Dementia with Lewy bodies treated with rivastigmine: effects on cognition, neuropsychiatric symptoms, and sleep

Dementia with Lewy bodies (DLB) is a common cause of the dementia syndrome. Symptomatic treatment of the fluctuating cognition, visual hallucinations, and sleep disturbance that characterize this condition is challenging; neuroleptics are relatively contraindicated. We describe eight patients fulfilling the consensus diagnostic criteria for probable DLB who were treated with rivastigmine. Clinical features rated were: cognition by the Modified Mini-Mental State Examination (3MS); and behavioral and psychiatric symptoms by the Neuropsychiatric Inventory (NPI). Additional information was obtained from family and nursing reports. Seven patients showed resolution or improvement in cognition and neuropsychiatric symptoms as demonstrated by improvement in their 3MS and NPI scores. They also became more independent in mobility and activities of daily living, and the majority returned to live in their own home. Of the seven patients with sleep disruption, six improved. One case had no improvement in his symptomatology and the rivastigmine was stopped. Outcomes in this case series suggest that rivastigmine is well tolerated in clinical practice.

Evidence for alternate splicing within the mRNA transcript encoding the DNA damage response kinase ATR

Proper cellular response to genotoxic insult often requires the activity of one or more members of a family of high-molecular weight protein kinases referred to as phosphatidylinositol-3 kinase (PIK)-like proteins. While catalytic activity is an indispensable part of PIK-like protein function, little is currently known about factors that control their activity and/or functions. This deficiency stems, in large part, from our lack of knowledge concerning functionally significant subdomains within the large non-catalytic domain of these proteins. We have determined that the transcript encoding the PIK-like protein ATR undergoes alternate splicing within the region of the mRNA encoding its non-catalytic domain. This conclusion is based on the sequencing of a human expressed sequence tag clone encoding a portion of the ATR cDNA, and is supported by the results of reverse transcriptase-polymerase chain reaction (RT-PCR) assays conducted on total and polyA+ RNA, as well as sequencing of cloned RT-PCR products. Cloning and sequencing of a segment of human genomic DNA indicated that this event arises from splicing of a single 192 bp exon within the ATR gene. Analysis of several human tissues indicated that alternate ATR transcripts are differentially expressed, suggesting that this region of the ATR protein may be of functional importance.

The ZNF217 gene amplified in breast cancers promotes immortalization of human mammary epithelial cells

The functional consequences of overexpression of a candidate oncogene on chromosome 20q13.2, ZNF217, were examined by transducing the gene into finite life span human mammary epithelial cells (HMECs). In four independent experiments, ZNF217-transduced cultures gave rise to immortalized cells. HMECs that overcame senescence initially exhibited heterogeneous growth and continued telomere erosion, followed by increasing telomerase activity, stabilization of telomere length, and resistance to transforming growth factor beta growth inhibition. The incremental changes in telomerase activity and growth that occurred in ZNF217-transduced cultures after they overcame senescence were similar to the conversion pattern we have described previously in rare HMEC lines immortalized after exposure to a chemical carcinogen. Aberrant expression of ZNF217 may be selected for during breast cancer progression because it allows breast cells to overcome senescence and attain immortality.

The involvement of hydrogen peroxide in the differentiation of secondary walls in cotton fibers

H2O2 is a widespread molecule in many biological systems. It is created enzymatically in living cells during various oxidation reactions and by leakage of electrons from the electron transport chains. Depending on the concentration H2O2 can induce cell protective responses, programmed cell death, or necrosis. Here we provide evidence that H2O2 may function as a developmental signal in the differentiation of secondary walls in cotton (Gossypium hirsutum) fibers. Three lines of evidence support this conclusion: (a) the period of H2O2 generation coincided with the onset of secondary wall deposition, (b) inhibition of H2O2 production or scavenging the available H2O2 from the system prevented the wall differentiation process, and (c) exogenous addition of H2O2 prematurely promoted secondary wall formation in young fibers. Furthermore, we provide support for the concept that H2O2 generation could be mediated by the expression of the small GTPase Rac, the accumulation of which was shown previously to be strongly induced during the onset of secondary wall differentiation. In support of Rac's role in the activation of NADPH oxidase and the generation of reactive oxygen species, we transformed soybean (Glycine max) and Arabidopsis cells with mutated Rac genes. Transformation with a dominantly activated cotton Rac13 gene resulted in constitutively higher levels of H2O2, whereas transformation with the antisense and especially with dominant-negative Rac constructs decreased the levels of H2O2.

