Neurotrophic factor intervention restores auditory function in deafened animals

A primary cause of deafness is damage of receptor cells in the inner ear. Clinically, it has been demonstrated that effective functionality can be provided by electrical stimulation of the auditory nerve, thus bypassing damaged receptor cells. However, subsequent to sensory cell loss there is a secondary degeneration of the afferent nerve fibers, resulting in reduced effectiveness of such cochlear prostheses. The effects of neurotrophic factors were tested in a guinea pig cochlear prosthesis model. After chemical deafening to mimic the clinical situation, the neurotrophic factors brain-derived neurotrophic factor and an analogue of ciliary neurotrophic factor were infused directly into the cochlea of the inner ear for 26 days by using an osmotic pump system. An electrode introduced into the cochlea was used to elicit auditory responses just as in patients implanted with cochlear prostheses. Intervention with brain-derived neurotrophic factor and the ciliary neurotrophic factor analogue not only increased the survival of auditory spiral ganglion neurons, but significantly enhanced the functional responsiveness of the auditory system as measured by using electrically evoked auditory brainstem responses. This demonstration that neurotrophin intervention enhances threshold sensitivity within the auditory system will have great clinical importance for the treatment of deaf patients with cochlear prostheses. The findings have direct implications for the enhancement of responsiveness in deafferented peripheral nerves.     

Recovery concept in a Norwegian setting to be examined by the assertive community treatment model and mixed methods

Recovery is a crucial concept in the mental health field. The research of recovery is split into the categories of personal, social and clinical recovery. The purpose of this study was to explore the fragmented concept of recovery in light of assertive community treatment (ACT) in Norway. The study has a mixed methods design with a pragmatic approach. The Questionnaire about the Process of Recovery and open‐ended questions posed to 70 participants from 12 ACT teams in Norway, gathered by the “Users interview users” method, are combined with interviews or focus groups with eight of these participants. Surprisingly those under a community treatment order (CTO) report the highest degree of personal recovery. The qualitative material shows that the service users interpreted the concept of recovery differently than researchers and professionals. The ACT service users highlighted three important elements: flexible treatment, medication and access to a car. They emphasized the necessity for basic needs to be met in order to experience a meaningful recovery process, and these basic needs may be of even greater importance to those under CTOs. Their experiences should imply a greater emphasis on securing basic needs such as secure housing, sounder finances and access to the normal benefits offered by society.     

Underdiagnosis of chronic obstructive pulmonary disease in Northern Sweden.

OBJECTIVE: To assess underdiagnosis of chronic obstructive pulmonary disease. MATERIAL AND METHODS: Two cross-sectional studies of respiratory symptoms and diseases in two population samples of the same age living in the same areas in northern Sweden were performed 6 years apart. In 1986, 5698 (86%) out of 6610 subjects aged 35-36, 50-51 and 65-66 years responded to a postal questionnaire. In 1992 an identical study was performed, and 5617 subjects (87%) out of 6434 responded. Lung function measurements were performed in stratified samples. RESULTS: Of the subjects diagnosed with chronic bronchitis only 25% in 1986 and 23% in 1992 had been diagnosed prior to the study as having chronic bronchitis, emphysema or chronic obstructive pulmonary disease (COPD). Chronic airflow limitation (CAL), used as a surrogate variable for COPD and defined as FEV1/VC <70% and FEV1 <80% of predicted value, was found in 171 subjects in 1986-1987 (12% of the examined subjects), and 166 subjects in 1993-1994 (11%). In 1986-1987, 26% of the subjects with CAL had been diagnosed as having chronic bronchitis or emphysema prior to the survey, while a diagnosis of either asthma, chronic bronchitis or emphysema, or use of asthma medicines, was found in 58%. The corresponding figures in 1993-1994 were 31% and 63%, respectively. The great majority of the subjects with CAL had recurrent wheeze, dyspnoea and chronic productive cough. CONCLUSION: Approximately 60% of the subjects with chronic airflow limitation had been diagnosed prior to the survey as having asthma, chronic bronchitis or emphysema, or were using asthma medicines. The results were similar in 1986-1987 and 1993-1994.     

Clinical pharmacology of pyridostigmine and neostigmine in patients with myasthenia gravis.

Determination of plasma concentration of pyridostigmine in 20 myasthenic patients on maintenance therapy revealed rather small intraindividual variations within a dose interval. The predose concentration varied considerably between different patients and up to seven fold in patients on the same daily dose. No pharmacokinetic interaction between pyridostigmine and neostigmine was found in five patients studied. In six patients the decrement in the deltoid muscle was studied in parallel with determination of the plasma concentrations following administration of pyridostigmine or neostigmine. In these patients the existence of a "bell-shaped" dose response curve is suggested with the maximal effect at a concentration of 30-60 ng/ml for pyridostigmine and 5-15 ng/ml for neostigmine.     

