------------------------------

Date: Mon, 02 Jan 95 22:33:55 MST
From: mednews@stat.com (HICNet Medical News)
To: hicnews
Subject: Structure and Hydration of DNA Essential for Gene Expression
Message-ID: <9y8Byc11w165w@stat.com>

           Structure and Hydration of DNA Essential
               for Control of Gene Expression

Research from The Weizman Institute of Science     May 1994  No 31


     Although proteins that regulate gene expression have been
intensively investigated, structural chemists still have much to
learn about the mechanisms by which these factors are targeted to
the genes they control and thereby enable cells to function.
     Scientists at the Weizmann Institute, working in
collaboration with Yale University researchers, have shown that a
novel recognition mechanism may enable DNA transcription factors
to recognize their regulatory sites. This discovery is of critical
importance because faulty gene regulation underlies a wide variety
of development and metabolic diseases, as well as malignancies.
The researchers found that flexing of the DNA control site makes
possible the snug intermeshing of the protein and DNA molecules
and that water molecules deeply seated in the double-helix groove
of the DNA stabilize the complex.
     According to Weizmann Institute Prof., Zippora Shakked (Dept.
of Structural Biology), a major participant in this study, one of
the best-studied control proteins, the trp repressor, supervises
the operation of genes in E. coli that enable the bacterium to
produce the amino acid tryptophan. When too much tryptophan is
present in the cell, the amino acid binds to the trp repressor
protein, which interacts with the DNA regulatory site, thereby
halting operation of these genes. In 1988, Prof. Paul B. Sigler
and his colleagues at Yale University were the first to determine
the structure of the trp repressor/DNA complex by high-resolution
X-ray crystallography. However, they were unable to see any of the
normally observed atom-to-atom interactions that would have
explained why the protein is attracted to and binds the DNA.
     In order to shed light on this question, Shakked joined
forces with her departmental colleagues - graduate student Gali
Guzikevich-Guerstein, Prof. Dov Rabinovich, and Dr. Felix Frolow -
and Prof. Sigler and his associate at Yale, Dr. Andrzej
Joachimiak. The collaborators carried out an X-ray study of the
DNA control segment in the absence of the repressor protein an
investigation that is usually more complicated than that involving
the protein/DNA complex, due to the difficulties of crystallizing
DNA and determining its structure. The DNA structural group at the
Weizmann Institute has had many years' experience carrying out
such X-ray studies.
     The Weizmann structural chemists obtained X-ray data for the
DNA control site in its unbound form and compared that structure
with the bound DNA in the complex. They discovered that the native
DNA is flexed by nearly 15 degrees when it binds to the protein,
and that water molecules present deep in the groove of the DNA
double helix provide the chemical "glue" that makes repressor
binding possible. They also found that prime recognition was based
on the overall structure of the protein and DNA surfaces, with
flexibility of the DNA allowing it to take on a structure which
complements that of the protein. This first analytical comparison
of bound and naked DNA fragments was vital to this study because
it is impossible to know from a bound DNA what its structure is in
the unbound state.
     Shakked is now applying her comparative approach for studying
the binding of regulatory proteins to genes present in mammalian
cells, some of which are involved in malignant processes.
     This investigation was reported in a recent issue of Nature.
It was supported by the U.S.-Israel Binational Science Foundation,
the Israel Science Foundation (Israel Academy of Sciences and
Humanities), the Helen and Milton Kimmelman Center for
Macromolecular Structure and Assembly, and the U.S. National
Institutes of Health.
     Prof. Zippora Shakked holds the Helena Rubinstein Chair of
Structural Biology; and  Prof. Dov Rabinovich, the William and Lee
Abramowitz Chair of Macromolecular  Biophysics.