A built-in arginine finger triggers the self-stimulatory GTPase-activating activity of rho family GTPases

Signal transduction through the Rho family GTPases requires regulated cycling of the GTPases between the active GTP-bound state and the inactive GDP-bound state. Rho family members containing an arginine residue at position 186 in the C-terminal polybasic region were found to possess a self-stimulatory GTPase-activating protein (GAP) activity through homophilic interaction, resulting in significantly enhanced intrinsic GTPase activities. This arginine residue functions effectively as an "arginine finger" in the GTPase activating reaction to confer the catalytic GAP activity but is not essential for the homophilic binding interactions of Rho family proteins. The arginine 186-mediated negative regulation seems to be absent from Cdc42, a Rho family member important for cell-division cycle regulation, of lower eukaryotes, yet appears to be a part of the turn-off machinery of Cdc42 from higher eukaryotes. Introduction of the arginine 186 mutation into S. cerevisiae CDC42 led to phenotypes consistent with down-regulated CDC42 function. Thus, specific Rho family GTPases may utilize a built-in arginine finger, in addition to RhoGAPs, for negative regulation.

Development in release testing of topical dosage forms: use of the Enhancer Cell with automated sampling

The aim of this study was to evaluate an automated method using the Enhancer Cell and compare the release of the corticosteroid triamcinolone acetonide (TA) from commercial semisolid formulations. The method used a modified USP Apparatus 2 using the Enhancer Cell in 200 ml capacity flasks instead of the standard 900 ml flasks. The additional equipment included an adapter plate to position the flasks in the center, a cover to reduce the receptor phase evaporation and smaller sized (1/4 in.) shaft and collets. All products were evaluated prior to their expiration date. Effects of system variables such as the temperature and composition of the receptor medium, stirring speed, and the choice of membrane on the drug release were evaluated. Statistical analysis was carried out using SAS Ver. 6.07 and the slopes and intercepts (of the cumulative release/unit area versus square root of time plots) were compared. TA release was a linear function of the square root of time (P < or = 0.0001), in accordance with Higuchi's model (r2 > or = 0.9 in most cases). Temperature (32 and 37 degrees C) did not affect the drug release (P > 0.32) but a significantly higher release rate was observed (P < or = 0.0001) at 50 degrees C. Stirring speed (50, 100, 200 rpm) (P > 0.26) and receptor media composition (38 and 76% ethanol) (P > 0.68) did not significantly alter the release rates. Membrane selection (regenerated cellulose, polyethylene, and rat skin) was found to be a significant variable (P < or = 0.004). This study demonstrates the use of the Enhancer Cell as an automated quality control tool in the in vitro release testing procedure for semisolid drug formulations.

Analysis of the mechanisms of action of the Saccharomyces cerevisiae dominant lethal cdc42G12V and dominant negative cdc42D118A mutations

The Saccharomyces cerevisiae Cdc42p GTPase is localized to the plasma membrane and involved in signal transduction mechanisms controlling cell polarity. The mechanisms of action of the dominant negative cdc42(D118A) mutant and the lethal, gain of function cdc42(G12V) mutant were examined. Cdc42(D118A,C188S)p and its guanine-nucleotide exchange factor Cdc24p displayed a temperature-dependent interaction in the two-hybrid system, which correlated with the temperature dependence of the cdc42(D118A) phenotype and supported a Cdc24p sequestration model for the mechanism of cdc42(D118A) action. Five cdc42 mutations were isolated that led to decreased interactions with Cdc24p. The isolation of one mutation (V44A) correlated with the observations that the T35A effector domain mutation could interfere with Cdc42(D118A, C188S)p-Cdc24p interactions and could suppress the cdc42(D118A) mutation, suggesting that Cdc24p may interact with Cdc42p through its effector domain. The cdc42(G12V) mutant phenotypes were suppressed by the intragenic T35A and K183-187Q mutations and in skm1Delta and cla4Delta cells but not ste20Delta cells, suggesting that the mechanism of cdc42(G12V) action is through the Skm1p and Cla4p protein kinases at the plasma membrane. Two intragenic suppressors of cdc42(G12V) were also identified that displayed a dominant negative phenotype at 16 degrees C, which was not suppressed by overexpression of Cdc24p, suggesting an alternate mechanism of action for these dominant negative mutations.

