Reliability of an intravenous intermittent access port (saline lock) for obtaining blood samples for coagulation studies.

BACKGROUND: Patients admitted to rule out myocardial infarction often receive a heparin infusion that requires measurement of partial thromboplastin time every 6 to 8 hours until coagulation values stabilize. If the patient's acuity at admission does not necessitate placement of arterial or central catheters, insertion of an intermittent intravenous access port (saline lock) would decrease the need for frequent venipuncture. Many studies on obtaining blood samples via arterial and central catheters have been reported, but no reports have described the method of using a saline lock or the amount of blood discarded during that procedure. OBJECTIVE: To evaluate the efficacy of inserting a saline lock specifically for obtaining blood samples and to determine the amount of blood that must be discarded in order to obtain prothrombin and partial thromboplastin times that match the values from blood samples obtained via venipuncture. METHODS: Coagulation values determined with 2 consecutive blood samples obtained via the saline lock after the first 0.5 mL of blood withdrawn was discarded were compared with measurements determined with a blood sample obtained via venipuncture. RESULTS: Prothrombin and partial thromboplastin times were not significantly different among the 3 blood samples. CONCLUSION: The untoward effects of frequent venipunctures to obtain blood samples for measurement of prothrombin and partial thromboplastin times can be lessened by using an 18-gauge saline lock to obtain blood samples and discarding the first 0.5 mL of blood withdrawn before the samples for coagulation studies are collected.

Sex determination in dioecious Silene latifolia. Effects of the Y chromosome and the parasitic smut fungus (Ustilago violacea) on gene expression during flower development.

We have embarked on a molecular cloning approach to the investigation of sex determination in Silene latifolia Poiret, a dioecious plant species with morphologically distinguishable sex chromosomes. One of our key objectives was to define a range of genes that are up-regulated in male plants in response to Y chromosome sex-determination genes. Here we present the characterization of eight male-specific cDNA sequences and classify these according to their expression dynamics to provide a range of molecular markers for dioecious male flower development. Genetically female S. latifolia plants undergo a partial sex reversal in response to infection by the parasitic smut fungus Ustilago violacea. This phenomenon has been exploited in these studies; male-specific cDNAs have been further categorized as inducible or noninducible in female plants by smut fungus infection. Analysis of the organ-specific expression of male-specific probes in male and female flowers has also identified a gene that is regulated in a sex-specific manner in nonreproductive floral tissues common to both male and female plants. This observation provides, to our knowledge, the first molecular marker for dominant effect of the Y chromosome in nonreproductive floral organs.

Spatial expression dynamics of Men-9 delineate the third floral whorl in male and female flowers of dioecious Silene latifolia.

Sex determination in Silene latifolia is controlled by heteromorphic sex chromosomes. Female flowers have five fused carpels and ten arrested stamen primordia. The male-determining Y chromosome overrides female development to suppress carpel formation and promote stamen development. The isolation and characterization of two S. latifolia. Male enhanced cDNAs, Men-9a and Men-9b, which probably represent different alleles of a novel gene are reported here. Men-9a and Men-9b share 91.8% coding sequence nucleotide identity, yet only 85.4% amino acid identity. The Men-9 cDNAs are related to the previously reported MROS3 cDNA from S. latifolia. However, MROS3 is not present in the S. latifolia population used in these studies and the expression dynamics of Men-9a and Men-9b contrast dramatically with those reported for MROS3. Men-9 cDNAs are expressed primarily in anthers of young male flowers, with highest expression in 1-2 mm buds. Men-9 expression is also observed at a low level in female flowers. In situ hybridization analysis reveals two phases of Men-9 expression. The first phase is during a common stage of early stamen development in male and female flowers prior to stamen arrest in female flowers. The second phase of Men-9 expression is maximal in the epidermis and endothecium of Y chromosome- and Ustilago violacea-induced stamens; expression in male and female flowers extends to the epidermis of the staminal nectaries with strict boundaries at the second and fourth whorls, Men-9 gene expression therefore delineates the boundaries of the third floral whorl in S. latifolia flowers.