Stereo electron microscope studies of mitotic chromosomes from Chinese hamster ovary cells.

Stereo electron microscopy was employed to examine thin sections of Chinese hamster ovary metaphase chromosomes in situ and of chromosomes released from Chinese hamster ovary cells by several methods. Detergent lysis of cells in a buffer containing Mg++ and Ca++ and hypotonic lysis of cells in a hexylene glycol-Ca++ buffer released chromosomes that exhibited a three-dimensional meshwork of about 50 nm chromatin fibers. Fragmentation of cells in serum-free medium by vortexing with glass beads revealed a more dispersed chromosomal morphology with a mesh of 10 to 25-nm fibers exhibiting a presumptive nucleosomal substructure. Possible origins of the various fiber sizes are discussed in terms of current models of metaphase chromosome structure.

Is postural instability exacerbated by off-loading devices in high risk diabetics with foot ulcers?

Pressure reduction is of pivotal importance in any treatment plan designed to heal diabetic foot ulcers. However, to our knowledge, no work has evaluated the effect of ambulatory pressure reducing devices on postural stability (PS) in high risk diabetics. Therefore, the purpose of this study was to compare PS associated with 5 off-loading strategies: total contact casts with cast boot, total contact casts with heel, removable cast walker, half-shoes, and canvas shoes using a repeat measure design. Twenty-six diabetic patients with foot ulcers were enrolled in the study. Using a digital pressure platform, the degree of sway was measured as total deviation of center of force. Three 30 second trials were evaluated using Turkey's studentized range test for multiple comparisons (alpha = 0.05). Sway was significantly greater with total contact casts with heel compared to other devices. While total contact casting remains the gold standard with which to treat neuropathic ulcers, care should be taken when placing patients in any devices that may exacerbate postural instability. The results suggest that total contact casts with an incorporated rubber heel may indeed accentuate sway. It is therefore recommended that the rubber heel be eliminated in lieu of a protective cast boot when using this modality.

Triple arthrodesis and subtalar joint arthrodesis. For the treatment of end-stage posterior tibial tendon dysfunction.

The current literature clearly supports the use of subtalar and triple arthrodeses for the treatment of end-stage PTTD. There is debate, however, regarding whether or not an isolated fusion is preferable to the triple arthrodesis. Complete evaluation of the patient's deformity and symptoms is imperative before choosing to perform a rearfoot fusion. If the deformity can be isolated to the STJ, then perhaps a limited fusion is appropriate. With the close interrelationship of the subtalar and midtarsal joints, however, it is the authors' opinion that chronic dysfunction of the posterior tibial tendon infrequently causes isolated STJ pathology. Perhaps earlier intervention in the process of tendon degeneration, before multiple joint adaptations, would warrant an isolated fusion. We anticipate further research into the advantages of STJ and double arthrodeses over the triple arthrodesis. Clearer identification of the patients in whom these limited fusions are warranted is necessary, especially with respect to adult flatfoot secondary to PTTD. Currently, isolated and combined hindfoot fusions continue to be valuable salvage procedures in the treatment of end-stage arthritic deformities.

Treatment of posterior tibial tendon dysfunction with tendon procedures from the posterior muscle group.

The use of tendons from the posterior muscle group, specifically the FDL, as a means to repair PTTD is useful for the early stages of the deformity. Once the patient has reached the later stages and the foot becomes rigidly deformed with loss of the medial longitudinal arch, however, any attempt to reconstruct the area with tendon work alone fails. Tendon repair, tenodesis, and tendon transfer are attractive treatment options for PTTD, but care should be taken in choosing the correct patient for these procedures. Some authors note that side-to-side tenodesis does not address arch realignment. Other procedures combined with tendon work perhaps can help to reduce the shortcomings of isolated tendon procedures. Subtalar joint arthroeresis in combination with the tendon work seems to solve this problem. The authors have begun to explore this option and have performed this procedure on some patients. It is premature to address the effectiveness of this combined procedure. Similarly, tendon procedures augmented with other soft-tissue-type procedures also remains an option and is mostly ignored in the medical literature. Deland et al experimented with reconstruction of the spring ligament in a cadaver study, and believed that it should be considered in any reconstructive flatfoot surgery. Likewise, Myerson used some capsular reefing of the talonavicular joint in his tendon reconstruction to aid the correction of the forefoot-to-rearfoot relationship. The treatment of the patient with PTTD remains driven by the surgeon's preference, with little scientific research to guide him or her. There is much controversy regarding the efficacy of tendon procedures and the specific surgical technique of each procedure. Some variations may prove inconsequential, whereas others may prove revolutionary. The authors believe that the use of the tendon work as a means of treatment for PTTD is viable alone or in combination with other procedures. Much research is still needed to identify the best technique for each stage of the deformity. Wiekland has attempted to do this, but unfortunately has not offered any long-term follow-up to justify his treatment algorithms. Foot and ankle specialists should strive for clinical research, which allows better understanding of the appropriate treatment options for each progressive stage of PTTD.

Complications of distal first metatarsal osteotomies.

