Finger opening in an overarm throw is not triggered by proprioceptive feedback from elbow extension or wrist flexion

 Accuracy in an overarm throw requires great precision in the timing of finger opening. We tested the hypothesis that finger opening in an overarm throw is triggered by proprioceptive feedback from elbow extension or wrist flexion. The hypothesis was tested in two ways: first, by unexpectedly perturbing elbow extension or slowing wrist flexion and determining whether changes occurred in finger opening, and second, by measuring the latency from the start of these joint rotations to the start of finger opening. Subjects threw balls fast and accurately from a sitting or standing position while joint rotations were recorded with the search-coil technique. Elbow extension was unexpectedly blocked near the start of forward motion of the hand by a rope attached to the wrist that passed through a catch mechanism located behind the subject. In spite of a slowing or complete block of elbow extension, and in some cases a replacement of elbow extension by elbow flexion, finger opening always occurred and at the same latency as for normal throws. Wrist flexion was slowed in seven of eight subjects when subjects changed from throwing with a light ball (14 g, 70 mm diam.) to a heavy ball (210 g, 65 mm diam.). For the first throw with the heavy ball, this slowing was neither fully anticipated by the subject nor compensated for by the changed proprioceptive feedback associated with the slowing. Consequently, the timing of finger opening was unchanged and (to the surprise of the thrower) the ball went high. Furthermore, in unperturbed throws with tennis balls, the latency from onset of wrist flexion or elbow extension to onset of finger opening was too short for either to have triggered finger opening (across subjects means were 4 ms for wrist flexion and 21 ms for elbow extension). In additional analysis, no relation was found between the time of onset of earlier occurring rotations at the shoulder and the time of onset of finger opening. We concluded that, although a role for all proprioceptive feedback in triggering finger opening cannot be disproved by these experiments, it can be ruled out for feedback arising from elbow extension and wrist flexion, and it seems unlikely for feedback arising from events occurring very early in the throw. The more likely possibility is that finger opening in an overarm throw is triggered by a central command based on an internal model of hand trajectory. Received: 6 July 1998 / Accepted: 16 October 1998     

Magnetically sensitive light-induced reactions in cryptochrome are consistent with its proposed role as a magnetoreceptor

Among the biological phenomena that fall within the emerging field of "quantum biology" is the suggestion that magnetically sensitive chemical reactions are responsible for the magnetic compass of migratory birds. It has been proposed that transient radical pairs are formed by photo-induced electron transfer reactions in cryptochrome proteins and that their coherent spin dynamics are influenced by the geomagnetic field leading to changes in the quantum yield of the signaling state of the protein. Despite a variety of supporting evidence, it is still not clear whether cryptochromes have the properties required to respond to magnetic interactions orders of magnitude weaker than the thermal energy, k(B)T. Here we demonstrate that the kinetics and quantum yields of photo-induced flavin-tryptophan radical pairs in cryptochrome are indeed magnetically sensitive. The mechanistic origin of the magnetic field effect is clarified, its dependence on the strength of the magnetic field measured, and the rates of relevant spin-dependent, spin-independent, and spin-decoherence processes determined. We argue that cryptochrome is fit for purpose as a chemical magnetoreceptor.     

Langerhans' cell histiocytosis--a rare cause of sudden onset unilateral sensorineural hearing loss

Langerhans' cell histiocytosis is a rare disorder of unknown aetiology in which pathological Langerhans' cells accumulate and destroy local tissue. We report a 38-year-old female who presented with a sudden onset of left sensorineural hearing loss. Magnetic resonance imaging (MRI) revealed a contrast-enhancing lesion in the left mastoid and a second lesion in the hypothalamus. Following left mastoid exploration and biopsy a definitive diagnosis of Langerhans' cell histiocytosis was made and the patient was treated with external beam radiotherapy. Subsequent right femur and right mastoid involvement were successfully treated with steroids and cytotoxic chemotherapy. At one year follow-up the patient had residual left-sided sensorineural hearing loss with normal hearing in the right ear. To our knowledge, Langerhans' cell histiocytosis has not been previously reported as a cause of unilateral sudden onset sensorineural hearing loss. It should be considered in the differential diagnosis of this condition.     

Some factors associated with compliance in the treatment of alcoholism

The investigation set out to examine the extent of problemsof low compliance at an alcoholism clinic, to investigate somevariables that might differentiate referral failures and initialclinic attenders as well as categories of patients who attendfor treatment, and to generate hypotheses concerning these differencesas a means of developing a compliance-enhancement strategy. Information, including sociodemographic and personality variables,patient self-reports of drinking behaviour, self-perceptionsof their need for help and of drinking problem severity, andtherapist ratings of drinking problem severity, was gatheredon one hundred referrals to a clinic for new patients. Results showed that 46% of patients were referral failures andthat, in comparison with attenders, the former group had bothwaited longer for the initial appointment and were younger.Few variables differentiated the categories of attenders. Agreater proportion of those remaining in treatment contact forlonger than a month rated the change in their drinking problemover the previous year as ‘worse’ and more of themhad been arrested for public drunkenness. Those who made fiveor more clinic visits had waited a shorter time for their initialappointment, and a greater proportion rated the effects of theirdrinking on their work as ‘serious’ and the changein their social life as ‘worse’ than patients whohad made fewer visits. The findings suggest that variables related to personal perceptionsof drinking problems offer a better account of compliance behaviourthan the sociodemographic variables which have been the focusof previous research.     

