Ethnicity and attitudes towards life sustaining technology

The ethical and legal implications of decisions to withhold and withdraw life support have been widely debated. Making end-of-life decisions is never easy, and when the cultural background of doctor and patient differ, communication about these issues may become even more difficult. In this study, we examined the attitudes of people aged 65 and older from different ethnic groups toward foregoing life support. To this end, we conducted a survey of 200 respondents from each of four ethnic groups: European-American, African-American, Korean-American and Mexican-American (800 total), followed by in-depth ethnographic interviews with 80 respondents. European-Americans were the least likely to both accept and want life-support (p < 0.001). Mexican-Americans were generally more positive about the use of life-support and were more likely to personally want such treatments (p < 0.001). Ethnographic interviews revealed that this was due to their belief that life-support would not be suggested if a case was truly hopeless. Compared to European-Americans, Korean-Americans were very positive regarding life-support (RR = 6.7, p < 0.0001); however, they did not want such technology personally (RR = 1.2, p = 0.45). Ethnographic interviews revealed that the decision of life support would be made by their family. Compared to European-Americans, African-Americans felt that it was generally acceptable to withhold or withdraw life-support (RR = 1.6, p = 0.06), but were the most likely to want to be kept alive on life-support (RR = 2.1, p = 0.002). Ethnographic interviews documented a deep distrust towards the health care system and a fear that health care was based on one's ability to pay. We concluded that (a) ethnicity is strongly related to attitudes toward and personal wishes for the use of life support in the event of coma or terminal illness, and (b) this relationship was complex and in some cases, contradictory.

Limiting dynamics of high-frequency electromechanical transduction of outer hair cells

High-frequency resolution is one of the salient features of peripheral sound processing in the mammalian cochlea. The sensitivity originates in the active amplification of the travelling wave on the basilar membrane by the outer hair cells (OHCs), where electrically induced mechanical action of the OHC on a cycle-by-cycle basis is believed to be the crucial component. However, it is still unclear if this electromechanical action is sufficiently fast and can produce enough force to enhance mechanical tuning up to the highest frequencies perceived by mammals. Here we show that isolated OHCs in the microchamber configuration are able to overcome fluid forces with almost constant displacement amplitude and phase up to frequencies well above their place-frequency on the basilar membrane. The high-frequency limit of the electromotility, defined as the frequency at which the amplitude drops by 3 dB from its asymptotic low-frequency value, is inversely dependent on cell length. The frequency limit is at least 79 kHz. For frequencies up to 100 kHz, the electromotile response was specified by an overdamped (Q = 0.42) second-order resonant system. This finding suggests that the limiting factor for frequencies up to 100 kHz is not the speed of the motor but damping and inertia. The isometric force produced by the OHC was constant at least up to 50 kHz, with amplitudes as high as 53 pN/mV being observed. We conclude that the electromechanical transduction process of OHCs possesses the necessary high-frequency properties to enable amplification of the travelling wave over the entire hearing range.

Partial functional deficiency of E160D flap endonuclease-1 mutant in vitro and in vivo is due to defective cleavage of DNA substrates

To assess the roles of the active site residues Glu160 and Asp181 of human FEN-1 nuclease in binding and catalysis of the flap DNA substrate and in vivo biological processes of DNA damage and repair, five different amino acids were replaced at each site through site-directed mutagenesis of the FEN-1 gene. The mutants were then expressed in Escherichia coli and purified using a His-tag. Even though the mutants bind to the flap DNA to different degrees, most of the mutants lost flap nuclease activity with the exception of an E160D mutant. This mutant retained wild type-like binding ability, specificity, and partial catalytic activity. Detailed steady state and pre-steady state kinetic analysis revealed that the functional deficiency of this mutant was due to retardation of the endonucleolytic cleavage. When the mutant enzyme E160D was expressed in yeast, it partially complements the biological functions of the homologous yeast gene, RAD27, and reverses the hyper-temperature lethality and hypersensitivity to methyl methanesulfonate, in a manner corresponding to the in vitro activity.