Alagille syndrome is caused by mutations in human Jagged1, which encodes a ligand for Notch1

Alagille syndrome is an autosomal dominant disorder characterized by abnormal development of liver, heart, skeleton, eye, face and, less frequently, kidney. Analyses of many patients with cytogenetic deletions or rearrangements have mapped the gene to chromosome 20p12, although deletions are found in a relatively small proportion of patients (< 7%). We have mapped the human Jagged1 gene (JAG1), encoding a ligand for the developmentally important Notch transmembrane receptor, to the Alagille syndrome critical region within 20p12. The Notch intercellular signalling pathway has been shown to mediate cell fate decisions during development in invertebrates and vertebrates. We demonstrate four distinct coding mutations in JAG1 from four Alagille syndrome families, providing evidence that it is the causal gene for Alagille syndrome. All four mutations lie within conserved regions of the gene and cause translational frameshifts, resulting in gross alterations of the protein product Patients with cytogenetically detectable deletions including JAG1 have Alagille syndrome, supporting the hypothesis that haploinsufficiency for this gene is one of the mechanisms causing the Alagille syndrome phenotype.

Effect of varying drug loading on particle size distribution and drug release kinetics of verapamil hydrochloride microspheres prepared with cellulose esters

Microspheres containing two different drug loadings of a calcium channel blocker, verapamil hydrochloride, were prepared with three different cellulose esters namely cellulose acetate (CA), cellulose acetate propionate (CAP) and cellulose acetate butyrate (CAB) of approximately similar molecular weights using the emulsion-solvent evaporation method. Increasing the drug loading from 33.3 to 50% w/w increased the geometric mean diameter of the microspheres as well as the T50% values, i.e. time required to release 50% of the drug from microspheres prepared with all the three cellulose esters. Drug release from the microspheres was affected by the nature of polymer. Mathematical modelling of drug release data by fitting the data to various equations revealed that the data did not fit the conventional Higuchi's and Baker-Lonsdale's models for drug release from spherical matrices. Instead, the data fitted the log-probability and the Weibull models quite well.

Prognostic value of c-erbB-2 and epidermal growth factor receptor in stage A1 (T1a) prostatic adenocarcinoma

OBJECTIVE

To determine whether the presence or absence of the oncoproteins epidermal growth factor receptor (EGFR) and c-erbB-2 could predict tumour behaviour.

PATIENTS AND METHODS

Tissue from 45 stage A1 (T1a) prostatic adenocarcinomas from patients with a mean age of 65 years were immunostained for EGFR (12E) and c-erbB-2 (NCL-CB11). Their expression in the tumour and surrounding benign hyperplastic epithelium was correlated with each other and with survival.

RESULTS

Forty percent (18 of 45) and 36% (16 of 45) of patients respectively were EGFR and c-erbB-2 positive in the tumour. Expression of these tyrosine kinase oncogenes was not confined to the tumour and the surrounding hyperplastic prostate was also positive for EGFR in 76% (34/45) of patients and for c-erbB-2 in 16% (11 of 45). EGFR and c-erbB-2 expression was weakly associated in both benign and malignant epithelium. Statistical analysis of survival showed that tumour c-erbB-2 expression was associated with a significantly worse prognosis (exact two tailed P = 0.0316), whereas no significant association was observed between EGFR expression and survival (P = 0.737).

