Modified rare earth semiconductor oxide as a new nucleotide probe.

Recent rapid developments in biological analysis, medical diagnosis, pharmaceutical industry, and environmental control fuel the urgent need for recognition of particular DNA sequences from samples. Currently, DNA detection techniques use radiochemical, enzymatic, fluorescent, or electrochemiluminescent methods; however, these techniques require costly labeled DNA and highly skilled and cumbersome procedure, which prohibit any in-situ monitoring. Here, we report that hybridization of surface-immobilized single-stranded oligonucleotide on praseodymium oxide (evaluated as a biosensor surface for the first time) with complimentary strands in solution provokes a significant shift of electrical impedance curve. This shift is attributed to a change in electrical characteristics through modification of surface charge of the underlying modified praseodymium oxide upon hybridization with the complementary oligonucelotide strand. On the other hand, using a noncomplementary single strand in solution does not create an equivalent change in the impedance value. This result clearly suggests that a new and simple electrochemical technique based on the change in electrical properties of the modified praseodymium oxide semiconductor surface upon recognition and transduction of a biological event without using labeled species is revealed.

Volunteer case aides in the U.S.A.

Mrs. Jeanne Lewington was awarded a 1973 Winston Churchill Fellowship to visit the U.S.A. and look at the way volunteers are used, particularly in the field of mental health. She studied projects at State and Private Mental Hospitals and Community Health Centres. She was particularly impressed with the contribution of Volunteer Case Aides in one to one work with psychiatric patients and describes this principle in some detail. On her return Mrs. Lewington approached the King's Fund London and has been given a grant to finance the establishment of a two year Volunteer Case Aide Programme based at St. Crispin Hospital, Northampton, England, evaluation of which will take place during 1975.

A first Volunteer Case Aid programme in a mental hospital. Revealing the voluntary helper's role of reality testing between staff and patients.

A pilot Voluntary Case Aid programme in an English Mental Hospital using National Health Service resources is described. The selection of ten volunteers and ten patients and the preparation of all personnel was followed by regular contacts for at least a year. Subsequent evaluation suggested high motivation with both Case Aids and patients. Changes towards improved social functioning were evident in most cases by the end of the project. A relationship starting, continuing and finishing is reported in detail and from this study it is clear that the volunteer was a reality tester for staff and patient alike, constructively disturbing and modifying their mutual projections. This was true of most of the Case Aid interventions and the implications are discussed. A method of group supervision for Case Aids is reported.

Environmentally directed mutations in the dehalogenase system of Pseudomonas putida strain PP3.

Favourable mutations involving the two dehalogenases (DehI and DehII) of Pseudomonas putida PP3 and derivative strains containing the cloned gene for DehI (dehI) occurred in response to specific environmental conditions, namely: starvation conditions; the presence of dehalogenase substrates (halogenated alkanoic acids--HAAs) which were toxic to P. putida; and/or the presence of a potential growth substrate. Fluctuation tests showed that these mutations were environmentally directed by the presence of HAAs. The mutations were associated with complex DNA rearrangements involving the movement of dehI located on a transposon DEH. Some mutations resulted in switching off the expression of either one or both of the dehalogenases, events which were effective in protecting P. putida from toxic compounds in its growth environment. Other mutations partially restored P. putida's dehalogenating capability under conditions where toxic substrates were absent. Restoration of the capability to untilize HAAs was favoured when normal growth substrates were present in the environment.