A discourse of relationships in bioethics: patient autonomy and end-of-life decision making among elderly Korean Americans

A two-year, multidisciplinary study (N = 800) was conducted on attitudes about end-of-life decision making among elderly individuals in four ethnic groups (African American, European American, Korean American, and Mexican American). On a quantitative survey, Korean Americans reported negative attitudes about the use of life-sustaining technology for themselves but positive attitudes about its use in general. This article reports on an interview with a 79-year-old typical Korean American respondent to explain the contradiction in the survey data. Expectations among elderly Korean Americans include protecting family members with a life-threatening illness from being informed of their diagnosis and prognosis, and doing everything to keep them alive. Two conclusions, one substantive and the other methodological, are drawn: First, the bioethics discourse on individual rights (patient autonomy) is insufficient to explain the preferences of many Korean Americans and must be supplemented with a discourse on relationships. Second, the rigorous use of qualitative, narrative methods clarifies quantitative data and should not be dismissed as "anecdotal."

Newly discovered archaebacterial flap endonucleases show a structure-specific mechanism for DNA substrate binding and catalysis resembling human flap endonuclease-1

Mammalian flap endonuclease-1 (FEN-1) is a structure-specific metalloenzyme that acts in processing of both the Okazaki fragments during lagging strand DNA synthesis and flap intermediates during DNA damage repair. We identified and cloned three open reading frames encoding a flap endonuclease from Archaeglobus fulgidus, Methanococcus jannaschii, and Pyrococcus furiosus, respectively. The deduced FEN-1 protein sequences share approximately 75% similarity with the human FEN-1 nuclease in the conserved nuclease domains, and extensive biochemical experiments indicate that the substrate specificities and catalytic activities of these enzymes have overall similarities with those of the human enzyme. Thus, FEN-1 enzymes and likely reaction mechanisms are conserved across the eukaryotic and archaeal kingdoms. Detailed comparative analysis, however, reveals subtle differences among these four enzymes including distinctive substrate specificity, tolerance of the archaebacterial enzymes for acidic pHs and elevated temperatures, and variations in the metal-ion dependence of substrate cleavage. Although the archaebacterial enzymes were inactive at temperatures below 30 degreesC, DNA binding occurred at temperatures as low as 4 degreesC and with or without metal ions. Thus, these archaeal enzymes may provide a means to dissect the specific binding and catalytic mechanisms of the entire FEN-1 family of structure-specific nucleases.

Granulomatous hypophysitis caused by a ruptured intrasellar Rathke's cleft cyst: report of a case and review of the literature

OBJECTIVE AND IMPORTANCE

Ruptured Rathke's cleft cyst is a rare cause of giant cell granulomatous hypophysitis. Chronic inflammatory reaction is caused by extravased cyst content into the adjacent gland. We provide a demonstration that mucins produced by cells lining the cyst wall caused the granulomatous giant cell reaction.

CLINICAL PRESENTATION

A 37-year-old nonpregnant woman presented with a 3-year-history of headache and amenorrhea. She had experienced normal sexual maturation, and her medical history was unremarkable. Radiologically, the lesion appeared as an intrasellar mass with a cystic component indistinguishable from a pituitary adenoma with cystic degeneration.

TECHNIQUE

The patient underwent a transsphenoidal approach. Because no demarcation between normal and affected tissue was evident at surgery, the lesion and residual pituitary were radically removed. Tissue was studied using routine hematoxylin and eosin and histochemical stainings for mucins and immunocytochemical techniques.

CONCLUSION

This study demonstrates that mucins that had spilled out from the cyst caused the granulomatous reaction. Using computed tomography, magnetic resonance imaging, and gross inspection, distinction between granulomatous hypophysitis and pituitary adenoma was virtually impossible. Nevertheless, a granulomatous reaction of the pituitary gland should be suspected in a case of a sellar mass having a cystic area. In such cases, intraoperatory diagnosis on frozen sections is mandatory because adoption of a conservative treatment allows preservation of the gland.

Transient regression of an intracranial germ cell tumour after intravenous steroid administration: a case report

Magnetic resonance imaging showed transient regression of the lesion after intravenous steroid administration in a patient with intracranial multifocal germ cell tumour. Prominent lymphocyte infiltration of the tumour was seen at histological examination and presumably accounts for the regression. Germ cell tumour must be included in the differential diagnosis of intracranial mass lesions sensitive to steroids.

[Cytogenetic analysis of hypophyseal adenoma. Study of 9 cases and review of the literature]

INTRODUCTION

To the best of our knowledge, no specific chromosomal abnormalities have been found in the literature in pituitary adenomas. In the present study, we investigated 9 cases of pituitary adenoma and reviewed the current literature.

