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                    D e n t a l    F o l l i c l e               

             The        Monthly     E-newsletter                   Vol - I V    Number-  I I         July 2009

In this Issue:

  • Editorial

  • News

  • DentistryUnited @ Rank 7 on GOOGLE

  • Laughter - The best Medicine

  • HEMOGLOBINOPATHIES A Review- Part 2

  • Indonesians Win Dental Research Competition

  • Study IDs Saliva MicroRNA Differences in Those with Oral Cancer                                             

  • Science Proves The Danger Of Bleeding Gums- Milwaukee Journal September/6/ 1921

     

 

Editorial :

      Dear Fellow Dentist,

                               Integrating the "General Dentist's" studies with a university or research center should be a primary goal of the times. The general dentist  who normally  "sees and does" maximum of the cases in many a times in his own "originally-researched" ways on the particular "Ethinic patients" , could result as a major investigator thereby decreasing the time 

                              As we look for more ideas and support for this ideology from our esteemed readers, we bring you this edition of Dental Follicle.

                             I hope you enjoy this issue.

                                           

Click here to join DentistryUnited
Click to join DentistryUnited

Yours truly

Dr. Syed  Nabeel

Editor of Dental Follicle & WebMaster www.DentistryUnited.com

News :

         

                        DentistryUnited Ranks 6 on Google  for key word "Dentistry"

Laughter - The Best Medicine :

Adam And Eve had many advantages. The princial one was that they escaped teething.




 

                                         

 

 

HEMOGLOBINOPATHIES   A Review - Part II

By Dr.Ghazala Danish MDS

Oral Diagnostitian & Radiologist

 

Prevention

Genetic councelling in cases where parents have sickle cell triat. There are obvious economic implications especially as the disease is more prevalent in the areas of the world where money for high technology is limited.

 

Management

Gene replacement therapy

Bone marrow transplantation

 

General management for alleviation of symptoms

Regular foilc acid supplements 5mg/day to support increased erythopoietic activity.

Prevention and prompt treatment of infections.

Patient should avoid becoming chilled, dehydrated or exposed to hypoxia like at high altitudes.

Patient should be adequately hydrated.

Transfusion should be done when Hb level falls below 5gm%.

Acute pain crisis- powerful potentially addictive analgesics may be necessary. After 24-48 hrs they should be replaced with milder, non-addictive analgesics. Exchange transfusion may be required to alleviate bouts of severe intractable pain.

Immunization with pneumococcal vaccine.

Ulcers- rest, elevation, dry dressings with antimicrobials. Healing takes weeks to months.

Patient support groups to be made for patient's psychiatric support.

 

Newer therapies

Hydroxyurea- it inhibits ribonucleotide reductase blocking DNA synthesis and cell division. The drug also enhances fetal hemoglobin by the developing erythrocytes (HbF blocks sickling).

 

Experimental therapies

Erythropoietin- a hormone produced by the kidneys that stimulates red cell production. This hormone is produced in response to hypoxemia. It increases fetal hemoglobin in RBCs.

Butyrate (Arginine butyrate)- babies born to diabetic mothers with poor glucose control sustain production of HbF after birth relative to babies born to normal women. Butyrate is a byproduct of hyperglycemia.

Clotrimazole (anti-fungal / anti-mycotic belonging to imidazole group)- red cell dehydration contributes to polymerization of sickle Hb in patients with sickle cell anemia. Clotrimazole inhibits dehydration, thus is being tried.

Nitric oxide- it is an inhaled gas. It primarily relaxes the smooth muscles. However it also forms a covalent link with Hb affecting polymerization.

 

Prognosis

In Africa a few shildren with sickle cell anemia survive to adult life without medical attention. With standard medical care 15% will die by the age of 20yrs and 50% by the age of 40yrs.

 

Thalassemia

Thalassemia is an inherited impairment of hemoglobin production, where there is partial or complete failure to synthesize a specific type of globin. This causes formation of abnormal hemoglobin thus causing anemia. It is quantitative disorder of hemoglobin.

It is autosomal recessive blood disease.

Epidemiology

Thalassemia is prevalent among Mediterranean people. Thalassa in Greek means sea, Haema in Greek means blood, hence the name thalassemia.

It is prevalent in populations living in humid climates. Malaria is endemic in these areas. Thalassemia protected these people from malaria as the blood cells in these patients are degraded easily.