CONCLUSION

As c-erbB-2 expression increases the rate of dying by 4.2 times, recording its expression by these tumours may be useful in selecting patients who would benefit from treatment in stage A1 (T1a) disease.

The measurement of the lateralization of narrow bands of noise using an acoustic pointing paradigm: the effect of sound-pressure level

The effects of varying interaural time delay (ITD) and interaural intensity difference (IID) were measured in normal-hearing subjects as a function of eleven frequencies and at sound-pressure levels (SPL) from 60 to 90 dB SPL and at 25-dB sensation level. Using an "acoustic" pointing paradigm, the IID of a 500-Hz narrow-band (100 Hz) noise (the "pointer") was varied by the subject to coincide with that of a "target" ITD stimulus. ITDs of 0, +/- 200, and +/- 400 microseconds were obtained through total waveform delays of narrow-band noise (NBN), including envelope and fine structure. The results of this experiment confirm the traditional view of binaural hearing for like stimuli: There is little perceived displacement away from 0 IID at frequencies of 1250 Hz and above. In the low frequencies, subjects required IIDs greater than the expected 10 dB to perceive a fully lateralized image, and they varied in the maximum value of IID that they required, regardless of frequency. Our subjects did not always perceive the intracranial locations of ITD targets symmetrically: When the signal was delayed to one ear, the resultant matching IID was often different in magnitude than for the same ITD target delayed to the opposite ear for the identical frequency. The results of two subjects suggested that people with asymmetric normal hearing have adapted to their asymmetry for lateralization tasks: The subjects were found to lateralize toward the ear with the greater SPL stimulus, regardless of the ear to which the signal was delayed, when signals of equal SL were presented, and toward the leading ear when signals of equal SPL were presented (unequal SL). Increasing the presentation levels above 60 dB SPL had an effect on the perception of high-frequency ITD targets: As the intensity level increased, the slopes of the IID versus ITD functions increased indicating better discrimination of ITD. This study is in agreement with other studies in providing strong evidence of individual differences in lateralization experiments. These individual differences might be attributable to differential sensitivity to ambiguous time stimulus cues, differential task sensitivity, age effects, threshold asymmetries, or criterion variability.

Evaluation of Preflo modified starches as new direct compression excipients. I. Tabletting characteristics

This investigation evaluated some new (Preflo) and existing commercially available (Starch 1500, Star Tab) modified starches as direct compression excipients. Preflo corn starches (CH-10, CH-20, CH-30) and Preflo potato starches (P-250, PI-10, PJ-20) were evaluated and compared with respect to their pharmaceutical properties such as particle size, density, flowability, friability, and compression properties. Preflo starches showed a high bulk density and good flowability. Preflo corn starches and Star Tab formed harder tablets than Preflo potato starches and Starch 1500. Data from the Athy-Heckel plots indicated that the Preflo starches are soft materials and, unlike Starch 1500, undergo plastic deformation. Tablets containing acetaminophen were also compressed with the starches and disintegration and dissolution studies were conducted. Starch 1500 tablets disintegrated in 3.5 min, whereas none of the Preflo starch tablets disintegrated in 30 min. While complete acetaminophen release occurred in 25 min from Starch 1500 tablets, the drug dissolution time from Preflo starch tablets varied from 4 to 12 hr, indicating a potential use for some of these starches in solid oral modified-release dosage forms.

p53 and c-myc expression in stage A1 prostatic adenocarcinoma: useful prognostic determinants?

Forty-five stage A1 prostatic adenocarcinomas from patients with a mean age of 65 years were examined for p53 and c-myc expression to determine whether the presence or absence of these proteins could predict tumor behavior. Thirteen (6 of 45) and seventy-three percent (33 of 45) of cases were respectively p53 and c-myc positive. p53 expression was confirmed to the tumor cells, whereas c-myc immunoreactivity was present in both malignant and surrounding hyperplastic prostate. Statistical analysis showed that although p53 and c-myc expression were positively correlated, expression of neither nuclear protein was associated with a significantly worse survival (p53: p = 0.0791 exact two-tailed; c-myc: p = 0.738 exact two-tailed). These results suggest that while both p53 and c-myc may play a role in prostatic carcinogenesis, neither appears to identify patients who may benefit from treatment in stage A disease.