MATERIALS AND METHODS

Nine cases of pituitary adenoma have been studied with immunohistochemistry and cytogenetic using short-term cultures.

RESULTS

All tumors had a normal karyotype. Three cases were clinically non-secreting adenomas, three cases produced prolactin, two showed growth hormone production and one thyroid-stimulating hormone. One of the cases showed dural invasion.

CONCLUSIONS

We compared our results with those published in the current literature. It appears that pituitary adenomas do not have specific numerical and structural abnormalities and mostly show a normal karyotype.

Intermediate follow up of the TEKNA bileaflet valve

BACKGROUND AND AIM OF THE STUDY

The study aim was to collect intermediate clinical data on the TEKNA bileaflet valve.

METHODS

This nine-center clinical study involved 884 patients implanted between June 1990 and October 1993. The population consisted of 522 (59.0%) males and 362 (41.0%) females. Mean age at implant was 59.1 +/- 11.8 years (range: 14.7 to 88.4 years). Indication for valve replacement was dependent on the position: stenosis was the predominant reason in the aortic position; regurgitation was more pronounced for the mitral position. A total of 261 (29.5%) patients underwent concomitant procedures. Mean follow up is 2.7 +/- 1.2 years; total follow up is 2386.1 patient-years (pt-yr).

RESULTS

Total operative (< or = 30 days postoperative) mortality rate was 3.7%; seven patients (0.8%) died due to valve-related causes. Total postoperative (> 30 days postoperative) mortality rate was 2.5%/pt-yr and included a valve-related mortality rate of 1.1%/pt-yr. The following valve-related complication rates (%/pt-yr) were reported for the long-term postoperative period: thromboembolism 0.6; valve thrombosis 0.3; bleeding events 1.5; non-structural deterioration 0.6; and endocarditis 0.4. No structural valve deterioration was reported. Actuarial freedom at four years was: overall survival rate 86.9 +/- 1.4%; valve-related survival rate 94.7 +/- 1.0%; freedom from thromboembolism 96.8 +/- 0.9%; valve thrombosis 99.3 +/- 0.3%; endocarditis 98.5 +/- 0.5%; bleeding events 94.3 +/- 1.0%; and non-structural deterioration 98.2 +/- 0.6%.

CONCLUSIONS

The data indicate that observed mortality is due mainly to non-valve-related disorders. Risk of thromboembolic and bleeding events was low (0.9%/pt-yr and 1.5%/pt-yr, respectively). We conclude that this valve is safe and efficacious for use.

Unexpected association between reproductive longevity and blood magnesium levels in a new model of selected mouse strains

Two recently described mouse strains, with high (MGH) and low (MGL) blood magnesium (Mg) levels were obtained by selection over 19 generations. Both strains exhibit strong differences for characteristics generally known to be related to blood Mg levels, such as increased stress sensitivity and stress-induced aggressivity in MGL mice. In contrast, while experimental Mg deficiency due to low oral Mg intake has been shown to shorten life span and lower reproductive ability, reproductive longevity was longer in the MGL than in the MGH strain. Interestingly, the life spans of the two strains are very similar. Although this character could have been fixed in the strains by chance, with no relationship to the blood Mg level, the possibility of a causal link with the selection cannot be ruled out and is discussed. Regardless of the mechanisms at stake, the MGH and MGL strains appear to constitute a new model for the study of the relationships between reproductive longevity and blood Mg levels.

