Streptozotocin or streptozocin (INN, USP) (STZ) is a naturally occurring alkylating antineoplastic agent that is particularly toxic to the insulin-producing beta cells of the pancreas in mammals. It is used in medicine for treating certain cancers of the islets of Langerhans and used in medical research to produce an animal model for hyperglycemia and Alzheimers in a large dose, as well as type 2 diabetes or type 1 diabetes with multiple low doses. Usage
Streptozotocin is approved by the U.S. Food and Drug Administration (FDA) for treating metastatic cancer of the pancreatic islet cells. Since it carries a substantial risk of toxicity and rarely cures the cancer, its use is generally limited to patients whose cancer cannot be removed by surgery. In these patients, streptozotocin can reduce the tumor size and reduce symptoms (especially hypoglycemia due to excessive insulin secretion by insulinomas). A typical dose is 500 mg/m2/day by intravenous injection, for 5 days, repeated every 4–6 weeks. Due to its high toxicity to beta cells, in scientific research, streptozotocin has also been long used for inducing insulitis and diabetes on experimental animals. Streptozotocin has also been used for modeling Alzheimers disease through memory loss in mice. Mechanism
Streptozotocin is a glucosamine-nitrosourea compound. As with other alkylating agents in the nitrosourea class, it is toxic to cells by causing damage to the DNA, though other mechanisms may also contribute. DNA damage induces activation of PARP which is likely more important for diabetes induction than the DNA damage itself.
Delta-beta thalassemia is a rare form of thalassemia in which there is a reduced production of hemoglobin subunit delta and hemoglobin subunit beta and raised levels of hemoglobin subunit gamma. It is an autosomal recessive disorder. Signs and symptoms
An individual with delta-beta thalassemia is usually asymptomatic, however  microcytosis can occur where the  red blood cells are abnormally small. Mechanism
Delta-beta thalassemia is autosomal recessive disorder, which means both parents are affected and two copies of the gene must be present. A carrier gets a normal gene to produce hemoglobin A, from one parent and the other parent supplies a gene which makes no hemoglobin A. Delta-beta thalassemia is considered rare.Delta-beta-thalassemia is caused by deletions of the entire delta and beta genes sequences and only gamma-globin and HbF are formed. Rarely, non-deletional forms have been reported.When two delta0 mutations are inherited, no hemoglobin A2 (alpha2, delta2) are formed. This is innocuous because only 2-3% of normal adult hemoglobin is hemoglobin A2. The individual will have normal hematological parameters (erythrocyte count, total hemoglobin, mean corpuscular volume). The delta-beta thalassemia demonstrates one mutation is at the +69 position. Relation to beta thalassemia
Delta-beta thalassemia can mask the diagnosis of beta thalassemia trait. In beta thalassemia, an increase in hemoglobin A2 results, but the co-existence of a delta-beta thalassemia mutation will decrease the value of the hemoglobin A2 into the normal range, thereby obscuring the diagnosis of beta thalassemia trait

Diagnosis
Following the detection of hypochromic microcytic red blood cells, delta-beta thalassemia is confirmed by high-performance liquid chromatography.