Low prevalence of human papillomavirus types 16 and 18 in cervical adenocarcinoma in situ, invasive adenocarcinoma, and glandular dysplasia by polymerase chain reaction

Using the polymerase chain reaction on paraffin blocks for human papillomavirus (HPV) types 16 and 18, a positive result was seen in three of 20 cases of invasive adenocarcinoma, 15 of 36 cases of adenocarcinoma in-situ, and one of five cases of glandular dysplasia of the uterine cervix. Types 16 and 18 were found with equal frequency. In adenocarcinoma in situ there was no age difference between HPV-positive and or HPV-negative cases. Concomitant squamous dysplasia was slightly more frequent in HPV-positive adenocarcinoma in-situ. HPV positivity rates are lower than most of those previously reported. Possible reasons for this are discussed.

Eye muscle prosthesis

We inserted a silicone rubber elastic band along the course of a paralyzed lateral rectus and of a paralyzed superior oblique to restore alignment and to provide a spring against which the antagonist could pull. The lateral rectus band has been in place for 7 years. It provides alignment and a field of single binocular vision of 20 degrees. The superior oblique band has been in place for 17 months. It provides alignment and single vision over 30 degrees from the primary position except for a restriction in upgaze-adduction to 25 degrees (Brown syndrome) and in downgaze-adduction to 20 degrees. Such engineered elastic bands are a useful addition to current surgical techniques for management of cases of paralysis and restriction.

Polymerase chain reaction and allele-specific oligonucleotides in paternity testing of the deceased

The assignment of paternity when the alleged father has died is now possible by use of a variety of allele-specific oligonucleotides after amplification of genomic DNA by the polymerase chain reaction (PCR). Issues relating to the inheritance of estates may be decided on fact rather than allegation. PCR-based genotyping of DQ alpha haplotypes from paraffin-embedded tissue of the deceased was used to prove non-paternity in the case reported here. Because the child was female, it was also possible to confirm the exclusion by using a second polymorphic site located in the factor VIII gene on the X chromosome.

Length-tension recording system for strabismus surgery

To meet the need for both scientific information and a clinical means for measurement of the mechanical parameters of the most difficult individual strabismus cases we present a technique for directly measuring and plotting the length-tension characteristics of the tissues supporting the eye. Semiconductor strain gauges mounted on the shanks of a custom machined eye forceps and an ultrasonic method of making continuous duction measurements of the eye have proved feasible. When the forceps are interfaced with a dedicated microcomputer, the system provides a permanent, quantitative, length-tension record displayed in real-time. The instrumented length-tension forceps system has provided a noninvasive means for quickly and simply assessing the mechanical underlying determinants of strabismus pathology in the office, the laboratory or in the operating room, and can aid in the planning and immediate intraoperative alteration of strabismus surgery. Under operator coordination, measurements can be made which precisely define the mechanical load which the eye muscles must move. The resulting objectively determined tissue stiffness asymmetries and muscle restrictions limiting ocular motion indicate the purely mechanical contributions to a patient's strabismus. Measurements of active force indicate the magnitudes and patterns of innervation over the entire range of gaze. By comparison of these active force and passive stiffness records, nerve signal imbalances may be quantitatively distinguished from mechanical imbalances in strabismus. It is the detailed interaction of these nonlinear muscle forces and mechanical elements which determines the position of each eye in strabismus and therefore the proper surgical treatment. A brief description of actual use and a few examples of clinical results are included from over 200 human records.

