Spontaneous resolution of diffuse alveolar septal amyloidosis

Amyloidosis is a generic term for a heterogeneous group of disorders associated with deposition of protein in an abnormal fibrillar form. Amyloidosis can be hereditary or acquired, localised or systemic and potentially lethal or merely an incidental finding. We report a case of a male who was totally asymptomatic and was incidentally detected to have lung amyloidosis. He was not given any treatment but kept under observation., His chest radiograph (CXR) and high resolution computed tomograph (HRCT) of the chest cleared spontaneously after one year and the patient continues to remain asymptomatic even after two years.

A successful strategy for preimplantation genetic diagnosis of myotonic dystrophy using multiplex fluorescent PCR

The most common form of inherited muscular dystrophy in adults is myotonic dystrophy (DM), an autosomal-dominant disease caused by the expansion of an unstable CTG repeat sequence in the 3' untranslated region of the myotonin protein kinase (DMPK) gene. Expanded (mutant) CTG repeat sequences are refractory to conventional PCR, but alleles with a number of repeats within the normal range can be readily amplified and detected. Preimplantation genetic diagnosis (PGD) of DM has been successfully applied. However, a misdiagnosis using the reported protocol was recently documented. Two new PGD protocols for DM have been developed which utilise multiplex fluorescent PCR. Ideally a linked polymorphic marker, APOC2, is amplified in addition to the normal DMPK alleles, thus providing a back-up diagnostic result. However, the two couples reported in the present study were not fully informative at the APOC2 locus and so an unlinked short tandem repeat (STR) marker, D21S1414, was substituted. The highly polymorphic nature of the D21S1414, DMPK and APOC2 loci means that a very simple genetic fingerprint can be generated by analyses of these loci. This allows most DNA contaminants to be detected. Contamination is a significant problem for PGD and is the primary reason for the inclusion of D21S1414 and APOC2 in this protocol. This paper reports the first clinical experience and pregnancies following PGD for DM using a multiplex fluorescent PCR protocol.

Prader-Willi syndrome with sleep disordered breathing: effect of two years nocturnal CPAP

We report a case of a 3-year-old child with Prader-Willi syndrome who had severe sleep disordered breathing with daytime hypersomnolence. His daytime blood gases showed type II respiratory failure. He was effectively treated with continuous positive airway pressure (CPAP) and has used this form of therapy for 2 years now with improvement in daytime somnolence, improved mental acuity and normalisation of daytime blood gases.

Crystal structures of c-Src reveal features of its autoinhibitory mechanism

Src family kinases are maintained in an assembled, inactive conformation by intramolecular interactions of their SH2 and SH3 domains. Full catalytic activity requires release of these restraints as well as phosphorylation of Tyr-416 in the activation loop. In previous structures of inactive Src kinases, Tyr-416 and flanking residues are disordered. We report here four additional c-Src structures in which this segment adopts an ordered but inhibitory conformation. The ordered activation loop forms an alpha helix that stabilizes the inactive conformation of the kinase domain, blocks the peptide substrate-binding site, and prevents Tyr-416 phosphorylation. Disassembly of the regulatory domains, induced by SH2 or SH3 ligands, or by dephosphorylation of Tyr-527, could lead to exposure and phosphorylation of Tyr-416.

Control of tubercular haemoptysis by bronchial artery embolization

Thirty-seven patients presenting with massive or recurrent haemoptysis secondary to tuberculous aetiology were subjected to bronchial artery angiography. Of these, failure, to catheterize the bleeding vessel occurred in two patients while embolization was withheld in two patients due to the presence of anterior spinal artery arising from a common intercosto-bronchial trunk. Immediate arrest of bleeding was performed in the remaining 33 patients by selective embolization of the abnormal bronchial arteries with a resorbable material (Gelfoam). Regular follow up for a duration of 6 months after the procedure revealed relapse of haemoptysis in four patients; three were treated by re-embolization of the abnormal bleeding vessels while one patient died due to aspiration immediately on admission. No recurrence of bleeding was seen in the remaining 29 patients. It is concluded that bronchial artery embolization is an effective treatment for immediate control of life-threatening haemoptysis.