Many surgical procedures have been described for the correction of hallux valgus and hallux limitus deformities. Distal first metatarsal osteotomies have been advocated since the turn of the century, and have been modified and improved since that time. Various complications have been associated with distal osteotomies, but there is infrequent reference to the normal changes in joint function, foot biomechanics, and forefoot pressures after surgery. The following literature review addresses the postoperative effects of decreased first metatarsophalangeal joint motion, shortening of the first metatarsal, dorsal displacement of the capital fragment, and transfer metatarsalgia on foot function.

Initiation of DNA replication in chromosomes of Chinese hamster ovary cells.

The initiation of DNA replication and the subsequent chain elongation were studied using Chinese hamster ovary cells synchronized at the beginning of S phase. The cells were synchronized by a combination of mitotic selection and treatment with 5-fluorodeoxyuridine (FdU). The use of this drug at a concentration of 10(-5) M was found to effectively prevent the leakage of cells into S phase. Reversal of the FdU block by supplying thymidine resulted in the synchronous onset of initiation at multiple sites in each cell. The length of the nascent chains, as determined by autoradiography and velocity sedimentation in alkaline gradients, increased linearly with time during the first twenty minutes of S phase after release. We applied these procedures to study the effects of the length of an FdU block on the number of functional origins per cell, the rate of chain growth, and the rate of DNA synthesis per cell following reversal of the block. Although no change was noted in the rate of DNA synthesis in cells held at the beginning of S phase from 10.5 to 24 h after division, the rate of chain growth decreased from 0.94 to 0.28 microns per min. This decrease indicated that the number of functional origins increased markedly with length of FdU block. The calculated number of utilized origins per cell increased from 1,900 to 5,700. We also presented arguments that 1,900 origins per cell represents the approximate number of origins utilized by any cell held at the beginning of S phase for less than 10.5 h after division.

Lower extremity manifestations of Vibrio vulnificus infection.

Vibrio vulnificus is a potentially lethal marine bacterium that has not been previously described in podiatric literature. A review of the microorganism's characteristics, susceptible patient population, and lower extremity manifestations of infection is presented. V. vulnificus is found as part of the normal flora of the Gulf of Mexico, Atlantic, and Pacific coastal waters and is often isolated from the filter feeding shellfish of these regions. Its pathogenicity is generally reserved for the immunocompromised host, and is specifically related to disease states which exhibit high serum iron levels. V. vulnificus infections present in two distinct clinical syndromes: primary sepsis secondary to raw oyster ingestion, or localized infection from wound exposure to V. vulnificus-inhabited salt water. Both syndromes demonstrate characteristic skin lesions of the trunk and extremities that present as hemorrhagic bullae and progress to necrotic ulcerations. Although V. vulnificus infection is rare, its extreme virulence in patients suffering from a chronic disease process and its manifestation of characteristic lower-extremity lesions require the podiatric physician to be able to recognize and treat such a condition.

Electrical stimulation in wound healing.

The authors present a review of the current literature regarding electrical stimulation with special focus on the merits of its uses in wound healing. Literature from a basic science, animal studies and clinical investigations are reviewed. The literature seems to suggest that electrical stimulation can effect wound healing, but the method of delivery remains uncertain.

Fractionation of the gene-size macronuclear chromatin fragments of the binucleated eukaryote Oxytricha.

The macronuclear chromatin of Oxytrichia nova consists of chromatin fragments which are fully soluble in 0.2 mM EDTA and whose DNA length varies from 500-25 000 bp. The DNA migrates electrophoretically as a series of discrete bands, with specific genes present in only one or a few bands. The chromatin fragments are composed of nucleosomes and migrate electrophoretically in proportion to their DNA length. These results suggest schemes for the fractionation of undigested chromatin in order to enrich for specific genes, facilitating analysis of changes in chromatin structure associated with changes in gene expression.

Soft tissue and bone infections from puncture wounds in children.

We report on the prevalence of osteomyelitis, the prevalence of soft tissue infections, and the type and number of pathogens encountered in bone and soft tissue infections caused by puncture wounds in children. In addition, we seek to establish whether shoe gear plays a role in the flora in infected puncture wounds and if laboratory indices are indicative of the presence of infection. The group consisted of 44 nondiabetic children admitted to hospital for puncture wounds of the foot. Cultures were positive for osteomyelitis in 7 patients (16%), all involving the forefoot (P < .04). The most common pathogen in soft tissue infections was Staphylococcus aureus. The most common pathogen in osteomyelitis was Pseudomonas aeruginosa. There was no significant difference in the prevalence of osteomyelitis and soft tissue infection based on footwear. There were no cases of osteomyelitis encountered among barefoot children (P < .04). In 10 cases (83%), P aeruginosa infection (both soft tissue and bone) occurred while the patients were wearing tennis shoes (P < .04). In this study, the leukocyte count (normal in 29 patients [66%]), erythrocyte sedimentation rate (normal in 28 patients [64%]), and temperature (normal in 44 patients [95%]) did not have any predictive value in differentiating soft tissue infection from osteomyelitis in children.