An efficient method for selecting unique-sequence clones from DNA libraries and its application to fluorescent staining of human chromosome 21 using in situ hybridization

This paper describes an efficient procedure for selecting large numbers of unique-sequence or very low repeat-sequence probes from recombinant phage libraries. Probes were selected from the Charon 21A library LL21NS02 (made from DNA from human chromosome 21) in a multistep process in which (1) inserts from LL21NS02 were subcloned into Bluescribe plasmids, (2) plasmids were grown at high density in colonies on nitrocellulose, and (3) plasmids were selected as containing unique-sequence inserts if DNA from the colonies failed to hybridize, at low stringency, to radiolabeled total human DNA. In this manner, 1530 colonies were picked to form the library pBS-U21/1530. About 80% of the recombinants constituting pBS-U21/1530 were shown by Southern analysis to carry inserts that are present in only one copy in haploid genomic human DNA. Approximately 70% of the sequences mapped to human chromosome 21. Fluorescence in situ hybridization with DNA from pBS-U21/1530 allowed specific, intense staining of the number 21 chromosomes in metaphase spreads made from human lymphocytes.

Combined cataract extraction and epikeratophakia in children

Nineteen children between the ages of 2 1/2 and 6 1/2 years who had cataracts not associated with trauma and who were judged to be poor candidates for contact lens wear underwent combined cataract extraction and epikeratophakia, followed by intensive amblyopia therapy. Follow-up ranged from 6 months to 7 years. In these monocularly aphakic children, three (16%) of the original 19 procedures failed and the tissue lenses were removed; two of these were repeated successfully. The success rate for the surgery was 86% (18/21) and 95% (18/19) for the patients. Postoperative visual acuity of 20/50 or better was achieved in six (33%) of the 18 patients with successful surgery. Another 11 (61%) achieved between 20/60 and 20/200. Postoperative astigmatism ranged between 0 and 4 diopters, with an average of 1.7 diopters. The results demonstrate that epikeratophakia can be successfully combined with cataract extraction in children with visually significant non-traumatic cataracts and that the majority of such children demonstrate an improvement in visual acuity.

Human chromosome-specific DNA libraries: construction and purity analysis

We report the construction of eight human chromosome-specific DNA libraries. Metaphase chromosomes were purified by flow-sorting, and the extracted DNA was cleaved with HindIII before cloning into lamba Charon 21A. There is now a complete digest HindIII library containing greater than five chromosome equivalents for each human chromosome. These are available to the scientific community through the American Type Culture Collection in Rockville, MD. The amount of hamster DNA in libraries in which the chromosome was sorted from human x hamster hybrid cells was estimated by species-specific hybridization. It ranged from 5% to 39%. The sorted chromosomes were examined by fluorescence in situ hybridization with species-specific DNA, and the main source of the hamster DNA contamination was found to be intact hamster chromosomes. In addition, we examined a chromosome 21 library, LL21NS02, for clones that fail to grow on the rec+ host LE392. Less than 0.6% of the recombinant phage exhibited the rec+-inhibited phenotype.

Recent progress with the DNA repair mutants of Chinese hamster ovary cells

Repair-deficient mutants of Chinese hamster ovary (CHO) cells are being used to identify human genes that correct the repair defects and to study mechanisms of DNA repair and mutagenesis. Five independent tertiary DNA transformants were obtained from the EM9 mutant, which is noted for its very high sister-chromatid exchange frequencies. In these clones a human DNA sequence was identified that correlated with the resistance of the cells to chlorodeoxyuridine (CldUrd). After EcoRI digestion, Southern transfer, and hybridization of transformant DNAs with the BLUR-8 Alu family sequence, a common fragment of 25-30 kilobases (kb) was present. Since the DNA molecules used to produce these transformants were sheared to less than 50 kb in size, the correcting gene should be small enough to clone in a cosmid vector. Using drug-resistance markers to select for hybrids after fusion, we have done complementation experiments with ultraviolet light (u.v.)-sensitive mutants and have identified a sixth complementation group, line UV61. Additionally, CHO mutants UV27-1 and MMC-2, isolated in other laboratories, were found to belong to UV group 3, which is represented by line UV24. To study the behaviour of transfected DNA molecules in repair-deficient cells, we treated plasmid pSV2gpt with either u.v. radiation or cis-diamminedichloroplatinum(II) (cis-DDP) and introduced the damaged DNA into normal CHO cells (AA8) and mutants UV4 and UV5. Unrepaired damage to the plasmid was indicated by loss of colony-forming ability of the transfected cells in selective medium containing mycophenolic acid. With u.v. damage, the differential survival of the cell lines was similar to that seen when whole cells are treated with u.v. However, with cis-DDP damage, mutant UV4 did not exhibit the extreme hypersensitivity (50-fold) that occurs when cells are treated. This result suggests that UV4 cells may be able to repair cross-links in transfected DNA.

