M. Anwar Iqbal

OBJECTIVE: To test the hypothesis: Time to ambulation (walking) after hip fracture surgery impacts the frequency of postoperative complications and length of hospital stay. METHODS: A retrospective observational study of a cohort of all patients admitted to a university teaching hospital with a principal International Classification of Diseases-9 diagnosis of a hip fracture during 3 calendar years. RESULTS: A total of 131 participants were identified (68% were aged 65 years or older). Overall, the mean time to writing an order to ambulate a patient after a hip fracture surgery was 2 +/- 1.5 days. Time to ambulation after hip fracture surgery was significantly less in patients cared for on orthopedic surgery service compared to general surgery service (1.8 +/- 1 vs 2.5 +/- 2, p <.05) or general internal medicine service (2.5 +/- 1.5, p <.05). It did not relate, however, to patient's age, sex, or race, or to patient's functional status prior to admission, fracture site (femoral neck, intertrochanteric, or subtrochanteric), whether a femoral neck fracture is displaced or not, type of anesthesia (spinal/epidural vs general), type of surgery (open reduction and internal fixation vs hemiarthroplasty), degree of preoperative risk, number of medical conditions, or to obtaining physical therapy and/or medical consultation. Time to ambulation after surgery was an independent predictor for the development of pneumonia (1.5 OR [odds ratio]/day, p <.001), new onset delirium (1.7 OR/day, p <.001), and to prolonged length of hospital stay (B [slope coefficient] = 1.36, p <.0001) but not to the development of pressure ulcers, deep venous thrombosis, or urinary tract infection. CONCLUSIONS: Delayed ambulation after hip fracture surgery is related to the development of new onset delirium and pneumonia postoperatively as well as to increased length of hospital stay. Early ambulation after hip fracture surgery should be encouraged.

In a comprehensive study, the temporal replication of tissue-specific genes and flanking sequences was compared in nine cell lines exhibiting different tissue-specific functions. Some of the rules we have determined for the replication of these tissue specific genes include the following. (i) Actively transcribed genes usually replicate during the first quarter of the S phase. (ii) Some immunoglobulin genes replicate during the first half of S phase even when no transcriptional activity is detected but appear to replicate even earlier in cell lines where they are transcribed. (iii) Nontranscribed genes can replicate during any interval of S phase. (iv) Multigene families arranged in clusters of 250 kilobases or less define a temporal compartment comprising approximately one-quarter of S phase. While these rules, and others that are discussed, apply to the tissue-specific genes studied here, all tissue-specific genes may not follow this pattern. In addition, housekeeping genes did not follow some of these rules. These results provide the first molecular evidence that the coordinate timing of replication of contiguous sequences within a multigene family is a general property of the mammalian genome. The relationship between replication very early during S phase and the transcriptional activity within a chromosomal domain is discussed.

In a comprehensive study, the temporal replication of tissue-specific genes and flanking sequences was compared in nine cell lines exhibiting different tissue-specific functions. Some of the rules we have determined for the replication of these tissue specific genes include the following. (i) Actively transcribed genes usually replicate during the first quarter of the S phase. (ii) Some immunoglobulin genes replicate during the first half of S phase even when no transcriptional activity is detected but appear to replicate even earlier in cell lines where they are transcribed. (iii) Nontranscribed genes can replicate during any interval of S phase. (iv) Multigene families arranged in clusters of 250 kilobases or less define a temporal compartment comprising approximately one-quarter of S phase. While these rules, and others that are discussed, apply to the tissue-specific genes studied here, all tissue-specific genes may not follow this pattern. In addition, housekeeping genes did not follow some of these rules. These results provide the first molecular evidence that the coordinate timing of replication of contiguous sequences within a multigene family is a general property of the mammalian genome. The relationship between replication very early during S phase and the transcriptional activity within a chromosomal domain is discussed.