Loosening and osteolysis of cemented joint arthroplasties. A biologic spectrum

The purpose of this study was to characterize the cell types (using immunohistochemistry) and cytokine expression (using in situ hybridization) of tissues surrounding well fixed and loose cemented prostheses undergoing revision. Clinical and radiographic data were gathered prospectively for a series of cemented total joint replacements undergoing revision. Three groups were identified: (1) loose implants with osteolysis (10 specimens), (2) loose implants without osteolysis (11 specimens), and (3) well fixed implants (7 specimens). At surgery, a specimen was harvested from the bone cement interface. Immunohistochemical staining was performed using monoclonal antibodies to identify macrophages and lymphocyte subgroups. Human antisense probes were selected to identify the mRNA for specific cytokines using in situ hybridization. The percentage of positively staining cells was determined for each antibody or probe using a grid counting technique. Tissues from loose cemented prostheses with osteolysis contained significantly greater numbers of macrophages and T lymphocytes compared with tissues from loose and well fixed cemented prostheses without osteolysis. The number of interleukin-1 and interleukin-6 positive cells was highest in specimens with osteolysis and lowest in specimens from well fixed prostheses. These cytokines modulate the growth and differentiation of cells in the immune system and the monocyte and macrophage system and mediate the remodeling of bone and mesenchymal tissues. Specific cell populations and cytokine profiles appear to be involved in periprosthetic osteolysis; this information may be useful in planning strategies for prevention and treatment.

Effects of particulate high-density polyethylene and titanium alloy on tissue ingrowth into bone harvest chamber in rabbits

The purpose of this study was to determine whether small, phagocytosable particles of titanium alloy (Ti) and high-density polyethylene (HDPE) have an adverse effect on bone ingrowth. The bone harvest chamber (BHC) was implanted bilaterally in the proximal tibial metaphysis of six mature rabbits. The BHC has a transverse 1-mm wide pore providing a continuous canal through the chamber for tissue ingrowth. After an initial 6-week period for osseointegration of the BHC, the contents of the canal were harvested repeatedly at 3 weekly intervals. This could be done with the chamber in place, without disturbing its exterior surface or the surrounding bone. The carrier solution, 1% sodium hyaluronate (Healon) was implanted first. In subsequent implantations, Healon was mixed with particles of HDPE or Ti averaging 4.7 +/- 2.1 and 3.0 +/- 2.6 microns, respectively. The contralateral chamber was left empty and served as a control. The chambers were harvested repeatedly, alternating experimental and control sides. The sections from the control side, and those containing Healon alone demonstrated extensive trabecular bone in a fibrovascular stroma. The sections containing Ti alloy particles were qualitatively and quantitatively similar to the control sections and those containing Healon, except for the presence of small black granules of Ti alloy, dispersed in the fibrovascular stroma or phagocytosed by scattered macrophages. The sections containing HDPE particles were infiltrated and engulfed by mononuclear and multinuclear histiocytic cells in a highly fibrous stroma. The majority of the multinucleated cells present were interpreted as being foreign body giant cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Cessation of strain facilitates bone formation in the micromotion chamber implanted in the rabbit tibia