Extraocular muscle forces in normal human subjects

Actively developed horizontal muscle forces and tissue stiffnesses were measured in 29 normal orthophoric volunteer subjects (18 to 33 years old) by means of noninvasive length-tension forceps. Mean active fixation force developed at 50 deg extreme gaze was 26% greater for the medial rectus (74.8 gm) than for the lateral rectus (59.1 gm). The variation of maximum active force among individuals was 2:1 (48 to 103 gm). These muscles developed up to 25% of their maximum active force out of their field of action. Active (counter) hysteresis force differences of over 10 gm were measured between nasal and temporal gaze directions. This study suggests that a muscle which develops a maximum active force of less than 45 gm would be suspect as paretic. Variations from the normal pattern of reciprocal innervation, reflected in the graded active force of individual muscle contraction, may help in understanding some types of oculomotor pathology. The mean tissue stiffness-restraining movement of the globe in the nasal direction (1.05 gm/deg) is 11% greater than in the temporal direction (0.94 gm/deg). This is consistent with a stronger medial rectus balanced by a greater load. Variation of stiffness of 2:1 was observed among individuals; 0.8 to 1.7 gm/deg pulling nasally and 0.77 to 1.2 gm/deg temporally. Passive hysteresis and viscous force differences of over 10 gm were observed between the passive forced pull and normal spring-return of the eye. Large stiffnesses may be normal if balanced by large active forces. Abrupt changes of the length-tension curve indicate the magnitude and location of restrictions.

Microbial transformations and 13C-NMR analysis of colchicine

Several microorganisms were screened for their ability to biotransform colchicine, and two were selected for preparative scale fermentations. Streptomyces spectabilis and Streptomyces griseus both produced O2-demethylcolchicine and O3-demethylcolchicine but in different amounts. The 13C-NMR assignments of colchicine, O10-demethylcolchicine, and trimethylcolchicinic acid are reported and were used to help identify the structures of the metabolites.

Muscle tension during unrestrained human eye movements

1. Tensions in the horizontal rectus muscles have simultaneously and continuously been recorded during unrestricted eye movements in four strabismus patients, using force transducers small enough to be implanted in series between the tendons and their points of insertion on the globe. 2. Levels of tension required to maintain fixation at each position of gaze vary from a minimum of 8-12 g approximately 15 degrees outside of muscle's field of action to a maximum of around 40 g at extreme gaze within the muscle's field of action. When tension is plotted as a function of eye position, the static locus of fixation tension levels exhibits a parabolic relationship. 3. Tensions recorded during smooth following movements parallel or slightly exceed those of fixation. 4. At the onset of a saccade, tension in the agonist rises isometrically, then, as the eye moves, tension levels parallel those of fixation but with an isotonic increment of 15-25 g. At the end of the saccadic movement, tension falls essentially isometrically to the new fixation level. 5. Tension in the antagonist reveals an unexpected peak at the onset of a saccade. 6. For saccadic movements tension increments of 15-25 g above the fixation levels suffice to move the eye rapidly to a new position of gaze, regardless of the duration of the saccade and the location of the new fixation point. 7. Maximum and minimum levels of tension during normal fixation, following and saccadic movements, plotted as a function of eye position, form an operational envelope which defines the limits of muscle forces during normal eye movements. The lowest level of this envelope is the parabolic static locus of fixation tensions.

Evoked pressure responses in the rabbit eye

In the rabbit, a sensory stimulus of low intensity evokes a characteristic transient intraocular rise in pressure with an amplitude as great as 10 millimeters of mercury. This alpha- adrenergically mediated phenomenon occurs concomitantly with a general arousal response and appears to be caused by contraction of the orbital smooth muscle of Müller.