------------------------------

Date: Mon, 02 Jan 95 22:34:57 MST
From: mednews@stat.com (HICNet Medical News)
To: hicnews
Subject: Dental Implants Show Promise for Adolescents
Message-ID: <y18Byc12w165w@stat.com>

          Dental Implants Show Promise for Adolescents

          From the National Institute of Dental Research
                          September 1994

     Preliminary results of an NIDR study suggest that dental
implants can improve the quality of life for adolescents.
Findings from the study were presented at this year's IADR/AADR
meeting in Seattle.
     Since the early 1980s, dental implants have been used to
treat adults who have lost their teeth to disease or have never
developed teeth. Many researchers thought that implants could
benefit adolescents, but there were concerns.  "A major
consideration about placing implants in adolescents had been that
the patient would outgrow the implant structure," said Dr. George
McCarthy, a dentist who is part of the NIDR implant team.  "We
have found that the implant is anchored in the bone so well that
it moves with the jaw during growth."
     NlDR's implant team-Dr. Albert Guckes, a prosthodontist now
at the University of North Carolina School of Dentistry, Dr.
McCarthy, and Dr. Jaime Brahim, an oral surgeon- placed 114
implants in the jaws of 26 adolescents with ectodermal dysplasias
(ED), a group of congenital diseases that can result in the
absence of teeth, hair, and sweat glands. The patients, 18 boys
and 8 girls, were an average of 15 years of age when they joined
the study.  The youngest patient was 12 and the oldest was 20.
     The dental researchers used titanium endosseous screw
implants, which can each hold one or more prosthetic teeth. Two
surgical procedures are required to place the implants.  First,
the oral surgeon cuts through the top of the gum tissue to expose
the jawbone.  Small holes are drilled into the bone, and a screw
implant is placed in each hole.  The gums are closed and allowed
to heal.  During the following three to six months, the implants
are osseointegrated.
     In the study, 93 of 100 implants evaluated so far were
successfully osseointegrated. "This is the most essential part of
the process," said Dr. McCarthy.  "If the implant isn't anchored
in the jaw, then we can't continue."
     In the second surgery, an incision is made to expose the
implants and a small post is put on top of each one.  Attaching
the prosthetic teeth to the posts is the final phase of the
implant process.
     Two months after the prosthetic teeth are placed, the
patients return for their first follow-up appointment.  All
patients are followed for five years.
     The NIDR researchers are currently placing implants in
children ages 7-11 years old.  They will follow these children
over the next few years to determine if the implants affect
craniofacial growth.



------------------------------

Date: Mon, 02 Jan 95 22:38:19 MST
From: mednews@stat.com (HICNet Medical News)
To: hicnews
Subject: New Listserv: Culture and Nursing
Message-ID: <k78Byc13w165w@stat.com>

Dear Colleague,

You are invited to join CULTURE-AND-NURSING, a new list sponsered by 
the
School of Nursing at the University of California - San Francisco.  
This
list was created for nurses and other health care professionals 
interested
in topics relating to culture and health.  (We apologize ahead of time 
for
duplicate postings to other lists).

 We are seeking to create an on-line community which encourages the
exchange of ideas in this exciting new field.  This list will allow
participants to address areas of cultural competence, theory, 
practice,
research, and experience in an open and unmoderated forum. It will 
give
list members the chance to discuss some of the political, economic, 
and
demographic issues affecting health care today.  It will also be an
opportunity to meet others working in the field of cross cultural and
transcultural nursing.

To subscribe to CULTURE-AND-NURSING, send the following command in the
BODY of the mail message (leave the subject header blank) to:
  majordomo@itssrv1.ucsf.edu

        subscribe CULTURE-AND-NURSING

This list uses Brent Chapman's "Majordomo" mailing list manager.  
Although
similar to listserv and listproc programs, there are a few
differences.
To receive the command list, send the following command to the list
server
(at majordomo@itssrv1.ucsf.edu):

        help

If you have any questions, please send them to:

        Chuck Pitkofsky, MS, RN
        list manager
        chuckp@itsa.ucsf.edu
        phone: 415-546-7822
        FAX:   415-546-7823



------------------------------

End of HICNet Medical News Digest V08 Issue #02
***********************************************


---
Editor, HICNet Medical Newsletter
Internet: david@stat.com                 FAX: +1 (602) 451-1165
Bitnet  : ATW1H@ASUACAD