Friedreich's ataxia. Revision of the phenotype according to molecular genetics

Friedreich's ataxia is an autosomal recessively inherited neurodegenerative disorder caused by expansions of an unstable GAA trinucleotide repeat in the STM7/X25 gene on chromosome 9q. We studied the (GAA)n polymorphism in 178 healthy controls and 102 patients with idiopathic ataxia. The repeat size ranged from 7 to 29 (GAA)n motifs on normal chromosomes and from 66 to 1360 trinucleotide repetitions in Friedreich's ataxia patients. Meiotic instability of expanded alleles was observed without significant differences in maternal and paternal transmissions. Thirty-six of 102 patients were typed homozygous for expanded (GAA)n alleles. Twenty-seven of these presented with the typical Friedreich's ataxia symptoms and nine patients with an atypical Friedreich's ataxia phenotype. Before molecular genetic diagnosis had been performed seven of these patients had been classified as early onset cerebellar ataxia and two as idiopathic sporadic cerebellar ataxia of late onset. In contrast, in one family with typical Friedreich's ataxia phenotype we did not find an expanded allele; this suggests that there can be either point mutations in the X25 gene on both chromosomes or locus heterogeneity in Friedreich's ataxia. The phenotypic spectrum of Friedreich's ataxia is much broader than considered before. Early onset, areflexia, extensor plantar responses and reduced vibration sense should no longer be considered essential diagnostic criteria of Friedreich's ataxia. In comparison with the non-Friedreich's ataxia group hypertrophic cardiomyopathy seems to be the only symptom specific for Friedreich's ataxia. However, it is not obligatory. The phenotype is significantly influenced by the number of GAA repeats with close genotype-phenotype relationships when the smaller of the two alleles is considered. Repeat length correlated inversely with age at onset, onset of dysarthria and progression rate. In conclusion, molecular genetic analysis appears mandatory for the diagnosis and genetic counselling of Friedreich's ataxia. The molecular genetic test should be applied not only to patients with typical Friedreich's ataxia phenotype but also in all cases of idiopathic autosomal recessive or sporadic ataxia.

Research assessment of the clinical utility of the Rorschach

A summary of prior research on the clinical use of the Rorschach Ink Blots is presented.

Acoustical and electrical biasing of the cochlea partition. Effects on the acoustic two tone distortions f2-f1 and 2f1-f2

Low frequency acoustical biasing of the cochlear partition with 5 Hz tones produces phase correlated changes of the acoustic two-tone distortions 2f1-f2 and f2-f1. Pronounced changes of f2-f1 and only small changes of 2f1-f2 for lower bias tone levels indicate that there is a close relation between changes in the difference tone f2-f1 and changes in the operating point of the cochlear amplifier (Frank and Kössl, 1996). To further investigate this relationship, the cochlear partition was additionally biased by current injection into the scala media of the gerbil. The injection of low frequency (5 Hz) AC currents (max. 1.3 microA) has a similar effect to that caused by low frequency tones in that both produce phase correlated changes of the two distortions (so-called biasing patterns), with stronger effects on f2-f1. For bias tone levels of about 105 dB SPL and current values of 1.3 microA, the effects are approximately of the same size. A change in the f2-f1 biasing pattern that can be found for increasing bias tone levels can also be seen for increasing primary levels. Changing the setpoint of the cochlear amplifier through the injection of DC current into the scala media during acoustical biasing of the cochlear partition produces the same changes of f2-f1 biasing patterns as increasing the primary levels. This indicates that the operating point of the outer hair cells that respond to the primary tones is not only influenced by low frequency biasing stimuli but also by shifts with increasing primary levels.

The alpha-amylase from the yellow meal worm: complete primary structure, crystallization and preliminary X-ray analysis

The alpha-amylase from Tenebrio molitor larvae (TMA) was purified from a crude larval extract. After removal of the N-terminal pyroglutamate residue and identification of the following 17 residues by Edman sequencing, the cDNA of mature TMA was cloned from larval mRNA. The encoded enzyme consists of 471 amino acid residues and has 57-79% sequence identity to other insect alpha-amylases and also shows high homology to the mammalian enzymes. TMA was crystallized in form of well-ordered orthorhombic crystals of space group P2(1)2(1)2(1) diffracting beyond 1.6 A resolution with unit cell dimensions of a = 51.24 A, b = 93.46 A, c = 96.95 A. TMA may serve as model system for the future analysis of interactions between insect alpha-amylase and proteinaceous plant inhibitors on the molecular level.

Differential stability of the (GAA)n tract in the Friedreich ataxia (STM7) gene

Friedreich ataxia (FA) is an autosomal recessive, neurodegenerative disorder characterized by polypurine trinucleotide expansion. The (GAA)n motif is located in intron 18 of the STM7 gene (previously considered as intron 1 of the X25 gene) on chromosome 9q13. We studied the distribution profile of the polymorphic (GAA)n repetitive tract in 178 healthy individuals. The number of repeats of the trinucleotide block ranged from 7 to 29. In three individuals there were more than 29 repetitions of the GAA motif. While two of the individuals would be diagnosed as carriers of the FA mutation (GAA size > 90), the status of the third person, with a (GAA)58 tract, appears less clear at present. Thus an FA carrier rate of 1/60 to 1/90 can be assumed for the German population. In addition an intermediate-sized allele, (GAA)38 was identified in a mother with two affected children. The (GAA)38 allele appears to be expanded during transmission to at least (GAA)66 and (GAA) > 400 in her two FA-affected offspring. Therefore the shortest known STM7 allele conferring FA is (GAA)66. These novel facts have to be considered for differential diagnosis and definition of the FA carrier state.