Male transsexualism in England: Sixteen cases with surgical intervention

The syndrome of transsexualism is now regarded as a distinct entity separate from transvestism and homosexuality (Benjamin, 1966; Green and Money, 1969). It refers to those patients who since childhood have been convinced of their wrong sex assignment and who wish to attain the sexual characteristics of the opposite sex and to live as a member of that sex. The present report is an initial one referring to the first group of transsexual patients studied at a postgraduate teaching hospital by a multidisciplinary team. Their study has three aims: first, to compare this group of patients with other series; second, to evolve a surgical technique of sex reassignment; and, finally, to assess the success of such surgery in allowing the patients to attain a satisfactory adjustment in their new gender role.     

Kinematics of Arm Joint Rotations in Cerebellar and Unskilled Subjects Associated with the Inability to Throw Fast

Cerebellar subjects and unskilled throwers cannot produce fast arm movements when throwing. We investigated the arm movement kinematics associated with this lack of skill. Cerebellar subjects and matched controls, and skilled throwers throwing with their skilled (dominant) and unskilled (nondominant) arms, were instructed to make slow, medium, and fast 3-D overarm throws from a sitting position. Only the fast throws were analyzed in detail. Joint motions were computed from angular positions of arm segments recorded with search coils. When throwing, both the cerebellar group and the unskilled-arm group had slower arm movements, and slower elbow extension and wrist flexion velocities than their reference groups. They also had similar magnitudes of many kinematic parameters, e.g., both cerebellar and unskilled groups had similar elbow extension and wrist flexion velocities. Compared to their reference groups, both the cerebellar and unskilled-arm groups also had a smaller elbow extension acceleration, a smaller shoulder adduction deceleration, and the absence of a large elbow extension deceleration before ball release. Similar decreases in joint velocities and in joint accelerations and decelerations in the cerebellar and unskilled groups are consistent with the idea that the absence of the skill of throwing fast in both groups is associated with an inability to exploit interaction torques.     

Audit of referrals for head and neck cancer – the effect of the 2‐week,fast track referral system

Audit of referrals for head and neck cancer – the effect of the 2‐week, fast track referral system The NHS Cancer Plan sets out targets for the diagnosis and treatment of cancer. Ideally, there should be a maximum of a 2‐week wait from a referral for suspected cancer to an outpatient appointment. A fast track referral system has been established nationally, with general practitioners given guidelines as to appropriate referrals. In the South Essex region, we audited all such referrals using this system for a 12‐month period and also all new patients diagnosed with head and neck cancer during the same period. We found that 71% of patients diagnosed with cancer were not referred using the fast track system and that only 15% of patients who were referred by the fast track system were subsequently found to have cancer. For patients with cancer who were referred using standard letters, the time from referral to initial consultation was generally much longer than the recommended period of 2 weeks. We conclude that improvements in utilizing the fast track system need to be made if it is to bring about an improvement in early diagnosis of head and neck cancer. As things stand, it may actually be detrimental for most cancer patients.     

New Record of <Emphasis Type="Italic">Equisetum ramosissimum</Emphasis> subsp. <Emphasis Type="Italic">debile</Emphasis> from Lower Gangetic Plain,West Bengal,India and Conservation Approach

A recent survey for pteridophytic flora in the lower Gangetic plain of West Bengal, India reports the natural occurrence of Equisetum ramosissimum Desf. subsp. debile (Roxb. Ex Vauch.) Hauke (Equisetaceae) from alluvial Gangetic zone of North 24 Parganas district (22°55′39.00″N and 88°26′14.94″E) which adds new record to the existing database of pteridophytic flora in the region. Regular observations show that the population of E. ramosissimum is sustained completely by vegetative means due to non-formation of reproductive organ i.e. strobilus in an individual plant in any season. The community analyses through standard ecological methods reveal heterogeneous phyto-assemblages in both winter and rainy seasons, however, seasonal variations are observed in species diversity and frequency. Simpson’s Index of Diversity in both plant communities suggests diverse species richness and evenness in the area. Importance Value Index depicts ecological dominance of E. ramosissimum in both seasons. The plant has significant positive correlation with angiospermic taxa, Mikania micrantha and Typha angustifolia in winter and rainy seasons, respectively but is negatively correlated with Xanthium indicum and Desmostachya bipinnata, correspondingly. These observations may be taken into consideration for in situ conservation of the species. Systematic conservation plan is suggested to protect this newly revealed taxon, E. ramosissimum subsp. debile which demands regular awareness program among local people for continued future sustainability as the area is regularly invaded by human footsteps. Finally, the present investigation may motivate the young workers for field study to explore the nature in better way.