Classification

Based on which globin chain of hemoglobin is affected thalassemia can be classified as follows:

1.       Alpha thalassemia- production of alpha globin chain is affected.

2.       Beta thalassemia- production of beta globin chain is affected.

3.       Delta thalassemia- production of delta globin chain is affected.

Alpha thalassemia

There is decrease in the alpha globin production due to concerned gene deletion, resulting in excess of beta globin chains in adults and excess gamma chains in new borns. The excess beta globin chains form unstable tetramers (Hb called HbH). They involve HBA1 and HBA2 genes inherited in a Mendelian recessive fashion.

When all genes are deleted it can present as hydrops fetalis. Hydrops fetalis is a condition in the fetus characterized by accumulation of fluid or edema in at least two fetal compartments, including the subcutaneous tissue, pleura, pericardium or in the abdomen. Edema is usually seen in the fetal subcutaneous tissues sometimes leading to spontaneous abortion. It is a prenatal form of heart failure, in which heart is unable to satisfy its demand for a high amount of blood flow. It is usually due to fetal anemia when the heart needs to pump a much greater volume of blood to deliver the same amount of oxygen.

Beta thalassemia

It is due to mutations in the HBB gene inherited in a Mendelian recessive fashion. There is no formation or reduced formation of beta chains depending upon the type of mutations. Relatively there is excess formation of alpha globin chains. They donot form tetramers, but bind to the cell membrane damaging it.

 

Delta thalassemia

3% adult hemoglobin has two alpha and two delta chains. Just as with beta chains, mutations can occur in genes responsible for delta chain production.

 

Thalassemia can co-exist with other hemoglobinopathies

Hemoglobin E / Thalassemia

Hemoglobin S / Thalassemia

Hemoglobin C / Thalassemia

 

Beta thalassemia is of two types:

Thalassemia minor- has one affected beta thalassemia gene and one normal beta chain gene.

Thalassemia major- has both affected beta thalassemia genes.

 

Thalassemia minor

An individual with thalassemia minor has only one affected beta thalassemia gene (together with one perfectly normal beta chain gene). The person is said to be heterozygous for beta thalassemia.

Affected individuals have mild anemia resembling iron deficiency anemia with little or no clinical disability. They have normal blood iron levels. Usually detected when iron therapy for mild microcytic anemia fails. No treatment is usually required.

 

Thalassemia major (Cooley's anemia)

The clinical picture associated with thalassemia major was first described in 1925 by the American pediatrician Thomas Cooley, hence the name Cooley's anemia.

An individual with thalassemia major has two affected beta thalassemia genes and no normal beta chain gene. The individual is said to be homozygous for beta thalassemia. This is a serious condition as there is a striking deficiency in beta chain production of HbA.

At birth an infant with thalassemia major appears normal. This is because of predominant fetal hemoglobin (HbF). It has two alpha and two gamma chains. Since HbF has no beta chains, the infant does not manifest the affects of thalassemia major. As the HbF levels start decling anemia begins to develop from the first months after birth. Anemia progressively increases in severity. Infant fails to grow normally, has feeding problems due to easy fatigue from lack of oxygen. There are bouts of fever due to infections predisposed by anemia. Dairrhoea and other intestinal problems are also encountered.

Splenmomegaly is common is thalassemia due to high rate of hemolysis. Spleen identifies the RBCs in thalassemia as defective and removes them from circulation. In case of transfused red cells the spleen identifies them as invaders foreign to the body and removes them also from the circulation. Therefore transfused red blood cells survive only for a few weeks, whereas normal RBCs have a life span of about 120 days.hyperactivity and increase in the number of cells filtered in the spleen leads to splenomegaly.

Iron toxicity- Iron deposits due to chronic blood transfusion exceed the storage capacity of ferritin (iron storage protein of the body). Consequently free / loosely bound iron begins to accumulate in tissues and blood. Theis free iron catalyses the formation of hydroxyl radicals (OH) from hydrogen peroxide which are normal metabolic byproducts. Hydroxyl radicals are highly reactive. They attack lipids, proteins and DNA to form peroxides (Eg: lipid peroxide). The peroxides interact with other molecules to form cross links. These cross linked molecules perform their normal function poorly or not at all. DNA cross links impair cell replication, leading to cell death.

Liver- hepatocytes are the major storage site for body iron. With iron overload, these cells are affected and eventually die. They are replaced by fibroblasts causing liver fibrosis and cirrhosis. Similarly cardiac cells are damaged by iron overload. Damaged, poorly functioning cells often fail. Clinical manifestations include congestive heart failure (due to injury to myocytes) and arrhythmias (due to damage to the cells of the cardiac conducting system).

 

 

Orofacial manifestations

Enlargement of maxilla due to eryhtroid mass leading to chipmunk facies. Spacing of teeth, forward drift of maxillary incisors. Therefore orthodontic treatment is indicated.