Remote memory in patients with acute brain injuries

Remote memory was investigated in an unselected sample of 26 patients with either unilateral tumours in the temporal lobes or traumatic brain injuries. Six patients underwent excisions within the left temporal lobe, and nine patients were operated on within the right temporal lobe. In both groups, patients with excisions including and sparing the hippocampal formation were studied. Their performance was compared to that of 11 patients with moderate to severe head trauma and to a normative sample of 214 healthy controls. Remote memory was assessed using a famous events test with items of extremely low salience that had been proven to be of low difficulty for those old enough at the time of the event's actuality. The results show severely disturbed retrograde memory functions in the left temporal tumour group. These patients achieved similar scores to patients with severe traumatic brain injury. Right hemispheric patients showed a pattern of results comparable to that of healthy controls. The strongest effects were in the free recall part of the test. In most of the patients, no graded memory loss was observable. No consistent association to recent memory function could be identified. Since most of the remote memory test items used denoted famous names which were cued by rich semantic information, the type of deficit seen may be best understood in terms of a specific dysfunction of the semantic stores containing information about famous proper names.

Jewish spirituality through actions in time: daily occupations of young Orthodox Jewish couples in Los Angeles

Ethnographic methods were used to study daily occupations and weekly routines of four young Orthodox Jewish couples living in Los Angeles. Data from interviews and participant observation demonstrate the importance to the couples of fulfilling God's commandments [Hebrew, mitzvot], which organize and sanctify the otherwise mundane activities of daily living, such as eating, bathing sleeping, and rising. The article focuses on the couples' experiences in (a) observing the Sabbath, (b) studying and praying, and (c) keeping a kosher home. Orthodox Jewish ritual, practice, and spirituality are time bound and action oriented. Occupational therapists can benefit from understanding how Orthodox Jews invest and experience spiritual meaning in seemingly mundane occupations and routines.

The acoustic two-tone distortions 2f1-f2 and f2-f1 and their possible relation to changes in the operating point of the cochlear amplifier

Acoustic two-tone distortions are generated during non-linear mechanical amplification in the cochlea. Generation of the cubic distortion 2f1-f2 depends on asymmetric components of a non-linear transfer function whereas the difference tone f2-f1 relies on symmetric components. Therefore, a change of the operating point and hence the symmetry of the cochlear amplifier could be strongly reflected in the level of the f2-f1 distortion. To test this hypothesis, low-frequency tones (5 Hz) were used to bias the position of the cochlear partition in the gerbil. Phase-correlated changes of f2-f1 occurred at bias tone levels where there were almost no effects on 2f1-f2. Higher levels of the bias tone induced pronounced changes of both distortions. These results are qualitatively in good agreement with the results of a simulation in which the operating point of a Boltzman function was shifted. This function is similar to those used to describe outer hair cell (OHC) transduction. To influence OHC motility, salicylate was injected. It caused a decrease of the 2f1-f2 level and an increase in the level of f2-f1. Such reciprocal changes of both distortions, again, can be interpreted in terms of a shift of the operating point of the cochlear amplifier along a non-linear transfer characteristic. To directly influence the cochlear amplifier, DC current was injected into the scala media. Large negative currents (> -2 microA) caused a pronounced decrease of 2f1-f2 (> 15 dB) and positive currents had more complex effects with increasing and/or decreasing 2f1-f2 distortion level. The effects were time and primary level dependent. Changes of f2-f1 for DC currents > magnitude of mu 2A were in most cases larger compared to 2f1-f2 and reversed for certain primary levels. The current effects probably result from a combination of changing the endocochlear potential and shifting the operating point along a non-linear transfer function.