The natural history of great toe amputations.

The purpose of this study is to report the prevalence of reamputation following resection of the great toe and first ray in adults with diabetes. We abstracted the medical records of 90 diabetic great-toe and first-ray amputees admitted between 1981 and 1991. The most common etiologies of initial amputations were ulcer with soft tissue infection (39%), ulcer with osteomyelitis (32%), and puncture wounds (12%). Sixty percent of all patients had a second amputation, 21% had a third, and 7% had a fourth. Fifteen percent of the patients who had a second amputation had it contralaterally. Seventeen percent subsequently underwent a below-knee amputation and 11% had a Transmetatarsal amputation on the same extremity, 3% had a below-knee amputation, and 2% a transmetatarsal amputation contralaterally. The mean time from the first to the second amputation was approximately 10 months. The results of this study suggest that a large proportion of patients undergoing an amputation at the level of the great toe or first ray have subsequent amputations in the first year following the initial procedure. Additionally, it appears that the contralateral foot may be at significant risk for distal amputation following resection of the hallux or first day.

The effects of diabetes mellitus on the material properties of human metatarsal bones.

While some investigations have focused on the effect of diabetes on the material properties of connective tissue in both the human and animal model, no study to date has investigated the effects of the disease process on human metatarsal bones. This investigation compared the material properties of human metatarsal bones from young diabetic donors (51.3 +/- 8 years) and older nondiabetic donors (72.3 +/- 10 years). The results demonstrated no significant differences between the two groups. This would seem to suggest that the effects of aging are comparable to the effects of diabetes on the structural integrity of human metatarsal bones.

Physical structure of gene-sized chromatin from the protozoan Oxytricha.

Oxytricha nova is a hypotrichous ciliate containing a transcriptionally active macronucleus and a transcriptionally inactive micronucleus. Two-dimensional gel electrophoresis shows that macronuclei contain a normal complement of inner histones. However, despite extensive efforts, no classical H1-like protein has been detected. Micrococcal nuclease digestion indicates a nucleosome repeat length of approximately 220 bp for macronuclear chromatin. Thermal denaturation profiles of macronuclear chromatin in 0.2 mM EDTA display four transitions at about 46, 57, 64, and 79 degrees C. The lowest of these shifts to higher temperature as the ionic strength is raised to 3-5 mM Na phosphate. These results are consistent with the absence of H1 and a nucleosome repeat of 220-230 bp. Circular dichroism (CD) results agree with these findings. By contrast, micronuclear chromatin displays a much smaller premelt and a more suppressed DNA CD signal at 285 nm, consistent with a micronuclear chromatin repeat of 165-185 bp as determined by micrococcal nuclease digestion.

Effects of diabetes mellitus on the biomechanical properties of human ankle cartilage.

Metabolic changes attributable to diabetes mellitus affect numerous organ systems in the body. For example, patients with diabetes have an increased number of musculoskeletal injuries and afflictions compared with patients without diabetes and experience more morbidity associated with injury and treatment. Although diabetes also may afflict articular cartilage, no studies have shown a conclusive link between diabetes and cartilage structural integrity. The objective of this study was to obtain and compare the intrinsic material properties of human ankle articular cartilage from patients with diabetes and those without diabetes. These biomechanical properties (aggregate modulus, Poisson's ratio, shear modulus, and permeability) were found to differ significantly between specimens from patients with diabetes and patients without diabetes. Specifically, cartilage from patients with diabetes was significantly softer and more permeable than cartilage from control subjects. For example, in the central portion of the talus, cartilage from patients with diabetes had a 38% smaller aggregate modulus, 37% smaller shear modulus, and 111% larger permeability than did tissue from patients without diabetes. These results provide evidence that joint pathologic processes in patients with diabetes may be associated with compromised structural integrity of articular cartilage.

Rehabilitation of eosinophilic fasciitis. A case report.

Eosinophilic fasciitis (EF), first described in 1974, is characterized by the sudden onset of painful swelling with induration of the soft tissues and peripheral eosinophilia, often after an episode of intense physical exertion. It rapidly progresses to joint contractures because of inflammation and fibrosis of the fascia. Of the 200 cases reported in the medical literature, most have responded positively to a prolonged course of oral prednisone. Although complete recovery is possible, more frequently signs and symptoms of EF persist. There were no detailed descriptions found in the literature of any rehabilitative interventions in this disease. This case study describes the methods used in a successful, comprehensive rehabilitation treatment of a 21-yr-old man admitted to the Palo Alto VA Medical Center rehabilitation program 8 mo after the onset of symptoms. Previous medication therapy included prednisone and methotrexate. The patient underwent 2 mo of inpatient rehabilitation, which consisted of upper and lower extremity nerve blocks, serial splinting, application of physical modalities, massage, stretching and strengthening exercises and interdisciplinary pain management. Significant improvement was made in the range of motion in all extremities, strength, hand function, level of pain, gait and endurance. Aggressive therapy did not increase eosinophilia. In fact the eosinophil count returned to normal by the time of discharge. A detailed review of the patient's rehabilitation program is presented.