Expansion of diploe of skull giving rise to hair on end appearance conspicuous on lateral skull radiographs.

Alveolar bone rarefaction produces chicken wire appearance.

Pneumatization of the sinuses is delayed.

Painful swelling of the parotid glands and xerostomia caused by iron deposition.

Sore or burning tongue due to folate deficiency, as most of the folic acid is utilized by increased erythropoiesis.

 

Dental considerations

There is increased risk of hepatitis B or C, HIV carriage due to repeated blood transfusions.

If splenectomy has been done, it results in immune defects. Prophylactic antibiotics have to be administered pre-operatively.

Local anesthesia can be safely given.

General anesthesia is difficult / contraindicated because of chronic anemia and cardiomyopathy. Even intubation becomes difficult because of enlarged maxilla.

 

Carrier detection / prevention

There is a serious concern that thalassemia may become a very serious problem in the next 50 yrs, burdening world's blood bank supplies and the health care system in general.

In autosomal recessive forms of the disease, both parents must be carriers for the child to be affected. If both parents carry a hemoglobinopathy triat there is 25% chance with each pregnancy for the child to be affected.

Therefore Genetic counseling and genetic testing is recommended for families that carry a thalassemia triat.

Premarital screening policy exists in Cyprus and Iran to reduce the incidence of thalassemia.

 

Diagnosis

·         Geographic location of the individual

·         Family history

·         Complete blood count- Hemoglobin level in blood is reduced. Moderate and severe thalassemias are usually diagnosed in early childhood (severe anemia appears within 2 yrs of life). Milder forms of thalassemia are diagnosed after a routine blood test showing anemia. There is microcytosis, hypochromia.

·         Hemoglobin electrophoresis-mild form of thalassemia shows higher than normal amounts of HbA2 and HbF. Severe form of thalassemia shows low levels of HbA and high levels of HbF.

·         Ferritin blood test (to check iron level in blood)- normal in thalassemia minor and raised in thalassemia major.

 

Treatment

Thalassemia minor usually does not require any specific treatment.

Talassemia major

·         Chronic blood transfusion to maintain hemoglobin level more than 10gm%.

·         Iron chelation therapy- to prevent iron mediated injury to the cells, thus preventing heart, liver damage caused by iron overload. When metal ion binds to the chelator, the metal ion becomes chemically inert. Therefore chelator detoxifies metal ions and prevents poisoning. Iron chelator desferrioxamine removes excess iron that accumulates with chronic blood transfusion. It is not absorbed from thegastrointestinal tract. It has to be given as continuous subcutaneous infusion or continuous intravenous infusion. It involves expensive medical paraphernalia. Given 5-7 days a week.

·         Splenectomy

·         Allogenic hematopoietic transplantation

·         Administration of folic acid 5mg daily.

·         Anti-oxidant indicaxanthine prevents oxidation of RBCs and prevents hemoglobin degradation.

·         Recent reports suggest that 3% of patients with beta thalassemia produce HbF. Use of hydroxyurea increases the production of HbF.

General management for alleviation of symptoms

Prevention and prompt treatment of infections.

Patient support groups / psychiatric support

 

Indonesians Win Dental Research Competition

The University of Indonesia claimed first prize in a scientific research competition held by the Asia Pacific Dental Students Association in Penang, Malaysia, last week, beating several prominent universities, including some from South Korea and Malaysia.

Devie Rahmawati, the deputy director of corporate communications at UI, said their team competed against 14 other teams from other dental hygiene faculties across the region, including Malaysia, South Korea and Cambodia. A team from Greece, from the European Association of Dental Students, also participated.

Devie said that the university won with innovative research titled: “The Effect of Xylitol on Candida Albicans Growth and Its Resistance in Serum (In Vitro Study).”

Malaysia came second and South Korea third.

 

 

VIDEO OF THE MONTH

 

 

 

 

 

 

 

 

Study IDs Saliva MicroRNA Differences in Those with Oral Cancer

 A team of  researchers from California and Serbia, used reverse transcriptase pre-amplification quantitative PCR to identify nearly 50 miRNAs in saliva samples from a dozen healthy individuals.Later they assessed a subset of these in individuals with   oral squamous cell carcinoma, the team found four miRNAs that were differentially expressed, including two that were at significantly lower levels in oral cancer patients.The study would be published in Clinicl cancer research September Issue.

Harvard's New Dental School -

 

Milwaukee Journal September/6/ 1921

Science Proves The Danger Of Bleeding Gums