The antenna complexes of the purple non-sulfur photosynthetic bacterium Rhodocyclus tenuis. Structural and spectral characterization

The photoreceptor complex (B885-RC) and the peripheral antenna complex (B800-860) were isolated from photosynthetic membranes of the purple non-sulfur bacterium Rhodocyclus tenuis DSM 109 using a detergent combination of Deriphate-160 and octyl glucoside and subsequent linear sucrose gradient centrifugation. The two complexes were characterized by room-temperature absorption, circular dichroism and fluorescence spectroscopy. The B800-860 complex has a more red-shifted B860 absorbance band. The alpha,beta-polypeptides were purified with a reverse-phase HPLC system and resolved at a ratio of 1:1 in the B800-860 complex and at an overall ratio of 1:1 for the B885-RC complex. The complete amino acid sequences of the alpha and beta polypeptides of the B800-860 and B885-RC complexes were determined by micro-sequencing analysis and mass spectrometry. The B800-860-alpha polypeptide possesses an identical N-terminal domain (the first 15 residues) to Rhodobacter sphaeroides B800-850-alpha polypeptide. The central hydrophobic and C-terminal domains of the B800-860-alpha,beta polypeptides show a number of B870/880-like structural elements in which, of special interest, is the WWSEF cluster in the C-terminal domain of the B800-860-alpha polypeptide which is very similar to the WWEF cluster in the same region of Rhodopseudomonas viridis B1015-alpha polypeptide. The more red-shifted absorption characteristic of the 860-nm bacteriochlorophylls could most probably be related to the B870/880-like polypeptide features in the central hydrophobic domains and the C-terminal domains of the B800-860-alpha,beta polypeptides. The hydropathy plot of the B800-860-alpha polypeptide exhibits an extended C-terminal hydrophobic segment indicative of a second membrane-contacting domain, which has not been found in the antenna polypeptides of the purple bacteria with intracytoplasmic membranes. Further sequence analysis revealed the existence of multiple forms of the B885-alpha,beta polypeptides, the B885-alpha 1,alpha 2 polypeptides, and the B885-beta 1,beta 2 polypeptides. The B885-Alpha 2 polypeptide shows an identical sequence to the B885-alpha 1 polypeptide, but it is 12 amino acid residues shorter than the B885-alpha 1 polypeptide at the C-terminal. The two species of the B885-beta polypeptides were identified as an identical sequence with only one amino acid residue variation at sequence position 34, where the B885-beta 1 has a valine residue and the B885-beta 2 polypeptide an isoleucine residue. The possible correlation between the intensity of the near-infrared circular dichroic signal and the specific structural features of the alpha and beta core antenna polypeptides is also discussed.

Life histories in occupational therapy clinical practice

This article defines and compares several narrative methods used to describe and interpret patients' lives. The biographical methods presented are case histories, life-charts, life histories, life stories, assisted autobiography, hermeneutic case reconstruction, therapeutic employment, volitional narratives, and occupational storytelling and story making. Emphasis is placed the clinician as a collaborator and interpreter of the patient's life through ongoing interactions and dialogue.

Pseudogenes in ribonuclease evolution: a source of new biomacromolecular function?

Bovine seminal ribonuclease (RNase) diverged from pancreatic RNase after a gene duplication ca. 35 million years ago. Members of the seminal RNase gene family evidently remained as unexpressed pseudogene for much of its evolutionary history. Between 5 and 10 million years ago, however, after the divergence of kudu but before the divergence of ox, evidence suggests that the pseudogene was repaired and expressed. Intriguingly, detailed analysis of the sequences suggests that the repair may have involved gene conversion, transfer of information from the pancreatic gene to the RNase pseudogene. Further, the ratio of non-silent to silent substitutions suggests that the pancreatic RNases are divergently evolving under functional constraints, the seminal RNase pseudogenes are diverging under no functional constraints, while the genes expressed in the seminal plasma are evolving extremely rapidly in their amino acid sequences, as if to fulfil a new physiological role.

Isolation, characterization and electron microscopy analysis of a hemidiscoidal phycobilisome type from the cyanobacterium Anabaena sp. PCC 7120