Distribution of the common tick, Ixodes ricinus (Acari: Ixodidae), in different vegetation types in southern Sweden

The aim of this study was to investigate whether differences in Ixodes ricinus (L.) nymphal relative density exist among different vegetation types in southern Sweden. Nymphal I. ricinus were sampled in southeastern Scania in southern Sweden during June-August 1997. A total of 110-180 25-m2 samples were taken by blanket-dragging from each of nine different vegetation types. There was a highly significant difference in nymphal abundance between the open areas as one group and the forested areas as another group (P < 0.0001). Vegetation types that differed significantly in median nymphal abundance from all other vegetation types were pine forest (16 nymphs/100 m2) and beech forest (40 nymphs/100 m2). No significant differences in median nymphal density were revealed among mixed deciduous forest, alder forest, oak forest, and hazel forest (28-32 nymphs/100 m2), or among dry meadow, meadow, and heath (0 nymphs/100 m2). Forestation of open areas is likely to lead to increased I. ricinus abundance and disease risk.     

The biodiversity of beneficial microbe-host mutualism: the case of rhizobia

Symbiotic nitrogen fixation is the main route for sustainable input of nitrogen into ecosystems. Nitrogen fixation in agriculture can be improved by inoculation of legume crops with suitable rhizobia. Knowledge of the biodiversity of rhizobia and of local populations is important for the design of successful inoculation strategies. Soybeans are major nitrogen-fixing crops in many parts of the world. Bradyrhizobial inoculants for soybean are very diverse, yet classification and characterization of strains have long been difficult. Recent genetic characterization methods permit more reliable identification and will improve our knowledge of local populations. Forage legumes form another group of agronomically important legumes. Research and extension policies valorizing rhizobial germplasm diversity and preservation, farmer training for proper inoculant use and legal enforcement of commercial inoculant quality have proved a successful approach to promoting the use of forage legumes while enhancing biological N₂ fixation. It is worth noting that taxonomically important strains may not necessarily be important reference strains for other uses such as legume inoculation and genomics due to specialization of the different fields. This article points out both current knowledge and gaps remaining to be filled for further interaction and improvement of a rhizobial commons.     

Adaptations of gait and muscle activation in chronic ACL deficiency

The purpose was to investigate whether deviations in gait parameters or muscular activity patterns can be detected in the injured and healthy leg of chronic ACL-deficient subjects. Sixteen medium-level active chronic ACL-deficient patients classified as “copers” (injury duration: 12–240 months, age 17–52 years) and 15 healthy subjects (age 20–33 years) walked at self-selected speed along a 10-m runway with a level force-plate. Gait specific data, ground reaction forces, knee and ankle angles, and EMG were documented. Knee laxity was increased and the functional scores (Lysholm, KOOS) decreased in the ACL- deficient subjects, whereas the Tegner activity level score was normal. Gait speed, stride length and stance time did not differ between ACL-deficient subjects and controls. Ground reaction forces (magnitude and times), as well as knee and ankle angles at selected points during stance and swing phases were normal in the ACL-deficient subjects compared to controls. The total duration of m. tibialis anterior (TA) activity was longer in ACL-deficient subjects than in controls (ACL-deficient injured leg vs. controls, P < 0.05). In addition, the onset of lateral gastrocnemius (LG) muscle activity occurred earlier in ACL-deficient patients (P < 0.03), resulting in a TA-LG cocontraction in the ACL-deficient but not in the control group. In conclusion, chronic, medium-level active ACL-deficient patients showed abnormalities in muscular activity patterns during gait compared to control subjects, whereas there were no detectable changes in ground reaction forces and 3D kinematic data. As the aberrant muscular activity pattern may be of importance for an even gait, it is proposed that EMG recordings may give additional information in the evaluation and rehabilitation of gait when the ACL is absent.     

Paired pulse facilitation of corticogeniculate EPSCs in the dorsal lateral geniculate nucleus of the rat investigated in vitro

To investigate paired pulse facilitation of corticogeniculate EPSCs, whole-cell patch-clamp recordings were made from principal cells in the rat dorsal lateral geniculate nucleus (dLGN) in vitro . Thalamic slices, oriented so that both corticogeniculate and retinogeniculate axons could be stimulated, were cut from young (16- to 37-day-old) DA-HAN rats. Corticogeniculate EPSCs displayed pronounced paired pulse facilitation at stimulus intervals up to 400 ms. The facilitation had a fast and a slow component of decay with time constants of 12 ± 7 and 164 ± 47 ms (means ± s.d .), respectively. Maximum paired pulse ratio (EPSC₂× EPSC₁⁻¹) was 3.7 ± 1.1 at the 20-30 ms interval. Similar to other systems, the facilitation was presynaptic. Retinogeniculate EPSCs recorded in the same dLGN cells displayed paired pulse depression at intervals up to at least 700 ms. The two types of EPSCs differed in their calcium response curves. At normal [Ca²⁺]_o, the corticogeniculate synapse functioned over the early rising part of a Hill function, while the retinogeniculate synapse operated over the middle and upper parts of the curve. The paired pulse ratio of corticogeniculate EPSCs was maximal at physiological [Ca²⁺]_o. The facilitation is proposed to have an important role in the function of the corticogeniculate circuit as a neuronal amplifier.     

Infant botulism acquired from household dust presenting as sudden infant death syndrome

Clostridium botulinum type B was detected by multiplex PCR in the intestinal contents of a suddenly deceased 11-week-old infant and in vacuum cleaner dust from the patient's household. C. botulinum was also isolated from the deceased infant's intestinal contents and from the household dust. The genetic similarity of the two isolates was demonstrated by pulsed-field gel electrophoresis and randomly amplified polymorphic DNA analysis, thereby confirming that dust may act as a vehicle for infant botulism that results in sudden death.