscheduled DNA synthesis. The sum of the results suggested that the protective effect of atractylon against oxidative stress induced by t-BHP is via its ability to quench free radicals.

Use of physical barriers for delayed adjustable strabismus surgery: the effect of interceed and polyglactin 910 mesh

AIMS/BACKGROUND

In the course of adjustable strabismus surgery there is only a limited period after surgery before the formation of firm adhesions prevents successful adjustment. To determine if this period could be increased by the interposition of suitable physical barriers, the use of Interceed and polyglactin 910 mesh was investigated in an animal model.

METHODS

A total of 39 rabbit eyes were divided into three groups. After recession of the superior rectus muscle (SRM), balanced salt solution was applied to the control group between the free muscle end and the sclera; in each of the two experimental groups, Interceed and polyglactin 910 mesh were applied. Delayed adjustment was performed once on each SRM at 1, 2, or 3 weeks postoperatively. The length and force of the adjustment, the degree of adhesions, and the degree of fibrous proliferation were recorded.

RESULTS

Adjustment was not possible in any of the eyes in the control group. At 1 week postoperatively, adjustment was possible in four out of five eyes with Interceed and in three out of five eyes with polyglactin 910 mesh as a physical barrier.

CONCLUSIONS

Interceed may be clinically useful in delaying the timing of adjustment up to 1 week. Further study of the use of other materials could be carried out to see if it was possible to delay the timing of adjustment for more than 1 week.

Concurrent 5-fluorouracil, daily low-dose cisplatin, and radiotherapy in stage IIIB cervical cancer. A phase II prospective study

Between June 1987 and May 1991, 30 patients with Stage IIIB cervical cancers were treated using synchronous radiotherapy, 5-fluorouracil (5-FU), and daily low-dose cisplatin. External radiotherapy (3,600-3,960 cGy) was given to the whole pelvis in 4 weeks. Two courses of intracavitary brachytherapy were given 2 weeks later. Parametrial boost was then given. Continuous infusion of 5-FU 750 mg/m2 was given for 5 days during the first and third week of pelvic irradiation. Cisplatin (6 mg/m2) was given 30 min before every irradiation in the second and fourth week. The complete response rate was 87%. The 3-year local control rate was 77%. The 3-year overall and disease-free survival rate was 66% and 56%, respectively. Distant metastases were the major causes of treatment failure. Toxicities were acceptable. Our preliminary results indicate that this synchronous combination treatment is feasible. Further follow-up is required to determine whether this regimen has a genuine favorable impact on survival and chronic toxicity.

Complete nucleotide sequence, structural organization, and an alternatively spliced exon of mouse h1-calponin gene

From a CC1.2 embryonic stem cell genomic library, we isolated and sequenced a 10.4-kb DNA segment (GenBank/EMBL Data Bank accession number L49022) containing the entire gene encoding mouse h1-calponin, an actin-associated smooth muscle-specific protein and a potential modulator of contraction. Sequence data revealed that there are seven exons and six introns in the h1-calponin gene. Determined by primer extension mapping of the RNA transcripts, the transcription of h1-calponin gene initiates at the same site in stomach, urinary bladder and pregnant uterus smooth muscles. The genomic organization suggests that the previously identified alpha- and beta-calponin isoforms are produced by splicing of exon 7 at two alternative acceptor sites. Isolation and structural characterization of the h1-calponin gene provides information to further investigate the expression regulation of this smooth muscle-specific gene.

Combined study on the causes of strabismus after the retinal surgery

Extraocular muscle imbalance and diplopia after retina surgery have been previously reported, but the etiology is still controversial. In order to better understand the cause of strabismus after retinal surgery, the authors retrospectively studied 30 patients with persistent strabismus following retinal surgery and combined the result about seven patients of strabismus after retinal surgery in the previous report. Results showed multiple etiologies for the strabismus. Causes of strabismus included fat adherence syndrome (14 patients), non-specific restrictive adhesion (11), displacement of superior oblique tendon (2), scleral explant interfering with ocular motility (1), lost or slipped muscle with adhesion (2), sensory strabismus (2), macular pucker causing ectopic fovea (2), and previous strabismus before the retinal surgery (3). Knowledge of the varieties of abnormalities that can cause strabismus and diplopia will help both the retina and strabismus surgeon prevent and treat strabismus after retinal surgery.