In this work we present the characterization of a hemidiscoidal phycobilisome type of the heterocyst-forming cyanobacterium Anabaena sp. PCC 7120. The phycobilisome of this organism contains allophycocyanin, phycocyanin and phycoerythrocyanin, similar to the closely related thermophilic cyanobacterium Mastigocladus laminosus. Intact phycobilisomes exhibit an absorption maximum at 619 nm and two fluorescence maxima at 664 nm and 680 nm, corroborating the presence of a complete energy pathyway along the antenna. Upon dissociation, the phycobiliproteins were released from the phycobilisome. One phycoerythrocyanin, one phycocyanin and three allophycocyanin complexes were isolated by ion-exchange chromatography and characterized by absorption and fluorescence spectroscopy and by SDS/PAGE. The amino-terminal sequences of the polypeptides belonging to the phycoerythrocyanin and phycocyanin families were identical with the derived sequences of their corresponding genes. Partial amino-terminal sequences of the polypeptides belonging to the allophycocyanin family are presented here. Our results show that the phycobiliproteins and linker polypeptides from Anabaena sp. PCC 7120 are similar to the phycobilisome components characterized in other cyanobacteria. The phycobilisome of Anabaena sp. PCC 7120 was extensively analyzed by electron microscopy. It differs from the common hemidiscoidal tricylindrical, six-rod phycobilisome type by a core domain consisting of five core cylinders surrounded by up to eight rods radiating in a hemidiscoidal manner. One rod is linked to each basal core cylinder, whereas the remaining core cylinders bind two rods each. On the basis of the data presented in this work, a revised model for the hemidiscoidal pentacylindrical phycobilisome of Anabaena sp. PCC 7120, M. laminosus and Anabaena variabilis is proposed. This model accounts more accurately for the 'grape' pattern typically exhibited by these phycobilisomes in electron micrographs.

Acoustic distortion products from the cochlea of the blind African mole rat, Cryptomys spec

The measurement of distortion-product otoacoustic emissions is a noninvasive method that can be used for assessing the sensitivity and the frequency tuning of nonlinear cochlear mechanics. During stimulation with two pure tones f1 and f2, the acoustic 2f1-f2 distortion was recorded in the ear canal of Cryptomys spec. to study specializations in cochlear mechanics that could be associated with the presence of a frequency expanded cochlear region between 0.8-1 kHz. In addition, a distortion threshold curve was obtained which describes relative threshold of nonlinear cochlear mechanics. Sensitive distortion thresholds could be measured for stimulus frequencies between 0.4 to 18 kHz with a broad minimum between 0.75 to 2.5 kHz. The distortion threshold curve extends to higher frequencies than previous neuronal data indicated. As a measure of mechanical tuning sharpness in the cochlea, suppression tuning curves of 2f1-f2 were recorded. The tuning curves reflected the typical mammalian pattern with shallow low frequency and steep high frequency slopes. Their tuning sharpness was poor with Q10dB values between 0.3 and 1.88. In the range of the frequency expanded region, the Q10dB values were below 0.5. This finding emphasizes that the presence of frequency expansion does not necessarily lead to enhanced mechanical tuning in the cochlea and one has to consider if in certain bat species with cochlear frequency expansion and particularly sharp cochlear tuning, the two phenomena may not be interlinked.

Life domains and adaptive strategies of a group of low-income, well older adults

Older adults are at increased risk for a variety of physical and functional limitations that threaten their ability to lead independent and fulfilling lives. Consequently, they stand to benefit from personalized strategies of adaptation that enable them to achieve successful outcomes in their daily activities and desired goals. In the current investigation, a qualitative descriptive methodology was used to document the perceived life domains of importance and associated strategies of adaptation of 29 residents of Angelus Plaza, a federally subsidized apartment complex in downtown Los Angeles for low-income, well older adults. On the basis of interview data, 10 life domains were identified, and within each domain, a typology of adaptive strategies was derived. The domains were activities of daily living (ADL), adaptation to a multicultural environment, free time usage, grave illness and death-spirituality, health maintenance, mobility maintenance, personal finances, personal safety, psychological well-being and happiness, and relationships with others. Although the typology should not be generalized to a geriatric population, therapists may wish to refer to it to gain a sense of the extent to which certain adaptive strategies may be applicable to the lives of particular older adults to whom they deliver services. The teaching of these adaptive strategies could then be incorporated into an individualized treatment plan. The typology also provides a broad picture of the kinds of adaptive strategies used by the older adults as a way of coping and adapting to their setting. Although some of the domains do not differ from those typically addressed in occupational therapy textbooks on geriatric care (e.g., ADL, health maintenance), others seem uniquely tailored to the specifics of the Angelus Plaza context (e.g., personal safety). Finally, certain domains emerged that may be highly relevant to older adults in most settings but are not typically the focus of occupational therapy programs (e.g., grave illness and death-spirituality, relationships with others). The emergence of these domains from our data suggests that therapists may wish to consider them more in treatment if they are convinced that they possess local relevance.