Short, daily periods of externally-applied strain have been shown previously to affect the differentiation of mesenchymal tissue. In this study, we examine the effects of discontinuing a strain protocol known to produce primarily fibrous tissue rather than bone in the micromotion chamber (MC). Five MCs were inserted into the proximal tibial metaphysis of mature male New Zealand white rabbits. The MC has a 1 x 1 x 5 mm pore for tissue ingrowth. After osseointegration of the fixed outer cylinder of the chamber, the inner movable core was manipulated for 40 cycles per day delivered at a rate of 1 Hertz ('40'). This provided motion at the interface between the cylinder and the core. The tissue in the pore was harvested after 3 wks. The MCs were then manipulated at 40 cycles per day for 3 wks and then the manipulations were discontinued for 3 additional wks ('40 + 0'); the contents of the chamber were harvested after 6 wks. Finally, the chambers were left without manipulation ('0') and harvested after 3 wks. Histological sections from unmoved chambers ('0') contained extensive trabecular bone, embedded in a fibrovascular stroma. The '40' specimens were composed primarily of longitudinally orientated fibrous tissue. The '40 + 0' specimens were similar histologically to the '0' specimens. The amount of bone ingrowth expressed as a percentage of the area of the section averaged 37 +/- 6 (mean +/- standard error of the mean) for the '0' specimens, 20 +/- 2 for the '40' specimens and 37 +/- 7 for the '40 + 0' specimens.(ABSTRACT TRUNCATED AT 250 WORDS)

Cement particles inhibit bone growth into titanium chambers implanted in the rabbit

Particles of bone cement have been shown previously to stimulate the resorption of bone. The purpose of this study was to determine whether particles of bone cement (BC) have an adverse effect on bone ingrowth. The bone harvest chamber was implanted bilaterally in the proximal tibial metaphysis of 6 mature rabbits. Both the fixed outer cylinder and the inner removable core of the chamber have a transverse 1 mm wide pore providing a continuous canal for tissue ingrowth. After an initial 6-week period for osseointegration of the outer cylinder, the contents of the inner core were harvested repeatedly at 3 weekly intervals. In the first series of rabbits, the carrier solution, 1% sodium hyaluronate (Healon) was implanted first. In subsequent implantations, Healon was mixed with small fabricated particles of BC (averaging 3.54 mm in diameter) to fill the channel of the core. The contralateral chamber was left empty and served as a control. In the second series of rabbits, implantation was carried out sequentially using the same material bilaterally. The sections from the control harvests, and those with Healon alone contained extensive trabecular bone arranged longitudinally in the canal, in a fibrovascular stroma. The sections containing BC particles were infiltrated by foamy, mononuclear and multinuclear histiocytic cells. Less trabecular bone was seen in the sections containing BC particles compared to the control sections or those containing Healon alone. Previous studies have shown that particles of bone cement stimulate bone resorption. In this study, BC particles have also been shown to diminish the formation of new bone.

Difference in bone ingrowth after one versus two daily episodes of micromotion: experiments with titanium chambers in rabbits

Mechanical stimulation has been shown to affect the differentiation and development of mesenchymal tissue. In the present study, we compared the histological and histomorphometric results of tissue ingrowth into micromotion chambers that were moved at 0 cycles per day, 20 cycles once per day, and 20 cycles twice per day over 20-30 sec, for 3 weeks. In each case, a chamber having a 1 x 1 x 5 mm square-holed groove for tissue ingrowth was used. The total amplitude of motion was 0.75 mm. Histological sections from nonmoved chambers contained extensive trabecular bone, embedded in a fibrovascular stroma. Histomorphometric analysis disclosed that bone comprised a mean of 31 +/- 2% (mean +/- SEM) of the ingrown tissue. Twenty movements per day appeared to further stimulate bone ingrowth (46 +/- 5%). Extensive ingrowth of more immature woven and trabecular bone was noted in a more cellular stroma. In general, increasing the degree of micromotion to 20 movements twice per day resulted in a decreased amount of bone formation (19 +/- 7%). In several of these specimens, little or no bone could be found. These experiments have demonstrated that, for the parameters chosen in this study, a short daily period of low frequency, micromotion may facilitate bone ingrowth; however, when the same motion is delivered twice daily, bone ingrowth is depressed. Thus a "window" of externally applied strain appears to exist, which may facilitate or discourage tissue differentiation to bone.