Surgical techniques of strabismus

Improvements in the management of strabismus are largely dependent on making the specific diagnosis and differentiating patterns of strabismus. This finding is especially true in the management of superior oblique paresis because there are various types. Recent observation suggests that superior oblique paresis may be associated with a lax superior oblique tendon and that the cause of the paresis is not always neurogenic. Some authorities have suggested using the traction test of the superior oblique to determine whether the superior oblique tendon is lax. If it is lax, the treatment of choice would be a tightening procedure of the superior oblique such as the superior oblique tuck. Adjustable-suture strabismus surgery has reduced the incidence of repeat operations; however, adapting the procedure to the fornix incision has been difficult. The use of a scleral traction suture that retracts the conjunctiva to expose the muscle suture area has been useful for fornix surgery. The rectus muscles supply circulation to the anterior segment via the anterior ciliary vessels, which are routinely interrupted during strabismus surgery. Various procedures have recently been described to preserve the anterior ciliary vessels, and these procedures will be useful in patients who are predisposed to anterior segment ischemia. In the 1950s, inferior oblique weakening procedures were deemed dangerous and unpredictable. Recent advances in the understanding of inferior oblique physiology and fascial relationships have inspired the development of a new inferior oblique weakening strategy--the anteriorization procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

A modified method for obtaining large amounts of high titer polyclonal ascites fluid

When limited amounts of antigens are available, it is often difficult to obtain large quantities of polyclonal antisera. Although antisera can be raised in small rodents, yields are usually small. To circumvent these problems, we have designed a modified method for generating polyclonal ascites fluid (AF). Using the appropriate strain of mice and adjuvant, we generated high serum titers by injection of 1-100 micrograms of protein. Following i.p. injection of compatible sarcoma cells, 13-19 ml of high titer (1:1000-1:20,000), polyclonal ascites fluid were obtained from each mouse. Similar results were obtained using nine different antigens.

A new in vivo assay of the reactions of microencapsulated human tumor cells to chemotherapeutic drugs

A new cell culture modality had already been established in our laboratory. Using this model, living KB and GBM 8401 tumor cells grew and proliferated exponentially in semipermeable microcapsules, implanted in vivo. The culture method was designed as a modality for a predictive anticancer drug sensitivity test. Its advantages included providing a three-dimensional growth and in vivo supply of nutrients. Tumor cell sensitivity to drugs can be assessed in vivo. The assay is applicable to virtually all histological types of human tumor cells. Using this technique, anticancer drug sensitivity tests of KB and GBM 8401 cells were evaluated. The results showed that such encapsulated cells grew and proliferated rapidly. In addition, the proliferation of KB cells was more rapid than that of GBM 8401 cells under conventional monolayer and in vivo microcapsule culture states. They were very sensitive to adriamycin and fluorouracil, and relatively resistant to cyclophosphamide while cultured in vitro. The viability percentage of microencapsulated KB cells cultured in vivo for two weeks was around 80-90%, roughly similar to that of the same cells conventionally cultured in vitro. However, the proliferation rates of encapsulated KB and GBM 8401 cells in vivo were significantly inhibited by all the drugs tested, with KB cells inhibited more significantly than GBM 8401. These results also suggest that some anticancer drugs needing to be bioactivated in vivo had better test results by this technique, and thus false negative results could be excluded. Also, the good repair capacity of microcapsules implanted in vivo, for damaged tumor cells previously incubated with chemotherapeutic drugs, appears to provide a much better environment for cell growth because much essential nourishment can be supplied. The inhibition percentage of fluorouracil to encapsulated cancer cells from patients with adenocarcinoma of the colon was also tested; they were 69.8% in vivo and 76.5% in vitro. This fast, relatively inexpensive in vivo model can be used to screen various anticancer drugs and help clinical oncologists to select the most effective agents for individual patients.

Evaluation of a rapid tetrazolium-based colorimetric assay for selecting anticancer drugs

A rapid colorimetric microtiter assay was used in this study to analysis drug cytotoxicity. Through the reduction of tetrazolium salt, MTT [3-(4, 5-dimethyl-thiazol-2-yl) 2,5-diphenyl tetrazolium bromide], by living cells to form a blue formazan product. The level of MTT cleavage by viable cells of various origins was found to be in direct proportion to the number of cells (between 500-10,000 cells/well). By MTT methods, the growth profile and chemosensitivity of 4 human tumor cell lines (KB, Hep-2, HA22T, and CoLo205) to 4 anticancer drugs (adriamycin, 5-fluorouracil, 6-mercaptopurine and cyclophosphamide) were assessed. Results from this assay were compared with data assimilated simultaneously by dye exclusion and clonogenic assay. In general, good correlation was observed among the clonogenic, dye exclusion and MTT assays for continuous drug exposures, yet the MTT assay was more rapid in testing in vitro chemosensitivity against human tumor cell lines. The dye exclusion assay was the most sensitive, followed by the clonogenic and then the MTT assays. The ID50 values obtained from the MTT assay were approximately 3 to 5 times lower than those from the other two methods. Based on these studies, MTT assay appears to be a rapid, convenient, economical and reasonable tool in the initial-stage screening of large number of the in vitro anticancer drugs.

The effect of cryotherapy on proliferative vitreoretinopathy (PVR)

Cryotherapy is implicated for inducing or aggravating proliferative vitreoretinopathy (PVR) by releasing retinal pigment epithelial (RPE) cells. These are based on the fact that PVR rarely occurs in a non-operated eye, and many of the PVR patients have received cryotherapy during surgery. Nonetheless, eyes with diathermy also developed PVR, and although there have been many experiments, the effect of cryotherapy on inducing PVR has not been proven experimentally in the living eye. We made retinal tears in living rabbit eyes, and applied cryotherapy on one eye of each rabbit. The result was compared histologically with the contralateral noncryothermized control eye. There was no statistically significant difference between the two groups concerning the migration of RPE, and the proliferation of RPE. Although the formation of an epiretinal membrane was more obvious in the cryothermized group, the difference was not statistically significant.

Microencapsulation [corrected] of tumor cells and assay for selecting anticancer drugs

A microencapsulation of living tumor cells by an improved membrane and droplet forming technique was established in our laboratory. This semipermeable microencapsulating membrane was impermeable to serum albumins (M.W. 66,000 or 45,000) and human hemoglobin (M.W. 64,000), but permitted passage of low molecular weight substances (alpha-Lactalbumin, or Trypsinogen; M.W. 14,200 or 24,000). The in vivo results showed that microencapsulated tumor cell lines (KB, human oral epidermoid cell; P-388 lymphocytic leukemia; GBM 8401/TSGH, glioma) and human colorectal carcinoma cells grew and proliferated exponentially within twenty days. The in vivo growth exhibited better than that in vitro. Histological and morphological findings of these four different kinds of tumor cells are similar to those of original tumor cells. Treatment of the microencapsulated tumor cells (MTC) with cytotoxic drugs (adriamycin, 5-fluorouracil and cyclophosphamide) in vitro showed no significant difference in percent inhibition (p greater than 0.05) between the encapsulated and non-encapsulated cells. The in vivo data indicated that different anti-cancer drugs had different inhibition effects. The results showed that the MTC model was useful for screening an appropriate cytotoxic drug and could be applied to clinical medicine in the near future.

Effect of storage temperature and pH on the stability of antimicrobial agents in MIC trays

Twelve antimicrobial agents, ampicillin, aztreonam, cefamandole, cefazolin, cefonicid, ceforanide, ceftazidime, ceftizoxime, ceftriaxone, cefuroxime, ciprofloxacin, and norfloxacin, were prepared at pH 6.80 and 7.31 in microdilution trays for storage at 4, -10, -25, and -70 degrees C and for weekly susceptibility testing. All 12 drugs had stable biological activity when stored at -70 degrees C for 1 year. All but ampicillin and aztreonam were stable at -25 degrees C. Storage at -10 degrees C was least satisfactory. Desiccation occurred at 4 degrees C, but short-term storage at this temperature is possible since the antimicrobial agents are stable for up to several months.